RU2829485C2 - Pull-out unit - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to electric power distribution centers and motor control centers, in particular to pull-out units, which can be completely removed from the assembly of low-voltage distribution equipment and control equipment without switching off the assembly. For this purpose, the pull-out unit for the compartment of the functional unit of the unit of low-voltage distribution equipment or control equipment has a locking mechanism controlled by a push button in the test and connected positions, isolated lockable mechanism for maintenance and release mechanism to prevent falling of pull-out unit from compartment of functional unit of specified unit. To prevent accidental insertion of the pull-out unit into an improper compartment of the functional unit, an insertion lock is provided. Pull-out unit contains gaskets, which improves the degree of protection (IP code) when the pull-out unit is in a fully connected position.

EFFECT: providing protection of electrical components installed on the rear side of the pull-out unit against accidental insertion of the pull-out unit into an improper compartment of the functional unit.

57 cl, 24 dwg

Description

AREA OF TECHNOLOGY

The present invention relates to the field of power distribution centres and motor control centres, in particular to withdrawable units that can be completely removed from a low-voltage switchgear and control equipment unit without switching off the unit.

LEVEL OF TECHNOLOGY

Low-voltage switchgear and controlgear units are designed to distribute electric power to consumers. The units are divided internally into sections, subsections and compartments depending on the end user's requirements. In a low-voltage switchgear and controlgear unit, in accordance with international standards IEC 61439, there may be three types of compartments: functional unit compartments, busbar compartments and cable compartments. Terminals for external conductors are located in cable compartments. The functional units of a low-voltage switchgear and controlgear unit are located in functional unit compartments. A functional unit is a drawer-like part of a low-voltage switchgear and controlgear unit containing electrical and mechanical elements, including switching devices, conductors connecting the functional unit to the main or distribution buses and to terminals for external conductors, which are part of the functional unit. The functional units of the low-voltage switchgear and controlgear assembly may be of four different types, i.e. fixed, plug-in, removable and withdrawable. Each of these units differs from the other in the convenience and practicality of inserting and extracting the unit from the low-voltage switchgear and controlgear assembly without completely disconnecting the low-voltage switchgear and controlgear assembly. The withdrawable unit is a functional unit designed to move from the connected position to the isolated position and to the test position, while remaining in the functional unit compartment of the low-voltage switchgear and controlgear assembly. When inserting the withdrawable unit into its functional unit compartment, the fork plugs installed inside the withdrawable unit are connected to the corresponding socket plugs installed inside the functional unit compartment. The withdrawable units contain electrical and mechanical devices that are used to connect and disconnect the main circuits and auxiliary circuits. Most withdrawable units have three positions - the connected position, the test position and the isolated position. In the connected position, the withdrawable unit is fully connected to the main circuits as well as the auxiliary circuits. In the test position, the main circuit is open but not necessarily isolated, and the auxiliary circuits are connected to perform the test operations while the withdrawable unit is still inside the functional unit compartment. In the isolated position, both the main circuits and the auxiliary circuits are open while the withdrawable unit is still inside the functional unit compartment.

Low voltage switchgear and controlgear manufacturers produce withdrawable units with various functions such as locking mechanisms, position indicators, etc. One of the important problems in the modern low voltage switchgear and controlgear assembly industry is to produce easy-to-operate, compact low voltage switchgear and controlgear units. Therefore, producing a compact withdrawable unit without compromising any of its essential basic functions and safety requirements in accordance with international standards has become one of the major challenges for manufacturers. In an attempt to design a compact withdrawable unit, manufacturers have developed various technologies in the locking and unlocking mechanism in the connected, test and isolated positions.

The present invention is a compact drawer unit equipped with a plurality of locking mechanisms in accordance with international standards. The drawer unit disclosed in the present invention application uses a push-and-hold locking device that locks the drawer unit in the test position and the connected position and is released by a push button. In addition, the invention uses an isolated locking mechanism and a final release mechanism of the unit to improve the safety of operators.

The closest analogue to the invention is disclosed in EP 2625757 - Locking device for withdrawable units of electrical switchgear cabinets - which describes another type of locking mechanism controlled by a push button. Although this invention uses a push button to control the locking mechanism, the technology used here differs from the technology used in the invention. The locking mechanism in this analogue uses a locking device, the locking element of which moves when the push button is pressed in different locking positions.

A second analog, closer to the invention, is disclosed in patent No. KR 101178740 B1 - A modular type engine control center having an extension position indicating a push-button type device for extension of its block - where its locking control mechanism locks the block using rails installed to prevent relative movement or to release the locking. This analog has a position control mechanism for visually indicating the position of the block.

A third analogue, closer to the invention, is disclosed in patent No. WO/2002/087037 - Low-voltage switchgear containing a locking device for an instrument module - where another locking mechanism is used to lock the device in different positions. The locking mechanism contains a locking plate located in the housing of the block, positioning cranks located on the side edges of the lower part of the block, and a lifting device.

TECHNICAL PROBLEM

When it comes to withdrawable units used in low-voltage switchgear and controlgear assemblies, the size of the withdrawable unit is one of the important factors in the industry. Low-voltage switchgear and controlgear manufacturers are constantly engaged in R&D work on the design of compact withdrawable units to minimize the size of the low-voltage switchgear and controlgear assemblies. End users require compact functional units with high working current to save space.

Reducing the size of the withdrawable unit is a technical challenge, as compactness must be achieved while complying with IEC 61439 standards. On the one hand, a compact withdrawable unit must not weaken the safety requirements that the common low-voltage switchgear and controlgear assembly is expected to provide for its operators. The safety of personnel working in the vicinity of low-voltage switchgear and controlgear assemblies is one of the most serious requirements in the industry.

On the other hand, the mechanical actions of the drawer unit, such as the locking mechanisms, need to be isolated from the main purpose of the drawer unit, which is to connect and disconnect the internal circuits with the incoming and outgoing circuits without shutting down the entire unit. Since the space inside the drawer unit is limited, there must be enough space inside the drawer unit to install the electrical components that are used to control and distribute electricity.

DISCLOSURE OF THE ESSENCE OF THE INVENTION

The invention is a drawer-type sliding unit, which is used in a low-voltage electrical switchgear and control unit. The drawer unit is improved by a plurality of locking mechanisms. Its push-and-hold locking device automatically locks the drawer unit in different positions in its functional unit compartment and unlocks the drawer unit by pressing a push button. It is also equipped with two more locking mechanisms, i.e. an isolated locking mechanism and a final release mechanism of the unit. The drawer unit comprises an insertion blocker to prevent accidental insertion of the drawer unit into an inappropriate functional unit compartment. The drawer unit has a position sensor means to receive an indication of the drawer unit position.

BENEFICIAL EFFECTS

In addition to the push-and-hold locking mechanism, the drawer unit contains two additional locking mechanisms, i.e., an isolated locking mechanism and a final release mechanism for the unit. The isolated locking mechanism can be engaged or disengaged depending on the operator's requirements. Operators can safely lock the drawer unit using a padlock when carrying out repair or maintenance work. The drawer unit can be equipped with a position sensor device to detect the position of the drawer unit when it is inserted or removed. The drawer unit has a special bracket for mounting the position sensor device. The insertion lock protects the electrical components mounted on the rear side of the drawer unit from accidentally inserting the drawer unit into an incorrect compartment of the functional unit. The drawer unit has been improved in terms of protection rating (IP code) when it is in the fully connected position.

BRIEF DESCRIPTION OF DRAWINGS

The drawings are not drawn to scale. Some components of the invention are illustrated as being comparatively larger or smaller in size than their actual appearance.

Fig. 1 illustrates a first embodiment of the invention, i.e. a sliding block and rails.

Fig. 1A illustrates the external appearance of a first embodiment of the invention.

Fig. 2 and 2A illustrate the internal view of the sliding block.

In Fig. 3, 3A, 3B and 3C, a push-and-hold locking device is illustrated. In Fig. 3B and 3C, the bracket (25b) is not shown in order to illustrate the release pin (22) and the guide sleeve (22b).

Fig. 4 illustrates the top rail and the bottom rail.

Fig. 4A is a further illustration of the top rail.

Fig. 4B illustrates the release plate (84) and the longitudinal edge (83) of the upper rail.

Fig. 4C is a further illustration of the bottom rail.

Fig. 5 illustrates the drawer unit (1) when it is completely removed from the functional unit compartment.

Fig. 6 and 6A illustrate the locking device (70).

In Fig. 7, 7A, 7B and 7C an isolated locking mechanism (30) is illustrated.

Fig. 8 and 8A illustrate the release mechanism (50) of the block.

Fig. 9 and 9A illustrate the insertion lock (110).

Fig. 10 illustrates a second embodiment (120) of the invention, i.e. a sliding block (120) with two pressing and holding locking devices.

DETAILED DESCRIPTION OF EXAMPLES OF IMPLEMENTING THE INVENTION

The invention is a withdrawable unit used in low-voltage switchgear and control equipment units, inside which electrical devices are installed for distributing electrical energy and protecting equipment and users from electric shock. The withdrawable unit is located in a compartment of a functional unit in a low-voltage switchgear and control equipment unit. Plug devices are installed inside the withdrawable unit and in a compartment of the functional unit to create the necessary withdrawable connections and disconnections. When the withdrawable unit is inserted into its compartment in a low-voltage switchgear and control device unit, the fork plug devices are mechanically connected to the corresponding socket plug devices, allowing the power and control connections coming from the internal switching devices installed in the withdrawable unit to be connected to external cables connected to the outgoing circuit. When the withdrawable unit is removed from its compartment in the low-voltage switchgear and control equipment assembly, the fork-type plug devices are mechanically disconnected from the corresponding socket-type plug devices, and the power connections are disconnected from the external cables. The withdrawable unit has locking positions, namely connected, test, isolated lockable and block release, at different places along the entry and exit path when it is inserted and removed from the functional unit compartment. The invention is equipped with a "press and hold" locking mechanism implemented using a multifunctional device controlled by a push button for locking and unlocking the withdrawable unit in different locking positions, as well as for ensuring proper electrical connections and disconnections. The invention discloses two versions of such withdrawable units, in which the difference between the two withdrawable units lies in the number of press and hold locking devices used to unlock the unit in different positions.

Fig. 1 shows a first embodiment of the invention, which is a relatively small drawer unit (1) having a structure similar to a drawer and a set of rails (80 and 81) made of sheet metal. For ease of description, the three sides of the drawer unit (1) are designated as the front side (2), the right side (3) and the rear side (4) of the drawer unit (1); the direction of movement, i.e. forward and backward, is indicated in the following description with respect to the functional unit compartment. Forward movement means movement of the drawer unit or its component in the direction of the front side of the functional unit compartment. Backward movement means movement of the drawer unit or its component toward the rear side of the functional unit compartment.

As further shown in Fig. 1A, the drawer unit (1) on the outside comprises a control handle (10), a gasket (11), a push button (12) and a front door (13) on its front side (2). The drawer unit (1) comprises a locking pin (21), a release pin (22), an isolated locking mechanism (30), an on/off mechanism (40), a release mechanism (50) of the unit, a bracket (100) of the position sensor and a locking device (110) of insertion.

As shown in Fig. 2, a mounting plate (60) for mounting electrical devices is fixed inside the drawer unit (1). Cutouts (61) for plugs are made in the rear side (4) of the drawer unit (1). A cuff gasket (62) is provided, fixed to the rear part of the door holding plate (63) of the drawer unit (1). The gasket (11), shown in Fig. 1, seals the end of the control handle (10). The two gaskets (11 and 62) prevent water and dust from entering the drawer unit (1) when the drawer unit (1) is completely inserted into the compartment of the functional unit. In this way, the protection degree (IP code) of the drawer unit (1) is increased. Locking and unlocking of the drawer unit (1) in the connected and test positions is ensured by means of a push-and-hold locking device (20), fixed inside, on the right side wall (3) of the drawer unit (1). The isolated locking mechanism (30) and the release mechanism (50) of the block are attached to the lower part (5) of the sliding block (1). As shown in Fig. 2B, the locking device (70) is also attached inside, on the right side wall (3) of the sliding block (1).

As shown in Fig. 3, the pressing and holding locking device (20) comprises a push button (12), a locking pin (21), a release pin (22) and a movable plate (23). The locking pin (21) is attached from the inside to a bracket (25a), which is attached to the inner right side wall (3) of the sliding unit (1). The release pin (22) is attached from the inside to a bracket (25b), which is attached to the inner upper wall of the sliding unit (1). The cover (24) of the mechanism covers the actions of the locking pin (21) and the release pin (22). The push button (12), the locking pin (21) and the release pin (22) are loaded by springs (26a, 26b and 26c), respectively. The force of the spring (26a) is greater than the force of the spring (26b) or the spring (26c).

As shown in Fig. 3A and Fig. 3B, the movable plate (23) is a metal plate attached internally to the right side wall (3) of the drawer unit (1) using screws (27a), spacers (27b) and a pressed-in post (27c), which allows the movable plate (23) to move freely back and forth through the guide grooves (23a and 23b). Near the end of the movable plate (23), where the push button (12) is fixed, there is a beveled bend (23c) with a beveled guide groove (23d). Closer to the other end, the movable plate (23) has a rectangular bend (23e) with a trigger element (23f), which is used to control the locking device (70), that is, to move the locking device (70) up and down, which is described in paragraph 3 on page 13. The movable plate (23) has a keyhole-type groove (23g), located between the beveled guide groove (23) and the first guide groove (23a). The guide grooves (23a and 23b), the beveled guide groove (23d) and the keyhole-type groove (23g) are located at three different levels on the movable plate (23). The guide grooves (23a and 23b) are located at the same level. The keyhole type groove (23g) has two sections, namely Section A (23h), which is rounded, and Section B (23i), which is rectangular in shape with rounded edges.

As shown in Fig. 3C, the locking pin (21) has a flange (21a) and passes through the spring (26b), the bracket (25a), the guide sleeve (21b) and the cover plate (24) of the mechanism. The guide sleeve (21b) is riveted to the bracket (25a). The spring (26b) is held between the bracket (25a) and the flange (21a) of the locking pin (21). The locking pin (21) is secured slightly spring-loaded by means of a nut (21c) for free movement inside the guide sleeve (21b). Thus, the system of the cover plate (24) of the mechanism, the separator (21b), the bracket (25a) and the spring (26b) allows the locking pin (21) to be pressed or released. The width of the beveled guide groove (23d) is slightly larger than the diameter of the head of the locking pin (21), which allows it to exit through the beveled guide groove (23d). The diameter of the flange (21a) is slightly larger than the diameter of the head of the locking pin (21), which allows it to rest on the edge of the beveled guide groove (23d).

As shown in Fig. 3, 3A, 3B and 3C, the release pin (22) has a step (22a) and passes through the spring (26c), the bracket (25b), the guide sleeve (22b) and the cover plate (24) of the mechanism. The guide sleeve (22b) is riveted to the bracket (25b). The spring (26c) is held between the bracket (25b) and the step (22a) of the release pin (22). The release pin (22) is secured and slightly spring-loaded by means of a nut (22c) for free movement inside the guide sleeve (22b). Thus, the system of the cover plate (24) of the mechanism, the separator (22b), the bracket (25b) and the spring (26c) allows the release pin (22) to be pressed or released. The head of the release pin (22) passes through the keyhole-type groove (23g) on the movable plate (23) and is additionally spring-loaded and pressed when its step (22a) hits and rests on the inner edge of Section B (23i) of the keyhole-type groove (23g). The width of Section B (23i) of the keyhole-type groove (23g) is slightly larger than the diameter of the head of the release pin (22), which allows it to exit through Section B (23i) of the keyhole-type groove (23g). The diameter of the step (22a) is slightly larger than the diameter of the head of the release pin (22), which allows it to rest on the inner edge of Section B (23i) of the keyhole-type groove (23g). The diameter of the step (22a) of the release pin (22) is slightly smaller than the diameter of Section A (23h) of the keyhole-type groove (23g), which allows the release pin (22) to exit through Section A (23h), allowing the spring (26c) to expand to its original state.

The pressing and/or releasing of the locking pin (21), the release pin (22) or/and the push button (12) is carried out in combination with the forward and backward movement of the movable plate (23), as described in the following two paragraphs 2 and 3 on page 9.

[Paragraph 2, page 9]

When the movable plate (23) moves backwards relative to the locking pin (21), it (21) is fully spring-loaded and pressed, since the reverse movement of the bevel in the beveled guide groove (23d) moves the shoulder (21a) of the locking pin (21) inward. When the movable plate (23) moves backwards relative to the release pin (22), the Section A (23h) of the keyhole-type groove (23g) moves to the location of the release pin (22). As a result, the step (22a) of the release pin (22) comes out through the Section A (23h) of the keyhole-type groove (23g), since it (22) is spring-loaded by the spring (26c), and restrains further movement of the movable plate (23). As a result, the push button (12) remains pressed, and the spring (26c) remains loaded. Thus, the release pin (22) is released when the movable plate (23) moves backward relative to the release pin (22).

[Paragraph 3, page 9]

When the release pin (22) is pressed inward in any way, the step (22a) of the release pin (22) moves inward and allows the movable plate (23) to move forward under the action of the loaded spring (26a), by means of which the push button (12) is released from its pressed state. The forward movement of the movable plate (23) brings the Section B (23i) of the keyhole-type groove (23g) to the location of the release pin (22). As a result, the step (22a) hits and rests on the inner edge of the Section B (23i) of the keyhole-type groove (23g), so that the release pin (22) is pressed. When the movable plate (23) moves forward, the beveled guide groove (23d) moves forward relative to the locking pin (21) and releases the locking pin (21).

As shown in Fig. 4, the rails, i.e. the upper rail (80) and the lower rail (81), are used to guide and position the withdrawable unit (1) in its compartment of the functional unit of the control and distribution device assembly. The front side of each rail (80 and 81) is designated by an engraved arrow (96). The inner surfaces of all rails that touch the moving withdrawable unit (1) have relief surfaces (97) to reduce friction between the withdrawable unit (1) and the rails (80 and 81) when the withdrawable unit (1) moves.

As shown in Fig. 4A, the upper rail (80) is a metal plate, two longitudinal edges (80A and 80b) of which are bent at a right angle. The longitudinal edge (80a) is the side on which the pressing and holding locking device (20) is attached to the sliding block (1). The longitudinal edge (80a) is further bent at a right angle, forming a longitudinal edge (83) with a beveled projection (83a), two rectangular recesses (83b and 83d), a rectangular projection (83c) between the two recesses (83b and 83d) and a long edge (83e). The release plate (84) is a metal plate fixed on the longitudinal edge (80a). The release plate (84) is formed by a beveled projection (84a), a beveled recess (84b), a triangular projection (84c) and a beveled projection (84d) open on one side. The longitudinal edge (80a) of the upper rail (80) has two guide bushings (85) with a riveted steel ball. The riveted steel ball in the guide bushing (85) is designed with the possibility of rotation inside the guide bushing (85). The upper rail (80) is attached to the frame elements in the functional block compartment by means of screws inserted through the fastening holes (86). The upper rail (80) has two block stoppers (87), which are used to stop the movement of the sliding block (1) into the block compartment in the event of a malfunction in the connected position and damage to the plug components.

As shown in Fig. 4B, the two recesses (83b and 83d) have the same dimensions. The long edge (83e) and the beveled projection (83a) have the same height. The height of the rectangular projection (83c) is slightly less than the height of the long edge (83e) or the beveled projection (83a). Thus, the long edge (83e) and the rectangular projection (83c) are at two different levels. The design linear distance d1 mm between the midpoint of the recess (83b) and the midpoint of the recess (84b) is equal to the design linear distance d2 mm between the midpoint of the recess (83d) and the midpoint of the recess (84d).

As shown in Fig. 4C, the lower rail (81) is attached to the frame elements in the functional unit compartment by means of screws inserted through fastening holes (88) on the longitudinal edges (89a and 89b) bent at a right angle. The longitudinal edge (89a) of the lower rail (81) has two guide bushings (90) with a riveted steel ball made with the possibility of rotation inside the guide bushing (90). The lower rail (81) has two block stoppers (91) to finally stop the movement of the sliding block (1) into the block compartment in the event of a malfunction in the connected position and damage to the plug components. The lower rail (81) has a locking protrusion (92) on the longitudinal edge (89a), closer to its front end.

[Paragraph 1, page 11]

As shown in Fig. 5 and also Fig. 3, 3A, 3B, 3C, 4A and 4B, when the sliding unit (1) is completely removed from its compartment, the push button (12) is in the released state; the locking pin (21) is in the released state in the chamfered guide groove (23d); and the release pin (22) is in the pressed state in Section B (23i) of the keyhole-type groove (23g). Thus, the push button (12), the locking pin (21) and the release pin (22) are in their default states.

When the sliding unit (1) is inserted into its compartment, the locking pin (21) first hits the beveled projection (83a) and is partially pressed by the beveled projection (83a). As soon as the locking pin (21) reaches the rectangular recess (83b), the locking pin (21) goes into its released state, since it is spring-loaded, and is locked in the rectangular recess (83b). At the same time, the release pin (22) reaches the beveled recess (84b) on the release plate (84). In this way, the sliding unit (1) is locked in the test position when it is inserted into the compartment of the functional unit. The sliding unit (1) cannot move forward or backward, since the locking pin (21) is locked in the rectangular recess (83b).

To unlock the sliding unit (1) in the test position, the push button (12) is pressed. When the push button (12) is pressed, the movable plate (23) moves backward, pressing the locking pin (21) inward due to the reverse movement of the beveled guide groove (23d) on the beveled bend (23c). When the push button (12) is fully pressed, the locking pin (21) goes into a fully pressed state, in which the locking pin (21) is no longer locked by the rectangular recess (83b). At the same time, the backward movement of the movable plate (23) transfers the keyhole-type groove (23g) backward relative to the release pin (22). As a result, Section A (23h) of the keyhole-type groove (23g) is brought to the location of the release pin (22). When Section A (23h) reaches the release pin (22), the release pin (22) is released through Section A (23h) of the keyhole-type groove (23g) on the movable plate (23), since the release pin (22) is spring-loaded. The movable plate (23) is held by the step (22a) of the release pin (22). As a result, the push button (12) becomes spring-loaded and is held in the pressed state. The guide grooves (23a and 23b) facilitate the movement of the movable plate (23) back and forth relative to the sliding unit (1). Thus, when the push button (12) is pressed in the test position, the sliding unit (1) is unlocked, since the lock pin (21) is released and the release pin (22) is pressed at the same time. After this, the sliding block (1) can be moved towards the connected position or pulled out until the block release mechanism stops the sliding block (1).

[Paragraph 1, page 12]

After pressing the push button (12) in the test position, when the sliding unit (1) is pulled out from the test position, the release pin (22) hits the triangular projection (84c) and is pressed by the triangular projection (84c). As a result, the step (22a) of the release pin (22) moves inward, allowing the movable plate (23) to move forward and transferring the push button (12) from its pressed state to the released state by means of the loaded spring (26a). The forward movement of the movable plate (23) brings the Section (23i) of the keyhole groove (23g) to the location of the release pin (22), and the step (22a) hits and rests on the inner edge of the Section B (23i) of the keyhole groove (23g), while the beveled guide groove (23d) moves forward relative to the locking pin (21). In this way, the locking pin (21) is released, the release pin (22) is pressed, and the push button is released as soon as the sliding block (1) is pushed in the direction of the connected position from the test position.

After pressing the push button (12) in the test position, if the sliding block (1) is pulled out, the release pin (22) hits the beveled projection (84a) and is pressed by the beveled projection (84a). As soon as the release pin (22) is pressed inward, the action described in the previous paragraph 3 on page 9 occurs, with the release of the locking pin (21) and the push button (12).

When the sliding block (1) moves from the test position to the connected position, the action described in paragraph 1 on page 12 occurs, whereby the locking pin (21) passes the rectangular projection (83c) and locks in the rectangular recess (83d), while the release pin (22) remains pressed and reaches the open on one side chamfered recess (84d); thus, the sliding block (1) is locked in the connected position.

To unlock the sliding unit (1) in the connected position, the push button (12) is pressed. When the push button (12) is pressed, the movable plate (23) moves backwards relative to the sliding unit (1), pressing the locking pin (21) inward due to the backward movement of the beveled guide groove (23d) on the beveled bend (23c) on the movable plate (23). When the push button (12) is fully pressed, the locking pin (21) passes into a fully pressed state, in which the locking pin (21) is no longer locked by the rectangular recess (83b). At the same time, the backward movement of the movable plate (23) transfers the keyhole-type groove (23g) backwards relative to the release pin (22). As a result, the step (22a) of the release pin (22) is released through Section A (23h) of the keyhole-type groove (23g) on the movable plate (23), as described in paragraph 2 on page 9. In this case, the push button (12) is spring-loaded and held in the pressed state. Thus, when the push button (12) is pressed in the connected position, the sliding block (1) is unlocked, since the locking pin (21) is released and the release pin (22) is pressed at the same time. Then, the sliding block (1) can be pulled out from the connected position to the test position.

After pressing the pushbutton (12) in the connected position and as soon as the sliding block (1) is pulled out of the connected position, the release pin (22) hits the triangular projection (84c) and is pressed by the triangular projection (84c). As a result, the step (22a) of the release pin (22) is pressed inward, and the movable plate (23) moves forward and transfers the pushbutton (12) from its pressed state to the released state, by means of the spring (26a). The forward movement of the movable plate (23) moves the Section B (23i) of the keyhole-type groove (23g) to the location of the release pin (22), and the beveled guide groove (23d) moves forward relative to the release pin (22) and the lock pin (21), respectively, wherein the step (22a) hits and rests on the inner edge of the Section B (23i) of the keyhole-type groove (23g). Thus, the lock pin (21) is released, the release pin (22) is pressed, and the push button is released as soon as the sliding block (1) passes the connected position to the test position.

When the sliding block (1) is pulled out further, the locking pin (21) enters the rectangular recess (83b) and is released while the release pin (22) is still in the pressed state; thus, the sliding block (1) is locked in the test position when it is pulled out from the connected position. To unlock the sliding block (1) in the test position, the push button (12) is pressed. When the push button (12) is pressed, the locking pin (21) is pressed; and the release pin (22) is released, allowing the sliding block to be pulled out further.

[Paragraph 3, page 13]

As shown in Fig. 6 and 6A, the locking device (70) is a gravity-loaded device used to control the movement of the spring-loaded holder (75) of the control plug with a projection (76) attached to the rear side of the sliding unit (1). The locking device (70) is attached to the right side wall (3) of the sliding unit (1) by means of screws (71) inserted through plastic dividers and grooves (72) allowing it (70) to be moved up or down by the trigger element (23f) of the movable plate (23). The stopper (73) of the control plug of the locking device (70) extends towards the rear side (4) of the sliding unit (1) and has a beveled lower edge (74). In withdrawable units, the plug and socket parts of the control plug must be properly connected in the test position, and such connection must be maintained when the withdrawable unit is moved between the test position and the connected position. The plug load, which is applied forward during the connection, must be stopped in order to establish a proper connection in the test position. By default, the locking device (70) is in its lowest position, on the beveled edge of the trigger element (23f), blocking the projection (76) of the spring-loaded holder (75) of the control plug, while the push button (12) is in the released state. In this way, the stopper (73) of the control plug of the stopper device (70) stops the forward movement of the spring-loaded holder (75) of the control plug attached to the rear side (4) of the sliding unit (1), when the projection (76) of the spring-loaded holder (75) of the control plug hits and is blocked by the stopper (73) of the control plug. When the push button (12) is pressed, the stopper device (70) rises up along the beveled edge (23f) of the trigger element (23), and the stopper (73) of the control plug of the stopper device (70) moves upward, unlocking the projection (76) of the spring-loaded holder (75) of the control plug. As soon as the beveled lower edge (74) of the stopper (73) of the control plug rises above the level of the projection (76), it (76) gets under the beveled lower edge (74); in this way, the spring-loaded holder (75) of the control plug is no longer blocked and can move freely forward or backward when the sliding unit (1) is moved forward or backward; the beveled lower edge (74) of the stopper (73) of the control plug rests on the projection (76), the spring-loaded holder (75) of the control plug can move freely. When the push button (12) is released, the trigger element (23f) moves forward, and the locking device (70) moves downwards along the beveled edge of the trigger element (23f) under the action of the weight of the locking device (70).

As described in paragraph 1 on page 11, when the withdrawable unit (1) is in the test position and the push button is released, the spring-loaded holder (75) of the control plug is locked by the stopper (73) of the control plug; when the withdrawable unit (1) is in the test position and the push button is pressed, the spring-loaded holder (75) of the control plug is not locked by the stopper (73) of the control plug and can move freely. When the withdrawable unit (1) moves from the test position to the connected position, the push button is released and the locking device moves downwards, where the beveled lower edge (74) of the stopper (73) of the control plug rests on the projection (76); in this way, the spring-loaded holder (75) of the control plug is not locked. When the sliding unit (1) is in the connected position, the spring-loaded holder (75) of the control plug reaches its maximum in the direction of the front part, where the projection (76) extends forward beyond the beveled lower edge (74) of the stopper (73) of the control plug. When the sliding unit (1) is unlocked and moved from the connected position to the test position, the spring-loaded holder (75) of the control plug moves backward, lifting the stopper (73) of the control plug upward with the projection (76) due to the fact that the beveled lower edge (74) rests on the projection (76). When the sliding unit (1) is unlocked and moved from the connected position to the test position, the spring-loaded holder (75) of the control plug reaches its maximum in the direction of the rear; the projection (76) passes the beveled lower edge (74), allowing the stopper (73) of the control plug to move further downwards and again lock the spring-loaded holder (75) of the control plug in the test position. Said movement of the holder (75) of the control plug is described in relation to the movement of the sliding unit (1) forward and backward from the test position to the connected position and vice versa.

In addition to locking the drawer unit (1) in the connected position and the test position, it is provided with two additional locking mechanisms, i.e. an isolated locking mechanism (30) and a block release mechanism.

As shown in Fig. 7 and 7A, the isolated locking mechanism (30) is actuated by a locking lever (31) with a locking projection (31a), an operating point (31b) and an on/off projection (31c); all of them are cut and bent from a single sheet of metal. The locking lever (31) is spring-loaded by a spring (32) and is attached to the lower part (5) of the sliding block (1) by a pin (33), which allows the locking lever (31) to rotate around the pin (33). On the locking lever (31) there is a groove (34), which is used to limit the movement of the locking lever (31) by means of a pin (35). Two pins (33 and 35) are attached by means of split rings. The rear edge of the locking projection (31a) is chamfered, while the front edge is straight. The operating point (31b) has a locking opening (36). The right side wall (3) has a cutout (37) for the locking projection (31a), a cutout (38) for the operating point (31b) and a cutout (39) for the on/off projection (31c). The locking lever (31) is attached to the sliding block (1) and is spring-loaded in such a way that the locking projection (31a), the operating point (31b) and the on/off projection (31c) come out through the cutouts (37, 38 and 39), respectively.

As shown in Fig. 7B and 7C, the isolated locking mechanism (30) is provided with an on/off mechanism (40). This mechanism (40) is used to turn on or off the isolated locking mechanism (30). The on/off mechanism (40) consists of a switch (41) fixed inside the right side wall (3) of the sliding unit (1) by a rivet (42). The switch (41) can move up or down, since it is designed to rotate around the rivet (42). On the right side wall (3) of the sliding unit (1) a half punch (46) is made to stop the switch (41) from accidentally falling due to vibration or for any other reason, when the isolated locking mechanism (30) is turned on. One end of the switch (41) is bent in the form of a raised end (43) in order to pass through a curved groove (44) on the right side wall (3) of the sliding unit (1). Thus, the isolated locking mechanism (30) is engaged or disengaged by slightly pressing inward the raised end (43) and moving the switch (41) up or down. When the switch (41) is completely moved downwards, it blocks the entrance of the on/off projection (31c) through the cutout (39) in the right side wall (3) of the drawer unit (1); thus, the isolated locking mechanism (30) is disengaged, since the locking projection (31a) and the operating point (31b) remain inside the right side wall (3) of the drawer unit (1). When the switch (41) is moved upwards, it unlocks the entrance of the on/off projection (31c) through the cutout (39) and allows the on/off projection (31c) to pass through the groove (39); thus, the isolated locking mechanism (30) is engaged, since the locking projection (31a) and the operating point (31b) are outside the right side wall (3) of the drawer unit (1).

Whenever it is necessary to perform maintenance or repair of the outgoing cables or other equipment connected to the switchgear and control equipment unit, the withdrawable unit (1) is pulled out until the isolated locking mechanism (30) comes out of the functional unit compartment, wherein the isolated locking mechanism (30) is activated by lightly pressing inward the raised end (43) of the on/off mechanism (40) and moving the switch (41) upward in the curved groove (44). Then the withdrawable unit (1) is inserted until the locking lug (31a) passes the locking lug (92), where the beveled edge of the locking lug (51a) hits and passes the locking lug (92) without any further intervention. The withdrawable unit is pulled out until the front edge of the locking projection (31a) hits and stops on the locking projection (92) on the lower rail (81), from where the withdrawable unit (1) cannot be pulled out, but can be inserted until the withdrawable unit (1) is locked in the test position. When the withdrawable unit (1) is locked by the locking projection (92), the operating point (31b) is pressed inward with a finger, and the withdrawable unit (1) is pulled out to remove the withdrawable unit (1). When the locking projection (31a) is locked by the locking projection (92), a padlock can be inserted through the locking hole (36) to lock the withdrawable unit (1) in an isolated lockable position, in which the withdrawable unit (1) is completely disconnected from the incoming and outgoing circuits. When the isolated locking mechanism (30) is locked with a padlock, the drawer unit (1) cannot be inserted, which prevents the drawer unit (1) from being accidentally pushed into the functional unit compartment. After the maintenance work is completed, the padlock is removed and the operating point (31b) is pressed inward with a finger to pull out or insert the drawer unit (1). This provides additional safety for technicians performing maintenance work.

When the sliding block (1) is removed from its compartment of the functional block, it is eventually automatically locked by the block release mechanism. As shown in Fig. 8 and 8A, the block release mechanism (50) is actuated by a locking lever (51) with a locking projection (51a) and an operating point (51b), which are all cut and bent from a single sheet of metal. The locking lever (51) is spring-loaded by a spring (53) and is attached to the lower part (5) of the sliding block (1) by a pin (54), which allows the locking lever (51) to rotate around the pin (54). On the locking lever (51) there is a groove (55), which is used to limit the movement of the locking lever (51) by means of a pin (56). Two pins (54 and 56) are secured by means of split rings. The rear edge of the locking projection (51a) is chamfered, while the front edge is straight. The right side wall (3) has a cutout (57) for the locking projection (51a) and a cutout (58) for the operating point (51b) on the lower part of the right side wall (3) of the sliding unit (1). The locking lever (51) is attached to the sliding unit (1) and is spring-loaded in such a way that the locking projection (51a) and the operating point (51b) come out through the cutouts (57 and 58), respectively. When pulling out the sliding unit (1) from the compartment of the functional unit, the locking projection (51a) of the locking lever (51) hits and stops on the locking projection (92) on the lower rail (81), as shown in Fig. 4C. To unlock and completely remove the drawer unit (1), the operating point (51b) is pressed inward with a finger and the drawer unit (1) is pulled out. This provides additional safety when completely removing the drawer unit (1) from the functional unit compartment. Without such a locking mechanism, there is a high risk of the drawer unit falling down and injuring the operator. When the drawer unit (1) is inserted into the functional unit compartment, the beveled edge of the locking lug (51a) hits and is pressed inward by the locking lug (92) without any additional action.

When the drawer unit is completely removed from the functional unit compartment and inserted again, the drawer unit (1) is locked in the test position, provided that the pushbutton (12) is in the default state, i.e. in the released state. When the pushbutton (12) is pressed, the locking pin (21) is in the pressed state and the release pin (22) is in the released state. In the event that the drawer unit (1) is inserted into the functional unit compartment with the pushbutton pressed, the release pin (22) hits the beveled projection (84a) and prevents further insertion of the drawer unit (1) into the functional unit compartment. In this case, the drawer unit is pulled out and the release pin (22) is pressed with a finger to bring the locking pin (21) and the push button (12) to the released state, i.e. the drawer unit is brought to the default state, by means of the action described in paragraph 3 of page 9.

As shown in Fig. 9 and 9A, the sliding block (1) has a lock (110) of insertion, realized by using different systems of splined rounded pins (111) and square pins (112). The splined rounded pins (111) are attached to a bracket (115) with threaded holes to create a certain system of splined rounded pins (111). The splines on the splined rounded pins (111) are used to attach the pins (111). The bracket (115) is fixed inside the right side wall (3) of the sliding block (1) with two screws (117) in such a way that the splined rounded pins (111) come out through the holes on the right side wall (3) of the sliding block (1). The square pins (112) are first secured to the plate (113) having three rounded holes (119) in a row by lock nuts (118). The bracket (116) having a square hole and two rounded holes in each row is used to secure the plate (113) with the square pin (112). Each square pin (112) with the plate (113) is inserted into a square hole on the bracket (116) to ensure that the arrangement of the square pins (112) corresponds and is secured to the bracket (116) by a screw inserted into any of the two remaining rounded holes (119) on the plate. The square pins (112) should be secured closer to each other to increase the number of combinations.

When two square pins (112) with plates (113) are arranged in a row next to each other, the screws used to fasten the plate (113) to the bracket (116) cannot be fixed in a row next to each other due to lack of space. Therefore, the screws are installed in a zigzag manner using any of the two holes (119). The bracket (116) is attached to the frame member of the control and switchgear unit with two screws inserted through the holes (114) on the bracket (116).

The system of slotted rounded pins (111) fixed on the sliding block and the system of square pins (112) fixed on the bracket (116) are arranged in such a way as to allow one system of slotted rounded pins (111) to pass through the corresponding system of square pins (112) if the proper sliding block (1) is inserted into the proper compartment of the functional block. Thus, the insertion blocker (110) prevents the insertion of the sliding block into the wrong compartment of the functional block before it is locked in the test position, since the insertion blocker (110) is located closer to the rear side of the sliding block (1).

As shown in Fig. 1A, a position sensor bracket (100) is attached to the right (3) side wall of the drawer unit (1). This position sensor bracket (100) is used to attach the position sensor for receiving a signal depending on the position in which the drawer unit is located in the functional unit compartment.

When the size of the drawer unit increases in width, the stability of the movement of the drawer unit in the functional unit compartment weakens. When the drawer unit is inserted or pulled out, it may get stuck in the functional unit compartment due to improper alignment with the rails, which will negatively affect the establishment of the corresponding electrical connections. Thus, another embodiment of the invention is disclosed in Fig. 10. The second drawer unit (120) comprises two pressing and holding locking devices (20) with two push buttons (121), two locking pins (123) and two release pins (124) on the left and right side walls of the drawer unit (120). On the left and right sides of the front door retaining plate of the drawer unit (120), there are two control handles (122) for uniformly distributing the force applied to the drawer unit and for facilitating the insertion and extraction of the drawer unit.

The sliding unit (120) also comprises a set of insulated upper rails (127) and insulated lower rails (128) with two spring steel guide brackets (129) welded to each rail (127 and 128). The inner surfaces of all rails are knurled to reduce the friction created between the sliding unit (120) and the rails (127 and 128) when the sliding unit (120) is moved. Each rail (127 or 128) has openings (131) for the outgoing plugs. The front side of each rail is marked with an engraved arrow (132).

An isolated locking mechanism (125) and a release mechanism (126) of the unit are provided on the right side wall of the retractable unit (120). The actions and functional capabilities of the second retractable unit (120) are identical to the first retractable unit (1).

Claims (107)

1. A withdrawable unit for a compartment of a functional unit of a low-voltage switchgear or control equipment assembly, having a push-button operated locking mechanism in a test position and a connected position, an isolated locking mechanism for maintenance and a unit release mechanism for preventing the withdrawable unit from falling from the compartment of the functional unit of the assembly, comprising: a. a pressing and holding locking device (20) secured to the inner right side wall (3) and the inner top wall of the drawer unit (1) using brackets (25a and 25b), a cover plate (24) of the mechanism covering the actions, screws (27a), dividers (27b), pressed-in posts (27c), comprising: i. a push button (12) loaded by a spring (26a), ii. a locking pin (21) with a flange (21a) inserted through the spring (26b), the bracket (25a) with the guide sleeve (21b) and the cover plate (24) of the mechanism, and held by a nut (21c), allowing the locking pin (21) to be slightly spring-loaded, iii. a release pin (22) with a step (22a) inserted through a spring (26c) and a bracket (25b) with a guide sleeve (22b) and held by a nut (22c), allowing the release pin (22) to be slightly spring loaded, iv. a movable plate (23) having a beveled bend (23c) with a beveled guide groove (23d), guide grooves (23a and 23b), a keyhole-type groove (23g) located between the beveled guide groove (23) and the first guide groove (23a), and a rectangular bend (23e) with a trigger element (23f); b. an isolated locking mechanism (30) comprising: i. a locking lever (31) with a locking projection (31a), an operating point (31b), a groove (34) and an on/off projection (31c), wherein the locking lever (31), spring-loaded by a spring (32), is configured to rotate around a pin (33) and is limited by a pin (35) inserted through the groove (34), ii. a cut-out (37) for the locking lug (31a), a cut-out (38) for the operating point (31b) and a cut-out (39) for the on/off lug (31c) on the right side wall (3) of the drawer unit (1), iii. an on/off mechanism (40) comprising a switch (41) secured inside the right side wall (3) of the sliding unit (1) with a rivet (42) and configured to move up and down along a curved groove (44), a half-punch (46) for stopping the switch (41) from accidentally falling; c. a release mechanism (50) of the block, comprising: i. a locking lever (51) with a locking projection (51a), an operating point (51b) and a groove (55), wherein the locking lever (51), spring-loaded by a spring (53), is configured to rotate around a pin (54) and is limited by a pin (56) inserted through the groove (55), ii. a cut-out (57) for the locking lug (51a) and a cut-out (58) for the operating point (51b) on the right side wall (3) of the drawer unit (1); d. an insertion lock (110) made using various systems of slotted rounded pins (111) and square pins (112), comprising: i. bracket (115) with threaded holes, to which splined rounded pins (111) are attached, ii. a plate (113) with three rounded holes (119) in a row, to which square pins (112) are attached by lock nuts (118), and iii. a bracket (116) with a square hole and two rounded holes in each row, to which a plate (113) with a square pin (112) is attached; e. a control handle (10), a gasket (11), a front door (13), a door retaining plate (63) and a cuff gasket (62) attached to the door retaining plate (63) on the front side (2), a bracket (100) for a position sensor on the right side wall (3), a mounting plate (60) fixed inside the drawer unit (1) for mounting electrical devices, cutouts (61) for plugs and a spring-loaded holder (75) for the control plug on the rear side (4) of the drawer unit (1); f. a gravity-loaded locking device (70) which controls the movement of a spring-loaded holder (75) of a control plug with a projection (76), comprising a stopper (73) of the control plug, extending in the direction of the rear side of the sliding unit (1) and having a beveled lower edge (74); g. an upper rail (80) with relief surfaces (97) and longitudinal edges (80a and 80b) bent at right angles, and a longitudinal edge (83) formed by an additional bend of the longitudinal edge (80a), comprising: i. a beveled projection (83a), rectangular recesses (83b and 83d), a rectangular projection (83c) between two recesses (83b and 83d) and a long edge (83e) on the longitudinal edge (83), ii. a release plate (84) having a beveled projection (84a), a beveled recess (84b), a projection (84c) of a triangular shape and an open beveled recess (84d) on one side; and guide bushings (85) with a riveted rotating steel ball on the longitudinal edge (80a), iii. fixing holes (86) on the longitudinal edges (80a and 80b), and iv. the stops (87) of the block at the rear end of the upper rail (80); and h. a lower rail (81) with relief surfaces (97) and longitudinal edges (89a and 89b) curved at right angles, comprising: i. guide bushings (90) with riveted rotating steel ball and locking protrusion (92) on the longitudinal edge (89a), ii. fixing holes (88) on the longitudinal edges (89a and 89b), and iii. the stoppers (91) of the block at the rear end of the lower rail (81). 2. The drawer unit according to claim 1, in which the cuff gasket (62) attached to the rear part of the door retaining plate (63) on the front side (2) of the drawer unit (1) and the gasket (11) sealing the end of the control handle (10) improve the degree of protection (IP code) when the drawer unit (1) is fully inserted into the compartment of the functional unit. 3. The drawer unit according to claim 1, in which the movable plate (23), attached internally to the right side wall (3) of the drawer unit (1) using screws (27a), dividers (27b) and a pressed-in stand (27c), moves backwards through the guide grooves (23a and 23b) when the push button (12) is pressed and is moved forward by the spring (26a). 4. A retractable unit according to claims 1 and 3, in which the push button (12) of the movable plate (23) is attached to one end; a beveled bend (23c) with a beveled guide groove (23d) is located closer to the said end; while the other end is made with a rectangular bend (23e) with a trigger element (23f) for controlling the locking device (70). 5. A sliding unit according to claims 1 and 3, in which the guide grooves (23a and 23b), the beveled guide groove (23d) and the keyhole-type groove (23g) of the movable plate (23) are located at three different levels on the movable plate (23), while the guide grooves (23a and 23b) are located at the same level. 6. A sliding unit according to claims 1 and 3, in which the keyhole-type groove (23g) of the movable plate (23) has a Section A (23h) which is rounded, and a Section B (23i) which has the shape of a rectangle with rounded edges. 7. A sliding unit according to claim 1, in which the locking pin (21) is slightly spring-loaded and is designed to move freely when the locking pin passes through a spring (26b) held between the bracket (25a) and the flange (21a), the bracket (25a) and the guide sleeve (21b), while the locking pin (21) is held by a nut (21c). 8. A sliding unit according to claims 1, 3 and 7, in which the width of the beveled guide groove (23d) is slightly larger than the diameter of the head of the locking pin (21); and the diameter of the flange (21a) of the locking pin (21) is slightly larger than the diameter of the head of the locking pin (21). 9. A sliding unit according to claims 1, 3 and 7, in which the locking pin (21) is fully spring-loaded and is pressed when the movable plate (23) moves backwards relative to the locking pin (21) when the push button (12) is pressed, when the beveled guide groove (23d) of the movable plate (23) moves the shoulder (21a) of the locking pin (21) inward. 10. The retractable unit according to claim 1, in which the release pin (22) is spring-loaded and is designed to move freely when the release pin (22) passes through a spring (26c) held between the bracket (25b) and the step (22a), the bracket (25b) and the guide sleeve (22b), while the release pin (22) is held by a nut (22c). 11. A sliding unit according to claims 1, 3 and 10, in which the width of Section B (23i) of the keyhole-type groove (23g) is slightly larger than the diameter of the head of the release pin (22); the diameter of the step (22a) is slightly larger than the diameter of the head of the release pin (22); the diameter of the step (22a) of the release pin (22) is slightly smaller than the diameter of Section A (23h) of the keyhole-type groove (23g). 12. A sliding unit according to claims 1, 3, 10 and 11, in which the release pin (22) is additionally spring-loaded and is pressed when the head of the release pin (22) is inserted through Section B (23i) of the keyhole-type groove (23g) on the movable plate (23). 13. A sliding unit according to claims 1, 3 and 10, in which the release pin (22) is released when the movable plate (23) moves backwards when the push button (12) is pressed and brings Section A (23h) of the keyhole-type groove (23g) to the location of the release pin (22), allowing the step (22a) of the release pin (22) to exit through Section A (23h) of the keyhole-type groove (23g) and restrain the movement of the movable plate (23), wherein the push button (12) becomes spring-loaded and pressed. 14. A sliding unit according to claims 1, 3, 7 and 10, in which, when the release pin (22) is pressed by the triangular projection (84c) or the beveled projection (84a) or any other means, the step (22a) moves inward, allowing the movable plate (23d) to move forward by means of a loaded spring (26a), wherein Section B (23i) of the keyhole-type groove (23g) is brought to the location of the release pin (22), and the step (22a) rests on the inner edge of Section B (23i) of the keyhole-type groove (23g), while the beveled guide groove (23d) moves forward relative to the locking pin (21), wherein the release pin (22) is pressed and the locking pin (21) and the push button (12) are released. 15. The sliding block according to claim 1, in which the beveled projection (83a), the rectangular recesses (83b and 83d), the rectangular projection (83c) and the long edge (83e) on the longitudinal edge (83) and the release plate (84) having a beveled projection (84a), a beveled recess (84b), a triangular projection (84c) and an open on one side beveled recess (84d), and guide bushings (85) with riveted rotary steel balls, on the longitudinal edge (80a), are all located on the side on which the pressing and holding locking device (20) is attached to the sliding block (1). 16. The sliding unit according to paragraphs 1 and 15, in which the rails (80 and 81) are designated by engraved arrows (96) to indicate the front side of the rails and are formed by relief surfaces (97) on the inner surfaces of the rails (80 and 81) that come into contact with the moving sliding unit (1). 17. A sliding block according to paragraphs 1 and 15, in which the block stoppers (87) are located at the rear end of the rails (80 and 81) to stop the sliding block (1) in the event of failure in the connected position. 18. A sliding unit according to claims 1 and 15, in which the recesses (83b and 83d) have the same dimensions, while the height of the rectangular projection (83c) is slightly less than the height of the long edge (83e) or the beveled projection (83a), which ensures that the long edge (83e) and the rectangular projection (83c) are located at two different levels. 19. A sliding block according to claims 1 and 15, in which the recesses (83b and 83d), the projection (83c) and the long edge (83e) of the longitudinal edge (83), as well as the recesses (84b and 84d) and projections (84a and 84c) of the release plate (84) are formed and secured in such a way that d1 mm is equal to d2 mm. 20. The drawer unit according to claim 1, wherein the spring-loaded holder (75) of the control plug is secured to the rear side (4) of the drawer unit, and the locking device (70) is secured to the right side wall (3) of the drawer unit (1) using screws (71) inserted through dividers and grooves (72), so that the locking device (70) is able to move up and down. 21. The retractable unit according to paragraphs 1 and 20, in which the locking device (70) is in its lowest position, on the beveled edge of the trigger element (23f), blocking the protrusion (76) of the spring-loaded holder (75) of the control plug, while the push button (12) is in the released state, so that the stopper (73) of the control plug stops the forward movement of the spring-loaded holder (75) of the control plug, by default. 22. A retractable unit according to claims 1 and 21, in which the locking device (70) together with the stopper (73) of the control plug moves upward, unlocking the protrusion (76) of the spring-loaded holder (75) of the control plug, when the push button (12) is pressed; and the locking device (70) moves downward when the push button is released. 23. The retractable unit according to paragraphs 1 and 22, in which the beveled lower edge (74) of the stopper (73) of the control plug is raised above the level of the projection (76) or rests on the projection (76), the spring-loaded holder (75) of the control plug is no longer blocked and can move freely forward or backward when the retractable unit (1) is moved forward or backward. 24. A retractable unit according to claims 1 and 21, in which the spring-loaded holder (75) of the control plug is by default locked by the stopper (73) of the control plug in the test position, wherein the spring-loaded holder (75) of the control plug is designed with the possibility of free movement in the test position after pressing the push button (12); between the test position and the connected position, the push button (12) is released and the stopper moves downwards, wherein the beveled lower edge (74) of the stopper (73) of the control plug rests on the projection (76). 25. A retractable unit according to claims 1, 21 and 24, in which the holder (75) of the control plug reaches its maximum towards the front part, where the projection (76) extends forward beyond the beveled lower edge (74) of the stopper (73) of the control plug in the connected position, while the push button (12) is in the released state. 26. A sliding unit according to claims 1, 21 and 25, in which the holder (75) of the control plug moves backwards, raising the stopper (73) of the control plug with a projection (76) due to the fact that the beveled lower edge (74) rests on the projection (76), when the sliding unit is unlocked and moved from the connected position to the test position. 27. A sliding unit according to claims 1, 21 and 26, in which the projection (76) passes the beveled lower edge (74), allowing the stopper (73) of the control plug to move further downwards and lock the spring-loaded holder (75) of the control plug in the test position, in which the spring-loaded holder (75) of the control plug reaches its maximum in the rear direction when the sliding unit is unlocked and moved from the connected position to the test position. 28. A retractable unit according to claim 1, in which the rear edge of the locking projection (31a) of the locking lever (31) is beveled, and the front edge of the locking projection (31a) is straight, wherein the operating point (31b) has a locking hole (36). 29. A drawer unit according to claims 1 and 28, in which the locking lever (31) of the isolated locking mechanism (30) is attached to the drawer unit (1) and is spring-loaded in such a way that the locking projection (31a), the operating point (31b) and the on/off projection (31c) extend through the cutouts (37, 38 and 39), respectively. 30. The sliding unit according to claim 1, in which one end of the switch (41) of the on/off mechanism has a raised end (43) for passing through a curved groove (44) on the right side wall (3) of the sliding unit (1). 31. A drawer unit according to claims 1 and 30, in which the switch (41) of the on/off mechanism blocks or unlocks the input of the on/off protrusion (31c) through the cutout (39) in the right side wall (3) of the drawer unit (1), when the switch (41) is fully moved downwards or upwards, respectively; whereby the isolated locking mechanism (30) is switched off or switched on. 32. The drawer unit according to claims 1 and 30, wherein the drawer unit is drawn out until the front edge of the locking projection (31a) of the locking lever (31) hits and stops on the locking projection (92) on the lower rail (81) when the on/off mechanism is engaged, at which moment the operating point (31b) is pressed inward with a finger to draw out the drawer unit (1). 33. A retractable unit according to paragraphs 1 and 32, wherein the retractable unit is designed with the possibility of being locked by means of a padlock inserted through the locking hole (36), in an isolated lockable position when the isolated lockable mechanism is engaged. 34. A sliding unit according to claims 1 and 28, in which the beveled edge of the locking projection (31a) is struck and pressed inward by the locking projection (92) without any additional action when inserting the sliding unit (1) into the compartment of the functional unit. 35. A retractable block according to claim 1, wherein the rear edge of the locking protrusion (51a) of the locking lever (51) of the release mechanism (50) of the block is made beveled, and the front edge is made straight. 36. A sliding block according to claims 1 and 35, in which the locking lever (51) of the release mechanism (50) of the block is attached to the sliding block (1) and is spring-loaded in such a way that the locking projection (51a) and the operating point (51b) exit through the cutouts (57 and 58), respectively. 37. The sliding unit according to claim 1, wherein the sliding unit (1) is pulled out until the front edge of the locking projection (51a) of the locking lever (51) hits and stops on the locking projection (92) on the lower rail (81), at which moment the operating point (51b) is pressed inward with a finger to pull out the sliding unit (1). 38. A sliding unit according to claims 1 and 35, in which the beveled edge of the locking projection (51a) is struck and pressed inward by the locking projection (92) without any additional action when inserting the sliding unit (1) into the compartment of the functional unit. 39. The sliding unit according to claim 1, in which the bracket (115) of the insertion lock (110) is secured inside the right side wall (3) of the sliding unit (1) with two screws (117) in such a way that the slotted rounded pins (111) come out through the holes in the right side wall (3) of the sliding unit (1). 40. A sliding block according to claims 1 and 39, in which each square pin (112) with a plate (113) of the insertion lock (110) is inserted into a square hole on the bracket (116) to create a coordinated system of square pins (112) and is attached to the bracket (116) with a screw inserted into any of the remaining two rounded holes (119) on the plate (113) in a zigzag pattern, so that the square pins (112) are fixed closer to each other to increase the number of combinations. 41. A sliding block according to claims 1 and 39, in which the system of splined rounded pins (111) of the insertion lock (110), fixed on the sliding block, and the system of square pins (112), fixed on the bracket (116), are arranged so as to allow one system of splined rounded pins (111) to pass through the corresponding system of square pins (112). 42. A drawer unit according to claims 1 and 39, in which the insertion lock (110) prevents the drawer unit from being inserted into an incorrect compartment of the functional unit before it is locked in the test position. 43. The sliding unit according to claim 1, in which the bracket (100) of the position sensor is used to secure the position sensor for receiving a signal depending on the position in which the sliding unit is located in the functional unit compartment. 44. The drawer unit according to claim 1, wherein the locking and unlocking of the drawer unit (1) in the connected position and the test position, and the actions of the locking device (70) are ensured by means of a pressing and holding locking device (20). 45. The sliding unit according to claim 1, in which the push button (12) of the locking device (20) for pressing and holding is by default in the released state, the locking pin (21) is in the released state, and the release pin (22) is in the pressed state, respectively, by means of springs (26a, 26b and 26c), wherein the force of the spring (26a) is greater than the force of each spring (26b or 26c). 46. The sliding unit according to claim 1, in which the push button (12) and the locking pin (21) are in the released state, while the release pin (22) is in the pressed state, when the sliding unit (1) is completely removed from its compartment. 47. A sliding unit according to claims 1, 3, 7, 15 and 46, wherein, when the sliding unit (1) is inserted into its compartment, the locking pin (21) is partially pressed by the beveled projection (83a), released and locked in the rectangular recess (83b), while the release pin (22) reaches the beveled recess (84b) on the release plate (84). 48. A sliding unit according to claims 1, 9, 13, 14 and 47, in which the locking pin (21) is in a released state in the rectangular recess (83b), and the release pin (22) is in a pressed state in the beveled recess (84b), when the sliding unit (1) is locked in the test position; wherein the locking pin (21) and the release pin (22) become, respectively, pressed and released when the push button (12) is pressed to unlock the sliding unit in the test position. 49. A sliding unit according to claims 1, 9, 13, 14 and 47, in which the locking pin (21) is in a released state in a rectangular recess (83d), and the release pin (22) is in a pressed state in a beveled recess (84d), when the sliding unit (1) is locked in the connected position; wherein the locking pin (21) and the release pin (22) become, respectively, pressed and released when the push button (12) is pressed to unlock the sliding unit in the connected position. 50. A retractable unit according to claims 1, 3, 7, 10, 14 and 15, in which the locking pin (21) and the push button are released after pressing the push button to unlock the retractable unit and move it from the test position to the connected position, from the connected position to the test position or pull it out from the test position, while the release pin (22) is pressed by the triangular projection (84c) or the beveled projection (84a). 51. The sliding unit according to claim 1, wherein the sliding unit (1) is completely removed from the functional unit compartment and reinserted by pressing the push button (12), the locking pin (21) is in the pressed state, and the release pin (22) is in the released state, the release pin (22) hits the beveled projection (84a) and prevents further insertion of the sliding unit (1) into the functional unit compartment. 52. A sliding unit according to claims 1, 3, 7 and 10, wherein the sliding unit (1) is unlocked in the test position or the connected position by pressing the push button (12), wherein the backward movement of the beveled guide groove (23d) on the beveled bend (23c) on the movable plate (23) presses the locking pin (21) inward, and the backward movement of the keyhole-type groove (23g) on the movable plate (23) moves the Section A (23h) to the location of the release pin (22) for releasing the release pin (22), so that the movable plate (23) is held by the step (22a) of the release pin (22), wherein the push button is spring-loaded. 53. A retractable unit (120) larger than the retractable unit (1) according to claim 1, having similar functional capabilities to the retractable unit (1) according to claim 1, comprising: a. two locking devices (20) for pressing and holding with two push buttons (121); b. two locking pins (123) and two release pins (124) on the left and right side walls of the drawer unit (120); c. two control handles (122) on the left and right side of the front door retaining plate of the drawer unit (120) and d. a set of insulated top rails (127) and insulated bottom rails (128) with two spring steel guide brackets (129) welded to each rail (127 and 128). 54. The sliding block (120) according to claim 53, in which the inner surfaces of all rails (127 and 128) are ribbed to reduce friction between the sliding block (120) and the rails (127 and 128) when moving the sliding block (120). 55. A retractable unit (120) according to claim 53, in which openings (131) are retained in each rail (127 or 128) for the outgoing plugs, and the front side of each rail has an engraved arrow (132). 56. The retractable unit (120) according to claim 53, in which the isolated locking mechanism (125) and the release mechanism (126) of the unit are located on the right side wall of the retractable unit (120). 57. A method for inserting and removing a withdrawable unit for a compartment of a functional unit of a low-voltage switchgear or control equipment assembly, having a push-button-operated locking mechanism in a test position and a connected position, an isolated locking mechanism for maintenance and a block release mechanism for preventing the withdrawable unit from falling from the compartment of the functional unit of the assembly, according to paragraph 1, the method comprising the following steps: a. fixing the upper rail (80) and the lower rail (81) in the functional block compartment of the low-voltage switchgear assembly or control equipment using the fixing holes (86 and 88), holding the block stoppers (87) in the direction of the rear side of the functional block compartment, and the engraved arrows in the direction of the front side of the functional block compartment; when the two guide rails (80 and 81) are fixed in the functional block compartment, the guide bushings (85 or 90) with the riveted rotary steel ball and the locking projection (92) are on the side on which the pressing and holding locking device is located on the withdrawable block (1); b. fastening of the bracket (115) with pre-fixed slotted rounded pins (111) of the lock (110) of the insertion in a certain system, from the inner right side wall (3) of the sliding block (1); c. fastening the bracket (116) with pre-fixed plates (113) and square pins (112) of the insertion blocker (110) in a certain system, which allows passing only through a certain system of splined rounded pins (111) in the above-mentioned Step b., wherein the bracket is fixed to a suitable frame element in the compartment of the functional unit; d. inserting the appropriate sliding unit (1) into the compartment of the functional unit, wherein the push button (12), the locking pin (21) and the release pin (22) are in their default states, that is, the push button (12) is in the released state, the locking pin (21) is in the released state, and the release pin (22) is in the pressed state; e. inserting the drawer unit (1) into the functional unit compartment by pressing the push button (12), wherein the drawer unit (1) can be inserted only until the release pin (22) hits the beveled projection (84a), which prevents further insertion of the drawer unit (1) into the functional unit compartment, wherein the drawer unit is pulled out and the release pin (22) is pressed with a finger to bring the drawer unit to the default state; f. inserting the drawer unit (1) to the test position, whereby the drawer unit is locked in the test position by means of the locking pin (21) located in the rectangular recess (83b) on the upper rail (80); g. unlocking the drawer unit by pressing the push button (12) in the test position, and moving the drawer unit into the connected position or pulling it out of the test position; h. after pressing the push button (12), when the sliding unit is pushed in the direction of the connected position or pulled out from the test position, the release pin (22) is pressed by the triangular projection (84c) or the beveled projection (84a), respectively, whereby the forward movement of the movable plate (23) brings the locking pin (21) and the push button (12) to the released state; i. inserting the drawer unit (1) to the connected position, whereby the drawer unit is locked in the connected position by means of the locking pin (21) located in the rectangular recess (83b) on the upper rail (80); j. unlocking the drawer unit by pressing the push button (12) in the connected position, whereby the drawer unit is pulled out in the direction of the test position until the drawer unit is locked in the test position; k. unlocking the drawer unit (1) in the test position by pressing the push button (12), whereby the drawer unit is pulled out until it is locked by the release mechanism (50) of the unit, provided that the isolated locking mechanism (30) has not been activated; 1. pressing the operating point (51b) inwards with a finger and pulling the sliding block (1) out of the functional block compartment when it is locked by the block release mechanism (50). m. In case of any maintenance work, Steps n. to s. must be followed. n. unlocking the drawer unit in the test position and pulling the drawer unit out until the isolated locking mechanism comes out of the functional unit compartment; o. switching on the isolated locking mechanism (30) by lightly pressing inwards on the raised end (43) of the on/off mechanism (40) and moving the switch (41) upwards in the curved groove (44); p. inserting the sliding block (1) until the locking protrusion (31a) passes the locking protrusion (92), where the beveled edge of the locking protrusion (51a) hits and passes the locking protrusion (92); q. pulling out the drawer unit until the front edge of the locking lug (31a) hits and stops on the locking lug (92) on the lower rail (81), whereby the drawer unit (1) cannot be pulled out but can be advanced until the drawer unit (1) is locked in the test position; r. locking the drawer unit (1) by inserting a padlock through the opening (36) to lock the drawer unit (1) in an isolated lockable position in which the drawer unit (1) is completely disconnected from the incoming and outgoing circuits; s. after completing the maintenance work, remove the padlock and press the operating point (31b) with your finger inwards to pull out or insert the drawer unit (1).