US2625672A - Controller for electric motor driven apparatus - Google Patents

Description

Jan. 13, 1953 V T 2,625,672

CONTROLLER FOR ELECTRIC MOTOR DRIVEN APPARATUS Filed Sept. 20, 1951 12.5 R LLL I REVERSE. TR

mcu I85 lq START L Patented Jan. 13, 1953 CONTROLLER FOR ELECTRIC MOTOR DRIVEN APPARATUS Arthur '1. Calvert, Manhasset, N. Y., assignor to Cutler-Hammer, Inc., Milwaukee, Wis., a corporation of Delaware Application September 20, 1951, Serial No. 247,478

'7 Claims. 1

This invention relates to improvements in controllers for electric motor driven a paratus.

Controllers embodying the invention are especially advantageous for control of printing presses but are not limited to such application.

An object is to provide a controller of the class described which affords plugging of the motor after a relatively long forward inch but no plugging after a relatively short forward inch.

Another object is to provide a controller of the class described which provides high starting torq e for regular operation and for forward and reverse inching.

A more specific object is to provide a controller of the class described which uses a time delay mechanism to determine whether the motor is to be plugged following forward inching.

Another object is to provide a controller of the class described which starts forward inching and running at high torque and also plugs at high torque, and

Another object is to provide a controller of the class described which after forward high torque inching changes the motor to approximately half running speed as governed by the aforementioned time delay mechanism.

Other objects and advantages of the invention will hereinafter appear.

The accompanying drawing illustrates one embodiment of the invention which will now be described, it being understood that the embodiment illustrated is susceptible of various modifications without departing from the scope of the appended claims.

In the drawing, the figure shows schematically and diagrammatically a preferred embodiment of the invention.

Referring to the drawing, the same shows a polyphase slip ring induction motor M having its primary P supplied from lines L L and L through conventional reversing switches F and R, each being of the triple pole electromagnetically operated type. The secondary S of the motor M has for its circuit delta connected speed regulating resistors r 1' and r as will later appear are adjustable through the medium of sliders l, 2 and 3 which bridge different points of said resistors with segments 4, 5 and B respectively. These delta connected resistors are arranged in a well known manner as shown in the drawing. Point 25, Which is the junction of resistors r and T is connected to a secondary terminal S while point 26, the junction between resistors r and 1 is connected directly to secondary terminal S The junction between resistors r and T or point 21,

is connected to the secondary terminal S through winding [3 of a plugging relay PR to be hereinafter fully explained. Also the speed regulating resistors are provided with electroresponsive control switches IA and T. These electroresponsive switches are of the triple pole type and provide for control for all of the speed regulating resistors in a given manner. As shown, switch T affords, by normally open contacts 23*, 23 and 23 thereof, connections to taps l, 8 and 9 of resistors r r and r respectively, and switch IA provides through normally open contacts 24, 24 and 2 thereof connections to segments 4, 5 and 6 respectively. All of the contacts of switches IA and T effect shorting-out of certain predetermined portions of resistors r 1 and 1' whenever their respective actuating windings are energized.

The drawing also shows a plugging relay PR depicted as comprising a double ended arm I0 movable to bridge either of two pairs of stationary contacts ll and M The relay has for moving its arm H3 into the position shown in full lines a winding l2 to be connected across lines L and L through contacts 22 and 22 of the reversing switch R, such influence of said winding l2 being opposed by the influence of the above-mentioned winding l3 in the secondary circuit of the motor. Also the relay PR has a windin l4 adapted to move the arm IIJ into the dotted line position, said arm when not subjected to the influence of one or another of windings l2 and [4 being adapted to remain in the position to which it was last moved.

Connected to line L through a normally closed momentary open stop button I 5, is one side of the normally open momentary closed start button 18. The other side of said start button I6 is connected thru the coil ll of electromagnetic switch CR and the normally closed contacts 22 of the electromagnetic reversing switch R to line L In parallel circuit arrangement with start button I6 are normally open contacts I'l of the electromagnetic switch CR, said contacts I l providing a maintaining circuit when said start button is released. Connected between a point common to the left hand contact of start button I 6, the right hand contact of stop button IS, the left hand contact of contacts ll and the left hand contact of contacts I 8 of the momentary three position reversing switch l8 are normally open contacts Il and a normally open momentary closed inch button l9; said contacts ll and button l9 being connected in parallel circuit arrangement. The right hand contact of contacts 48 is connected to a point common to a lead wire of each of the coils 2B and 2! of the electromagnetic switches F and TR respectively. The other lead wires of coils 20 and 2i are each connected to a point common to the coil I? and the right hand contact of the normally closed contacts 22 The above-mentioned reversing button I8 is also composed'of three lower contacts la all of which are simultaneously bridged when the but ton I8 is held. in its lowermost position. The left hand one of said contacts l8 is connected to a point common to the left hand contact :of contacts I8- of said button l8, the left hand contact of inch button l5 and the right hand contact of contacts li The center contact of contact 18 is connected to a point common to the right hand contact of inch button [9, the left hand contacts of contacts ll and I l the right hand contact of stop button l5 and the left hand contact of start button l6, while the right hand contact of contacts 18 is connected to the line L through the normally closed contacts 28 and winding 22 of the electromagnetic switch R. The normally open contact 26 of switch F is connected between line L and a point common to the left hand contact of contacts 253 and the right hand contact of contacts [8 of the reversing button 18.

'The electromagnetic switch TB is a timing relay consisting of a winding 2i, normally open contacts 21 normally closed contacts 21* and a timing mechanism represented by the dashpo-t 2I. The normally closed contacts Zi are connected from line L through winding 23 of the electromagnetic switch T to a point common to the right hand contact of contacts 18* and contacts 20 and 2.6 The normally open contacts '2l are connected from line L through winding .24 of the electromagnetic switch IA through the .normally open contacts 11 to a point common to winding 23, contacts 20 and Zll and the right hand contact of contacts 18 In series with each other but in electrical parallel with respect to winding 24 and contacts ll are winding 14 and contacts II when .arm Iii is in thefull line position (as shown) When arm is in the dotted line position, a circuit is completed from line L through the stationary contacts li and arm ii) to a point common to the right hand contacts of contacts l'l 18 and 26 The circuit operates as follows: Upon depressing the start button l6, current flows from line L through buttons l and I 6, winding I? and normally closed contacts 22 to line L The energization of winding l1 closes contacts .I l H and 11. The closing of contacts Il allows current to flow from line L through button l5, contacts He, contacts 18* of switch l8 and thence in parallel through windings 12B and El, and contacts 22 to line L The closing of contact li provides a maintaining circuit for start button it so that when said button I5 is released, the starting circuit through winding I! is maintained.

The energization of winding 20 affords current to the primary P of motor M through the closing of contacts 2%, Zii and 25 The closing of contacts 29 provides current flow from line L through contact 20 winding 23 and the then closed contacts 2! to line L Contacts 2t initially remain closed even though winding at is energized, and are opened after a predetermined time delay as determined by the timing mechanism 2. Thus the motor M has started with contacts 23 23 and 23 closed providing high starting torque as the result of shorting-out a certain portion of resistors r r and T As the motor M accelerates, and the timing mechanism 'P from the supply lines L L and L 2l has run a sumcient length of time to allow contacts Zi to close and contacts 2N to open, winding is is deenergized by said opening of contacts 21*. Upon the closing of contact Zi a circuit is provided from line L through contacts Ed and H winding 2 and contact Zi to line "The motor secondary starting connections are disconnected by the deenergization of winding 23 while the operating speed connections are applied as the result of the closing of contacts .251 :25 and Et Also due to the closing of contacts :2 this the current flow from line L through contacts 28 stationary contacts H and arm ill, Winding is and contacts 25* to line L Upon energization of winding is, the plunger I 3 is caused to move upwardly thereby swinging the arm i5 into the dotted line position. Movement of arm .5 ii into the last mentioned position affords deenergization oi winding i i. The motor is thereby running at a forward operating speed according to the predetermined setting of the sliders l, '2 and 3 on the resistors r r and r respectively.

If it is desired to stop the motor M, the stop button 55 is depressed. This opens various circuits which results in the deenergization of windings ll, 2c and 2 i. The deenergizat'ion of winding 28 causes the main contacts 28 28 and 26 to open, eifecting disconnection of motor primary The contacts 22 are closed by this deenergi'zation thereby providing a circuit from line L through the stationary contacts M and arm is (in dotted line position), contacts 26" and winding 22 to line L.

The energization of winding 22 and the resultant closing of contacts 2%, 22 and 22, applies reverse power to the motor primary P in a well known manner. Also contacts 22 are opened by winding 22 so that it is impossible for winding 2% 2i and H to be energized while the reverse winding 22 is in operation. Simultaneous with the application of reverse power to the motor primary P, is the closing of contacts 2 l and the opening of contacts 2P li H and IF. The closing of contacts El energizes winding 23 through the arm is (still in the dotted line position) so that high torque plugging is accomplished by the shorting-out of the above-mentioned portions of resistors 1' 1' and T when the contacts 23 23 and 23 are closed. The opening of contacts ll" disconnects winding 24 from the source of power.

The locking winding is of the PR relay has been the only winding of said relay which has remained energized since the plunger i has caused arm in to assume the dotted line position. Said winding 13 remains energized whenever power, either forward or reverse, is applied to the motor secondary and efiects plunger lZ to try to keep it in its lowermost position or away from the arm iii. The energization of winding 22 also closes contacts 22 which in turn provides for subjection of winding 12 to line voltage during the plugging operation. In the practical application of the invention, contacts 22 are constructed to close shortly after the closing of contacts 22 22 and 22 to insure the energization of the looking winding is before the energization of winding l2, so that at the start of the plugging operation, arm it will remain in the dotted line position.

As the motor is plugged and slows down, the motor secondary current decreases in accordance with the speed of said motor M. This decrease in secondary current results in a decrease in current flow through winding is until it reaches a predetermined low value wherethe winding I2; having -'a"constantcurrentflow, dominates the plunger Ii! and causes "it to move upwardly and return arm to 'to the heavy line position. This causes *the-deenergization of winding22 resulting inthe "tions as when'the startbutton IE is pressed as above-described in detail; except that by pressing 'the'inch button It the winding 1'! is never energized thereby keepingwinding 24 from everbeing energized. Therefore, when thehigh starting "torque winding23 is deenergized by the opening of contactsElE-all of the resistance'of resistors 1' r and r are in the secondary circuit'allowing the motor to comeup'to approximately-only half running speed, a condition which is very ideal during inching. When the'contacts 2 l are closed the arm it is moved into the dotted line position thus'providing a maintaining circuit for contacts 29 when the inch button it is releasedgthe result,

of course, being plugging of the motor as above described. 'If the inch button 19 is not depressed long enough to allow contacts it to close and contacts 2t to'open, arm'lii will remain in the heavy line position and no plugging will result when button i9 is released. The motor will then come to rest due'to the inherent friction'in the motor and the driven machine.

' The reverse button l8 as above-mentioned is a three position'switch. It is biasedto normally bridge contacts w but may be held in the lowermosttpositiom'where it bridges contacts l8 or it may be held in the intermediate position which is represented by the dotted line between the sets of contacts. If said button [8 is'depressed to its mid position (broken line) it functions the same as stop button [5. If the motor M is running in the forward direction and button 18 is depressed to bridge contacts I8 and is then released, the same operation will result as is caused by depressing and releasing stop button 15. These functions above-mentioned are not the normal uses for button 18 since the stop button serves the same purpose. However, said button 58 is primarily used for reverse inching or jogging by bridging contacts Id of button l8 when the motor is at rest. A circuit is thereby completed from the line L through stop button Hi, the right hand and center contacts of contacts 13 closed contacts Zii and winding 22 to line L This applies reverse power to the motor M causing the motor to run in a reverse direction. Another circuit is completed through button from line L through the two right hand contacts of contacts l8 winding 23 and closed contacts 2 I to line L Thus the motor is operated at high torque in the reverse direction. The windings 2t, 2 I, ll, 24, 12, I3 and M are not energized on the reverse inch so that as long as the reverse button I 8 is bridging contacts I 8 the motor M will run in the reverse direction at high torque. When said button [8 is released the motor will come to rest due to the inherent friction of said motor and the driven machine.

I claim:

1. In a system for plugging an electric motor, comprising in combination, means including an electroresponsive switch for connecting said motor to a source of electrical energy for running,

'electroresponsive switch is deenergized,

transfer switch having means acting as a result a' second electroresponsive switch energizable to connect said motor to a source of electrical energy for-plugging, and control means for controlling connection of the operating winding of said second eiectroresponsive-switch to its source comprising time delay means operable a predeter- ,mined timefollowing energization of said first mentioned switch and switch means acting as a result of operation of said time delay means to effect energization of the operating winding of saidsecond'electroresponsive switch when the first mentioned electroresponsive switch is deenergized; said switch means having means responsive tomotor slow-down during plugging to deen- 1ergize said-second electroresponsive switch.

2. In a'system-for inching an electric motor, comprising in, combination; means including an electroresponsive switch for connecting said motor to a source of electrical energy for inching, a second electroresponsive switch energizable to connect said motor to a source of electrical energy for plugging, andrcontrol means for controlling connection of the operating winding of said second electroresponsive switch to its source comprising a time delay relay having an operating winding energizable in response to operation of said first mentioned means'and having normally open contacts, and a transfer switch having an 'electroresponsive winding energizable as a result 'of closure of saidrelaycontacts to effect energization of the operating winding of said second electroresponsive switch when the first mentioned said of motor slow down during plugging to deenergize said second electroresponsive switch.

3.111 a system for plugging an electric motor, in combination, a motor, a source of electrical power supply, means including an electroresponsive switch for connecting said motor to said source for running, a second electroresponsive switch energizable to connect said motor to said source for plugging, and control means for controlling connection of the operating winding of said second electroresponsive switch to said source comprising time delay means operable a predetermined time following energization of said first mentioned switch and. switch means acting as a result of operation of said time delay means to effect energization of the operating winding of said second electroresponsive switch when the first-mentioned electroresponsive switch is deenergized, said switch means having means responsive to motor slow-down during plugging to deenergize said second electroresponsive switch.

4. In a system for inching an electric motor, in combination, a motor, a source of electrical power supply, means including an electroresponsive switch for connecting said motor to said source for inching, a second electroresponsive switch energizable to connect said motor to said source for plugging, and control means for controlling connection of the operating winding of said second electroresponsive switch to said source comprising a time delay relay having an operating winding energizable in response to operation of said first mentioned means and having normally open contacts and a transfer switch having an operating winding energizable as a result of closure of said relay contacts to effect energization of the operating winding of said second electroresponsive switch when the first mentioned electroresponsive switch is deenergized, said transfer switch having means acting as a result of motor slow-down during plugging to deenergize said second electroresponsive switch.

5. In a system for inching an electric motor, in combination, a motor, a source of electrical power supply, means including an electroresponsive switch for connecting said motor to said source for inching, a second electroresponsive switch energizable to connect said motor to said source for plugging, and control means for controlling connection of the operating winding of said second electroresponsive switch to said source comprising a time delay relay having an energizing winding responsive to operation of said first mentioned means and having normally open contacts, and a transfer switch having a contactor and first, second and third operating windings, said first winding being energized as a result of closure of said relay contacts to operate said contactor from one position to another to afford energization of said second electroresponsive switch, said second winding being energized as a result of operation of said second electroresponsive switch and tending to operate said contactor to said one position, said third winding being energized as a function of motor speed and preventing operation of said contactor to said one position pending motor slow-down to a given speed during plugging.

6. In a system for inching an electric motor, comprising in combination, means including an electroresponsive switch for connecting said motor to a source of electrical energy for inching, a second electroresponsive switch energizable to connect said motor to a source of electrical energy for plugging, and control means for controlling connection of the operating winding of said second electroresponsive switch to said source comprising a time delay relay having an energizing winding responsive to operation of said first mentioned means and having normally open contacts and a transfer switch having first, sec-- 0nd and third electroresponsive windings and a contactor, said first winding being energizable as a result of closure of said relay contacts to effect energization of the operating winding of said second electroresponsive switch when the first mentioned electroresponsive switch is deenergized, said second and third windings being energizable with current from said source and the motor secondary respectively and producing opposing effects on said contactor during plugging to afiord deenergization of said second electroresponsive switch when the energizing current of said third winding reaches a predetermined value during motor slow-down.

7. In a system for plugging an electric motor, comprising in combination, means including an electroresponsive switch for connecting said motor to a source for running, a second electroresponsive switch energizable to connect said motor to a source of electrical energy for plugging, control means for controlling connection of the operating winding of said second electroresponsive switch to its source comprising time delay means operable a predetermined time following energization of said first mentioned switch, means including a third electroresponsive switch having an operating winding energizable to effect greater torque during plugging than during normal run of the motor, and switch means acting as a result of operation of said time delay means to effect energization of the operating windings of said second and third electroresponsive switches when said first mentioned electroresponsive switch is deenergized, said switch means having means responsive to motor slow-down during plugging to deenergize said second electroresponsive switch.

ARTHUR T. CALVERT.

No references cited.

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