AU2012201755A1 - Switch Actuator Assembly - Google Patents

Abstract

An electrical load break switch with a remotely actuable linear actuator assembly operatively connected to cause rotation of a manually operable handle of the switch between an OFF and an ON position. The linear actuator is configured to receive actuation commands from a control module. The control module could comprise a wireless transceiver such as a wireless modem adapted to connect with wireless communication networks to receive actuation commands. AvIANUAL A+A ~iQ /Q P/A WOCKABL L6 E LATCH- -IS Figure lb Figure la Figure Ic

Description

GRIFFITH HACK PATENT AND TRADE MARK ATTORNEYS SPECIFICATION OF PROVISIONAL PATENT APPLICATION COUNTRY Australia TYPE Provisional - Normal NUMBER 2011901445 DATE 18 April 2011 TITLE SWITCH ACTUATOR ASSEMBLY OWNER NGK Stanger Pty Ltd 2657464 1 (GHMatter) PaSaS AU -2 SWITCH ACTUATOR ASSEMBLY Technical Field 5 The field of the invention is medium and high voltage safety switches, in particular load break switches and apparatus for operation and locking of such switches. Background of the Invention 10 It is essential to provide safety switches in medium and high voltage electricity supply systems, for example in electricity substations, transmission systems and at usage sites such as factories, buildings or industrial is complexes. Load break safety switches enable isolation of the power supply in the case of emergency or if required for safety reasons during maintenance and construction activities. Sulphur hexafluoride (SF 6 ) gas insulated switches are commonly used as load break switches for such 20 applications. Such switches can be manually operated, to connect and disconnect power supply, or operated remotely from a control centre. A known type of manual gas insulated load break switch has 25 a rotating arm which is rotatable between a first position where the switch will be ON and a second position where the switch will be OFF to isolate the power supply. Such switches can also be provided with a locking mechanism to inhibit switching between OFF and ON. An example of such 30 as switch and locking mechanism is disclosed in Australian patent application no 2007200963 in the name of Energy Support Corporation, the disclosure of which is incorporated here by reference. Such switches are often located toward the top of power poles. Thus, requiring a 35 person to climb the pole or use a lift to reach the manual switch actuation arm. It is know in such cases to provide an intermediate switch actuator, known as a mid pole 2635781 _2 (GHMatters) P83485.AU 18o4m -3 actuator, connected to the manual switch actuation arm and mounted low enough on the pole to be actuated by a person on or near the ground with the aid of a long pole. It should be appreciated that is generally undesirable for 5 the manual actuator to be easily reached from or near the ground as an easily accessible manual actuator is more likely to be accidentally or mischievously operated. Some known gas insulated switches are adapted to be 10 operated automatically and can be controlled remotely such switches use dedicated internal motors or solenoids for driving the switch. In some applications it is desirable to convert from using 15 manually actuated gas insulated switches to automatic or motor driven switches. This requires replacement of manual switches with motor driven switches which must be done by qualified personnel, known as special live line crew, because of safety requirements and risks. Further, 20 the power supply must also be interrupted while the switch conversion takes place. This means that conversion from manual to motor driven switches can be a costly and time consuming process. 25 Summary of the Invention According to one aspect of the present invention there is provided an actuator assembly for a manual load break switch, the load break switch being of a type having a 30 manually rotatable handle where when the handle is in a first position an electrical path through the switch is connected and when the handle is in a second position the electrical path through the switch is disconnected, the remote operable actuator assembly comprising: 35 a linear actuator adapted to be operatively connected to cause rotation of the manually operable handle between the first and second positions; 2635781 2 (GHMatters) P83485.AU 1soani1 -4 a control module is configured to receive actuation commands and in response to received actuation commands drive the linear actuator to cause rotation of the handle between the first and second positions. 5 The control module can comprises a controller configured to control driving of the linear actuator in response to received actuation commands and a power module. 10 The control module can further comprise a wireless transceiver adapted to receive actuation commands. For example, the wireless transceiver can be a wireless modem adapted to connect with wireless communication networks. 15 In an embodiment the control module is adapted to communicate with a central control centre. In an embodiment the controller is programmable. 20 The actuator assembly can further comprise a manual override mechanism to enable manual disconnection of the actuator assembly to enable manual operation of the handle. For example, the manual override mechanism can comprise a releasable fastener which enables disconnection 25 of the linear actuator from the handle. In an embodiment the control module power supply includes a re-chargeable power supply. 30 An embodiment of the actuator assembly further comprises sensors to detect an operational state of the switch. The sensors can be adapted to detect the handle position. For example, the sensors can be micro-switches. 35 In an embodiment the linear actuator is a screw ball drive type linear actuator. 2635781 2 (GHMatters) P83485.AU iiom - 5 In an embodiment the linear actuator is operatively connected to the handle of a gas switch by connection to a manually operable handle of a mid pole actuator assembly which, in turn, is operatively connected to the switch 5 handle to cause operation of the switch. Brief Description of the Drawings Figure la shows a manually operable load break switch, 10 Figure lb shows an example of an actuator assembly of the present invention, Figure lc shows the actuator assembly of Figure lb is connected to the load break switch of Figure la, Figure 2 is a block diagram of the control module, and Figure 3 shows detail of switch state sensors of the actuator assembly shown in Figure 1b. 20 Detailed Description Embodiments of the present invention provide a actuator assembly for a manual load break switch, suitable for load 25 break switches of a type having a manually rotatable handle whereby when the handle is in a first position an electrical path through the switch is connected and when the handle is in a second position the electrical path through the switch is disconnected. The actuator assembly 30 comprises a linear actuator and a control module. The linear actuator is adapted to be operatively connected to cause rotation of the manually operable handle between the first and second positions. The control module is 35 configured to receive actuation commands and in response to received actuation commands drive the linear actuator to cause rotation of the handle between the first and 2635781_2 (GHMatters) P83485,AU1804111 -6 second positions. An advantage of embodiments of the actuator assembly is that the assembly can be easily retrofitted to an existing 5 manual load break switch to convert the switch for automatic operation. For some switches the actuator assembly can even be installed without requiring any power interruption. 10 Figure la shows a manually operable load break switch 100. The load break switch has a handle 105 which is rotated between a first position (shown) where the electrical path is connected through the switch, otherwise known as the ON position, and a second or OFF position where the i5 electrical path through the switch is disconnected. The connection and disconnection of the electrical path is effected by movement of a moveable electrode into and out of engagement with a stationary electrode, to connect and cut off the electrical path respectively. However, the 20 operation of the switch is not critical to the invention and the invention can be used with any type of manually operable switch where the connection and disconnection of the electrical path is manually effected by operation of a handle. 25 In the embodiment shown the load break switch 100 is connected to a manual mid pole actuator 110 via a downrod 120, so that operation of the mid pole actuator 110 will cause operation of the switch 100. The downrod 120 is 30 connected to the rotatable handle 112 of the mid pole actuator 110 and to the manual operation handle 105 of the switch 100. A mid pole actuator 110 is typically provided to enable manual operation of the switch 100 from the ground via the mid pole actuator 110 using an elongate 35 pole or rod to move the mid pole actuator handle 112. An actuator assembly 130 according to an embodiment of the 263578 1_2 (GHMatters) P83485.AU 1sto4mi present invention is shown in Figure lb and the actuator assembly is shown operatively connected to the switch 110 in the example shown in Figure 1c. The actuator assembly 130 has a linear actuator 140 and a control module 150. s In the embodiment shown the actuator assembly also includes an optional mid pole actuator assembly 110a. The mod pole actuator 110a is substantially identical to the mid pole actuator 110 and includes minor modifications. It is also possible to connect embodiments of the actuator 1o assembly 130 of the invention to existing mid pole actuators 110. Some optional modifications may also be made to the existing mid pole actuator 110 to improve operation with the actuator assembly. is The control module 150 is configured to receive operation commands and cause actuation of the linear actuator 140 to cause rotation of the rotatable handle 112 in response to the operation commands, for example, to cause connection or disconnection of the switch 100. 20 The linear actuator 140 of the actuator assembly 130 is connected to the handle 112 of the mid pole actuator 110a. The linear actuator 140 can be any suitable type of linear actuator, for example hydraulic, pneumatic, screw ball 25 drive or mechanical type linear actuators. Embodiments using any linear actuator type are envisaged within the scope of the present invention. In the embodiment shown the linear actuator 140 is a ball 30 screw drive type linear actuator the motor of which is driven by the control module 150 to operate the linear actuator. In the embodiment shown the motor and ball screw drive mechanism are housed in the cover 142. In this embodiment the control module 150 controls DC power 35 supply to the motor to drive the motor of the linear actuator 140, supplying power to the motor to cause movement of the linear actuator arm 145, and reversing 2635781_2 (GHMatters) P83485.AU 18i0411 -8 polarity of the DC power supply to the motor reverses direction of travel of the linear actuator arm 145. For example, in response to a command the control module 150 controls power to be supplied to the motor of the linear 5 actuator 140 to move the arm 145 which causes rotational movement of the handle 112 of the mid pole actuator 110a and, in turn, the down rod 120, to operate the switch 100. An example of an embodiment of the control module is shown 10 in Figure 2. The control module 150 comprises a controller 220, a power module 230 and an input/output (I/O) interface 240. The control module 150 can also include a transceiver module 210. 15 The I/O interface enables manual input of actuation commands and can provide outputs to operators indicative of operating conditions and switch status. The I/O interface may be of any suitable configuration. In the example shown the I/O interface includes buttons or 20 switches 242 for inputting commands to the controller 220, for example actuation commands to connect or disconnect the switch, manual reset, power off etc. Lights 244, for example LED lights, can be provided for output to the operator. For example, lights may indicate switch status 25 (ON or OFF), power status (AC OK, battery OK), controller status (CPU OK) etc. Although buttons and lights are used in the embodiment shown other interfaces may also be used, for example, tough screens, key pads, LCD displays etc. The I/O interface may also include an audio output. An 30 advantage of simply using buttons and lights is these can enable a simple, low cost and robust I/O interface to be provided. The controller 220 is configured to control driving of the 35 linear actuator in response to actuation commands. The controller 220 can be implemented using any suitable hardware device or circuit. In an embodiment the 2635781 2 (GHMatters) P83485.AU M0o - 9 controller is a circuit including a processor which is programmable to enable control functions to be modified after installation. For example, the controller can include a microprocessor, programmable logic controller s (PLC), electronically programmable read only memory (EPROM), Field programmable gate array (FPGA) or other type of programmable device into which instructions, executable by the device, in response to input data can be implemented. The controller may also include memory for 10 storing data, such as operation log data, switch states, operational states, and actuation counts. In an embodiment the controller is configured to receive actuation commands and control the actuation of the linear 15 actuator in response to the actuation commands. The programmed actions executed in response to an actuation command can vary between embodiments based on control actions required for operation of the linear actuator. In some embodiments the controller is further configured to 20 perform functions such as monitoring the switch state, recording state changes, actuation data and other operational data. In an embodiment the control module can include an 25 interface to enable programming on the controller 220 installed in the field. For example, the controller may include a port to enable data communication between the controller 220 and a device such as a laptop computer or other suitable device to download instructions to the 30 controller 220. In some embodiments the controller may also have a wireless interface which enables downloading of interactions. In an embodiment where the control module is connected to a control centre, a data connection to the control centre may be utilised for downloading 35 instructions to the controller 220. The power supply 230 of the control module is configured 2635781_2 (GHMatters) P83485.AU 1810401 - 10 to supply power to the controller and linear actuator. In the embodiment shown on Figure 2 the power module is supplied with 240V AC mains power. A transformer module 232 converts the AC power supply to DC power supply for s driving the DC motor of the linear actuator, powering the hardware of the control module, and charging an optional battery 236. The battery 236 can act as a backup power supply to enable 10 the actuator assembly to operate when the AC power supply is cut off. For example, during an emergency or power failure it may be desirable to disconnect the switch 100, but the mains AC power supply is cut off. The battery 236 can power the actuator assembly to enable operation even is in the absence of mains power. The battery provides power to the control module hardware and DC motor drive 234 to operate the linear actuator 140. The battery 236 may be able to provide power to the actuator assembly for a period of time which is dependent on the battery capacity 20 and number of times the actuator assembly is operated. A minimum requirement may be one operation of the linear actuator 140. This will enable disconnection of the switch 100 in the case of a power failure or emergency using the actuator assembly. In some embodiments the 25 controller may be adapted to automatically operate the actuator assembly to disconnect the switch 100 under battery power in the case of an unexpected failure of AC power supply. For example, if it is unsafe or undesirable to have an electrical connection through switch connected 30 when power is re-established, then the switch may be automatically disconnected. The battery 236 may be recharged once mains AC power is restored. The power module 230 can include a DC motor drive module 35 234 configured to supply DC current to the motor of the linear actuator 140. In the exemplary embodiment shown in Figures la-c the linear actuator is a screw ball drive 2635781 2 (GHMatters) P83485AU 104111 - 11 type linear actuator driven by a DC motor. The polarity of the DC current supply determines the direction of drive. In this embodiment the DC motor drive 234 of the control module 150 is configured to supply DC power of the 5 required polarity under control of the controller 220. Power is supplied to the motor of the linear actuator via a cable 143. The DC motor drive 234 can also be adapted to identify 10 when load current exceeds a threshold value indicative of the linear actuator being physically inhibited from operation, for example if the arm 112 is locked using a manual locking mechanism 180, and cease driving the linear actuator 140. The controller 220 may also be adapted to is prohibit further operation of the actuator assembly where a load current threshold value has been exceeded, also known as a current overload lockout feature. A warning may also be provided in the form of a warning light on the I/O interface 240 of the control module 150 or a message 20 transmitted to an operator to alert the operator to the problem. The controller 220 may inhibit further operation of the actuator assembly until manually reset by an operator. For example, an operator attending the site may manually check the switch, mid pole actuator and actuator 25 assembly to determine the cause of the current overload lockout, rectify any problem and reset the current lockout at the control module 150 to enable operation of the actuator assembly again. 30 The I/O interface 240 may also include an isolation switch to enable manual lockout of the actuator assembly. For example, where maintenance is being performed on power lines downstream of the switch, it may be desirable to ensure that the actuator assembly is manually inhibited 35 from operation. The isolation switch may be adapted to be locked into an OFF position to prevent any accidental switching ON of the actuator assembly and subsequent 2635781 2 (GHMatters) P83485.AU 18/04m1 - 12 operation of the actuator 140 to connect power through the switch 100. The control module 150 can be provided with a transceiver s module 210 to enable remote operation. In some embodiments the control module 150 can be adapted to enable a transceiver module to be installed in the control module either on initial installation or retrofitted. This also has the advantage of enabling the transceiver 10 module to be selected based on operator requirements and, if necessary, upgraded in accordance with operator requirements and advances in technology. The transceiver module 210 may be a wired or wireless is transceiver, or include both wired and wireless capability. For example, where the actuator assembly is to be installed near a power supply substation, a wired connection to the substation control centre 260 may be provided. For example, this wired connection may connect 20 the actuator assembly into the local SCADA control network for the substation to enable actuation commands to be sent automatically via SCADA control or under control of the substation operator. It should be appreciated that a wired connection to a control centre may be impractical 25 unless the switch 100 is located near such a control centre. It is therefore desirable to enable the actuator assembly for remote operation using wireless communication, for example via communication networks or a local short range wireless connection. 30 In an embodiment the transceiver module 210 is wireless including a radio frequency (RF) transceiver which uses any suitable wireless transceiver using any suitable communication protocol. For example, the wireless 35 transceiver may be a radio modem, Bluetooth, WIFI, GSM, 3G transceivers etc. Other wireless communication technologies may also be used, for example infra red (IR) 2635781 2 (GHMatters) P83485.AU wio4m - 13 transceivers. Any transceiver and communication protocol can be chosen for the control module and compatible operator modules for transmitting remote operation commands constructed. In practice a transceiver type and s communication protocol will typically be chosen based on a convenient or mandated transceiver type and communication protocol for operator modules. The transceiver module 210 can include all necessary processing hardware, software and firmware for receiving and interpreting transmitted 10 signals and converting received data into actuation commands or other commands for the controller 220. In an embodiment the transceiver unit is a Trio radio modem, using DNP3 or MODBUS protocols. These protocols is are compatible with current operator control units used to provide commands to remote operable switches known in the prior art. Installing a Trio radio modem using DNP3 or MODBUS enables the actuator assembly of the present invention to be used without requiring additional or 20 upgraded operator control units. However, any wireless transceiver may be used with compatible operator units. For example, a 3G or Bluetooth transceiver may be provided to enable the actuator assembly to be operated via a smart phone application, laptop or tablet computer, either 25 locally via Bluetooth or via a 3G communication network. In some embodiments, more than one transceiver type and communication protocol may be used. For example, a control module may be configured to receive remote 30 operation commands via a 3G telecommunication network using Internet protocols and also configured to receive remote operation commands via a short range RF transceiver using a proprietary or standard signalling protocol. Such embodiments may be convenient where it is desirable to 35 enable the remote operable actuators to be operated by both a legacy system and via new technologies such as a smart phone application. 26357812 (GHMatters) P83485.AU1,o4/n - 14 The transceiver can also be used to transmit data to the operator units, for example switch status, actuator assembly status, operating parameters, battery status, s locking status etc. Such data may be transmitted in response to a request signal received from an operator. In an alternative embodiment the control module may include a receiver only. In this embodiment the control 10 module is adapted for one way communication only, to receive remote operation commands, and is not adapted to transmit any acknowledgement or other data in reply. The actuator assembly can be provided with sensors adapted 15 to identify the actuator handle position and, in turn, whether the switch is ON or OFF. In the embodiment shown the sensors are micro switches 170 which indicate the position of the mid pole actuator handle 112. the mid pole actuator handle is provided with a switch arm 175 20 which makes engages with one of two switch contacts 172, 174 depending on the position of the mid pole actuator handle 112. A signal is transmitted to the controller indicating which contact is engaged. A detailed view of the micro switches 170 is shown in Figure 3. An advantage 25 of sensing the switch state based on position of the mid pole actuator arm 112 is that the switch state can be determined even if the actuator assembly 130 is physically disconnected from the handle 112. However, alternative embodiments of sensors to determine switch state as 30 envisaged. In the embodiment shown the actuator arm 145 is connected to the handle 112 by a releasable fastener, for example a pin, which can be manually removed to disconnect the arm 3S 145 and handle 112, for example if manual operation of the mid pole actuator is required or during routine maintenance of the actuator assembly 130. While the 2635781 2 (GHMatters) P83485.AU 18o411 - 15 actuator arm 145 and handle 112 are disconnected, any movement of the actuator arm 145 will have no effect on the handle 112 and therefore not operate the switch. The pin 114 may be attached to the actuator assembly 130 via a s cable or lanyard to avoid the pin 114 being lost when removed. A holder 148 for storing the pin when removed may also be provided. Any suitable releasable fastener may be used to provide the manual disconnection functionality. The pin 114 can also be hard wired to the 10 controller to provide a signal indicative of whether the pin 114 is engage with the actuator arm 145 and handle 112 or disengaged as stored in the holder 148. This indication can be used to feed back, via the controller, to the operator whether or not the switch is enabled for 15 automatic/remote operation or is in a manual operation mode. In an embodiment the arm 145 of the linear actuator 140 is connected to the handle 112 in a manner that allows some 20 relative movement between the linear actuator arm 145 and the handle 112. For example in the embodiment shown in Figure 1 a slot 147 is formed in the actuator arm 145 and a member 114 (for example a pin) extends outwardly from the handle 112 to engage with the slot 147. A small 25 amount of movement of the actuator arm 145 can occur before the member 114 engages with the end of the slot 147 and further movement of the arm 145 causes the handle 112 to move. This play can be advantageous for ease of installation of the remote operable actuator assembly as 30 this play allows some tolerance in the placement of the actuator arm. This can also have an advantage of reducing manufacturing costs as this play can allow manufacture of components with bigger tolerance. A further advantage is that this enables a safety margin in the moment of the 35 actuator arm 145 before movement of the handle 112. For example, the actuator arm 145 may move a small distance before inhibited by the end of the slot and a current 2635781 2 (GHMatters) P83485.AU M04111 - 16 overload condition occurring, this may be advantageous for safety of operation for some DC motor drives. The embodiment shown in Figures la-c the actuator assembly 5 130 is connected to a mid pole actuator assembly 110. An advantage of this is the actuator assembly 130 can be installed without needing to interfere or cut off the switch 100. This can significantly reduce installation costs, time and interruption to service, which may be 10 avoided altogether. This also enables simple and quick reversion to manual operation if necessary, for example during an emergency or maintenance. However, alternative embodiments are envisaged. The actuator assembly 130 can be connected directly to the switch handle 105 to cause 15 movement of this handle 105 to operate the switch. This embodiment may be more difficult to install as access to the switch handle 105 can be obstructed by other switch components as well as typically being at higher elevation than a mid pole installation. Installation may also need 20 to be performed by specially qualified personnel and require power through the switch to be cut off during installation for safety reasons. In another embodiment the actuator assembly 130 may be 25 connected to the down rod 120 to move the down rod to cause operation of the switch 110. An advantage of this type of installation is that, similarly to connecting to a mid pole actuator, power through the switch may not need to be interrupted during installation. However, this 30 embodiment has a disadvantage as reversion to manual operation may not be as simple as where the actuator assembly 130 is connected to a mid pole actuator 110. However, this and other alternative embodiments are envisaged within the scope of the invention. 35 It will be understood to persons skilled in the art of the invention that many modifications may be made without 2635781 2 (GHMatters) P83485.AU 1o81"1 - 17 departing from the spirit and scope of the invention. In the claims which follow and in the preceding description of the invention, except where the context s requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further 10 features in various embodiments of the invention. It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the 15 common general knowledge in the art, in Australia or any other country. 2635781_2 (GHMatters) P83485.AU 18/O4M

Claims (14)

1. An actuator assembly for a manual load break switch, the load break switch being of a type having a manually s rotatable handle where when the handle is in a first position an electrical path through the switch is connected and when the handle is in a second position the electrical path through the switch is disconnected, the remote operable actuator assembly comprising: 10 a linear actuator adapted to be operatively connected to cause rotation of the manually operable handle between the first and second positions; a control module is configured to receive actuation commands and in response to received actuation commands 15 drive the linear actuator to cause rotation of the handle between the first and second positions.

2. An actuator assembly as claimed in claim 1 wherein the control module comprises a controller configured to 20 control driving of the linear actuator in response to received actuation commands and a power module.

3. An actuator assembly as claimed in claim 2 wherein the control module further comprises a wireless 25 transceiver adapted to receive actuation commands.

4. An actuator assembly as claimed in claim 3 wherein the wireless transceiver is a wireless modem adapted to connect with wireless communication networks. 30

5. An actuator assembly as claimed in claim 2 wherein the control module is adapted to communicate with a central control centre. 35

6. An actuator assembly as claimed in claim 2 wherein the controller is programmable. 2635781 2 (GHMatters) P83485.AU 13mi - 19

7. An actuator assembly as claimed in claim 1 further comprising a manual override mechanism to enable manual disconnection of the actuator assembly to enable manual operation of the handle. 5

8. A remote operable actuator assembly as claimed in claim 7 wherein the manual override mechanism comprises a releasable fastener which enables disconnection of the linear actuator from the handle. 10

9. An actuator assembly as claimed in claim 1 wherein the control module power supply includes a re-chargeable power supply. 15

10. An actuator assembly as claimed in claim 1 further comprising sensors to detect an operational state of the switch.

11. An actuator assembly as claimed in claim 10 wherein 20 the sensors are adapted to detect the handle position.

12. An actuator assembly as claimed in claim 11 wherein the sensors are micro-switches. 25

13. An actuator assembly as claimed in claim 1 wherein the linear actuator is a screw ball drive type linear actuator.

14. An actuator assembly as claimed in claim 1 wherein 30 the linear actuator is operatively connected to the handle of a gas switch by connection to a manually operable handle of a mid pole actuator assembly which, in turn, is operatively connected to the switch handle to cause operation of the switch. 35 2635781 2 (GHMatters) P83485.AU1ai4ii