GB2199704A

GB2199704A - Mining vehicle battery switching installation

Info

Publication number: GB2199704A
Application number: GB08717348A
Authority: GB
Inventors: Geoffrey William Purdy
Original assignee: Oldham Crompton Batteries Ltd
Current assignee: Oldham Crompton Batteries Ltd
Priority date: 1986-07-22
Filing date: 1987-07-22
Publication date: 1988-07-13
Anticipated expiration: 2007-07-22
Also published as: GB8717348D0; GB2199704B; GB8617870D0

Abstract

A switching installation for the power supply battery of an electrically driven mining vehicle consists of an interrupter (18) at or near the middle of the chain of cells (10) forming the battery and interlocked with plug and socket connectors (16, 17) at the terminals of the battery, so that the plugs cannot be withdrawn from the sockets without opening the interrupter and reducing the terminal potentials to zero. The switch may be operated in response to optical, electrical, mechanical, pneumatic or hydraulic sensing. <IMAGE>

Description

MINING VEHICLE BATTERY SWITCHING INSTALLATION This invention relates to switching installations for the multi-cell power supply batteries of electrically powered mining vehicles. Electrically powered vehicles for use in mines are provided with power supply batteries comprising, for example, a chain of 50 single cells connected in series to produce a voltage of 100 volts and a power output of 25 KW or more. One or more plug and socket devices is or are provided in the output from the battery for connecting it to a load, such as a traction motor.

It has been customary to provide the battery with a switching installation comprising two circuit breakers in a flame proof switch box, one circuit breaker being connected to the positive and one to the negative end of the chain of cells, a corresponding pair of plug and socket devices for carrying the positive and negative supplies from the battery, and an interlock between the circuit breakers and the plug and socket devices so that the plugs cannot be withdrawn from the sockets without opening the circuit breakers. Even when the circuit-breakers are open, the battery connections in the switch box remain live so that the box cannot be opened without exposing a pair of live terminals, with the attendant fire risk. To avoid this, an interrupter may be provided at or near the middle of the chain of cells in the battery.Usually this will be at the far end of the battery from the plug and socket connector. Provided that this interrupter is actuated, the battery terminals can be brought to zero potential to enable the switch box to be opened safely. In practice, it is possible for an operator to forget to actuate the interrupter, particularly when it is located at a distance from the plug and socket connectors, and the installation is complicated and expensive.

According to the invention, a switching installation for a multi-cell power supply battery of an electrically driven mining vehicle consists essentially of an interrupter at or near the middle of the chain of cells forming the battery, at least one plug and socket connector in the output from the battery, and an interlock between the interrupter and the connector or connectors such that the plug or plugs cannot be withdrawn from the socket or sockets without first breaking the chain of cells by opening the interrupter and thereby reducing the potentials at the battery terminals to zero. By thus providing the interlock between the mid-point interrupter and the connector or connectors and omitting the circuit breakers connected to the ends of the battery, the installation is considerably simplified as compared with the prior art, with a consequent saving in cost.

Furthermore, on opening of the interrupter, the battery terminals are at once reduced to zero potential without requiring the operator to remember an additional control, with a beneficial effect on safety.

The interlock may be mechanical, electrical, optical or pneumatic or hydraulic. A mechanical interlock can be inexpensive and convenient if the interrupter is located at the same end of the battery as the plug and socket connectors. Electrical, optical or pneumatic or hydraulic interlocks may be more convenient where the interrupter is located at a distance from the connectors. A plurality of interrupters may be used if desired, located at different points in the chain of cells.

Specific embodiments of the invention will now be described in more detail by way of example and with reference, to the accompanying drawings, in which: Fig. 1 is a diagrammatic plan view of a multi-cell battery for a mining vehicle with a switching installation according to the invention, Fig. 2 is a diagram of a mechanical interlock, Fig. 3 is a diagram of an electrical interlock, Fig. 4 is a diagram of an optical interlock, and Fig. 5 is a diagram of a pneumatic or hydraulic interlock for use in the installation of Fig. 1.

The battery illustrated diagrammatically in Fig. 1 consists of a chain of single cells 10, say 100 in number, connected in series by dual leads 11 and contained in a battery casing 1. The positive and negative terminals 14,15 at the respective ends of the chain of cells 10 are provided with respective plug and socket connectors 16,17. At the middle of the chain of cells 10 is arranged an interrupter 18 contained in a flame proof switch box 19 and provided with an operating handle 20. An interlock indicated diagrammatically by lines 21 is provided between the interrupter 18 and the connectors 16,17, so that the plugs cannot be withdrawn from the sockets of the connectors 16,17 without first breaking the chain of cells by opening the interrupter 18 and hence reducing the potential at the battery terminals 14,15 to zero.

The interlock 21 may be mechanical, optical, electrical or pneumatic or hydraulic in nature, as mentioned above. Fig. 2 illustrates diagrammatically a mechanical interlock in which the external operating handle 20 of the interrupter is arranged so that the plugs of the plug and socket connectors 16117 cannot be removed from the socket or sockets until the handle 20 has been moved to the open position, e.g. because a bar 22 connecting the plugs cannot be moved until the handle 20 has been moved to the open position. Such a mechanical interlock is convenient where the switch box 19 containing the interrupter 18 is mounted adjacent to the plug and socket connectors 16,17, as shown in Fig. 1.

An alternative electrical interlock system is illustrated in Fig. 3. One or both of the plug and socket connectors 16,17 is provided with a limit switch 23 having a sensor 24 projecting through the socket 25 to contact the plug 26. On commencement of removal of the plug 26 from the socket 25, the sensor 24 will extend to break the circuit and cut supply of current to a solenoid (not shown) which normally holds the interrupter 18 in the closed position.

An alternative-optical interlock system is illustrated in Figure 4, where a mirror 27 is secured to the plug 26 so as to complete an optical circuit between optical fibre cables 28,29 when the plug is in position in the socket 25. On commencement of withdrawal of the plug 26, the optical circuit is broken. This is arranged to cut the supply of current to a solenoid (not shown) which normally holds the interrupter 18 in its closed position.

A third alternative interlock system using fluid pressure (pneumatic or hydraulic) is illustrated diagrammatically in Fig. 5.

In this case, a piston and cylinder device 30 is arranged so that its piston 31 contacts the plug 26 when the latter is in position in the socket 25, but on commencement of withdrawal of the plug the piston 31 can extend to release fluid pressure from a pneumatic or hydraulic actuator (not shown) which normally holds the interrupter 18 in the closed position.

In a further refinement of the present invention, the flame proof switch box 19 housing the interrupter 18 is provided with a door which is also interlocked with the interrupter 18 and the plug and socket devices 16,17 so that the door cannot be opened until the interrupter is in the open position and the plugs removed from the sockets.

In an alternative mechanical arrangement a system of keys may be used to control operation of the switch 18 and opening of the socket connectors 16 and 17. Such a modified arrangement no longer requires a physical interconnection between the switch 18 and the sockets 16 and 17 so that the switch box 19 need not be located in close physical proximity to the socket connectors 16 and 17. The switch box 19 may be located at the end of the battery casing remote from the socket connectors 16 and 17. In one such arrangement the switch 18 includes a rotary element which may be held in the off position by the engagement of two locks one positive and one negative, each releasable by the insertion of a respective key. Each of the sockets 16 and 17 has a hinged door which may be held in a closed position, preventing access to the socket, by means of a lock operable by one of the keys used to control the locks on the switch 18. When the switch 18 is moved to the off position the switch locks engage the rotary element and the keys may then be removed and inserted into the locks controlling access to the battery sockets. On releasing the locks to provide access to the sockets the keys become captive in the socket locks so that the keys are not available to permit the switch 18 to be switched on. When the plug and socket connections are completed the socket locks may be re-locked so that the plugs are held in locked engagement with the sockets and the keys may then be released from the locks.The same two keys may then be engaged in the switch locks so as to unlock the rotary element of the switch 18 and permit rotation of the switch to the on position. By use of such an arrangement the two keys necessary to unlock the rotary member of the switch 18 to allow the switch to be switched on, are only available when the socket locks are in the locked closed position either holding a protective door in position to conceal access to the socket or alternatively are holding plugs in engagement with the sockets. The two locks on the switch 18 are. arranged to hold the two keys captive while the switch locks are in the open position and the switch in the on state. The plugs cannot be withdrawn from the sockets until the switch is rotated to the off position permitting movement of the switch locks to a condition holding switch in the off state when the keys can then be released from the switch and used on the socket locks to release the plugs.

The invention thus provides a simplified and inexpensive switching installation for the power supply battery of an electrically driven mining vehicle.

Claims

Claims:

1. A switching installation for a multi-cell power supply battery of an electrically driven mining vehicle, which installation comprises an interrupter at or near the middle of the chain of cells forming the battery, at least one plug and socket connector in the output from the battery, and an interlock between the interrupter and the connector or connectors such that the plug or plugs cannot be withdrawn from the socket or sockets without first breaking the chain of cells by opening the interrupter and thereby reducing the potentials at the battery terminals to zero.

2. A switching installation according to Claim 1, wherein said interlock comprises one or more keys arranged to actuate a switch element in the interrupter and release of said connector or connectors, the key or keys being captive in the interrupter unless the switch element is in the open position.

3. A switching installation according to Claim 2, wherein each plug and socket connector includes a lock controlling access to the socket, the lock being arranged to hold the key captive when the lock is in the open condition permitting access to the socket.

4. A switching installation according to Claim 3, wherein each socket is provided with a cover device to prevent access when no plug is engaged, the lock for each socket being arranged when in the closed condition to hold said cover or a plug in engagement with the socket thereby preventing access to the socket.

5. A switching installation according to Claim 1, in which said interlock comprises a mechanical link between a switch element of the interrupter and a movable part of each connector whereby movement to withdraw the plug or plugs from the socket or sockets causes movement of the switch element to an open condition.

6. A switching installation according-to Claim 1, wherein the interrupter is housed in a flame-proof switch box with an external operating handle which is arranged so that the plug or plugs cannot be removed from the socket or sockets until the handle has been moved to the open position of the interrupter.

7. A switching installation according to Claim 1, wherein the interlock is electrical.

8. A switching installation according to Claim 7, wherein a limit switch is arranged to be actuated on commencement of removal of the or each plug from its socket, such actuation of said limit switch being arranged to cut the supply of current to a solenoid which normally holds the interrupter in the closed position.

9. A switching installation according to Claim 1, wherein the interlock is optical.

10. A switching installation according to Claim 9, wherein a mirror is arranged on the or each plug and socket connector so as to make an optical circuit between two optical fibre cables when the connector is fully home but to break the optical circuit on commencement of removal of the or each plug from its socket, and breaking of the optical circuit is arranged to cut the supply of current to a solenoid which normally holds the interrupter in its closed position.

11. A switching installation according to Claim 1, wherein the interlock is pneumatic or hydraulic.

12. A switching installation according to Claim 11, wherein a pneumatic or hydraulic piston and cylinder device is arranged so that its piston is actuated on commencement of removal of the or each plug from its socket, so as to release fluid pressure from a pneumatic or hydraulic actuator which normally holds the interrupter in the closed position.

13. A switching installation according to any one of the preceding claims wherein the interrupter is housed in a flame-proof box with a door which is also interlocked with the interrupter and the plug and socket connector or connectors so that the door cannot be opened until the interrupter is in the open position and the or each plug removed from its socket.

14. A switching installation substantially as hereinbefore described with reference to Figure 1 and Figure 2 or any of Figures 3, 4 or 5 of the accompanying drawings.