The Record Electrical Co. Ltd. Broadheath Altrincham Cheshire UK

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The firm displayed a working model of a portion of a town lighting system to demonstrate the Record Remote Operated Selective Switching Units. Two different systems were shown: (a) selectivity through a pilot wire and (b) selectivity by interruption of the main circuit. Both seems could be operated from a central point, either manually or by time-switch. Eight combinations of signal were available. - APLE Conference Programme Glasgow 1945

Street Lighting Control: A Description Of The "Record" Control System

System devised after careful consideration of the advantages claimed by several existing systems. The greatest advantage claimed is that no additional wiring is required. In many districts, pilot wires are already in existence, while where new cables are being laid the cost of the extra core is almost negligible. Therefore they developed a scheme which would be simple in optionation, and therefore cheap, and would use the pilot wire to transmit impulses so would be free from external interference.

The outcome was the "Record" Remote operated Selective Switching Unit. It does not depend on an operating current which is different in frequency or voltage from that alreadying existing on the L.T. network, which overcomes the trouble of maintenance, since it does not require technical knowledge outside the sphere of lighting.

It depends on its operation purely upon an impulse of approximately 5 seconds along the pilot wire, the potential being any existing L.T. phase voltage at normal frequency or D.C.

The Transmission Of Impulses

The simplest form of impulse transmitter is an ordinary push button connecting phase to pilot and operated by hand to switch "on" and "off" the whole of the lighting. This suffers from the disadvantage that there is no visual indication of the lighting position and relies on the human element for its operation at any time. This is overcome by housing in one box the appropriate number of receiving units with control lights, which indicate the lighting position at any time. In addition, there is a time switch which times the impulses to suit the requirements. A push button is provided for use in emergencies, such as fog conditions etc.

The Receiving Unit

This is a solenoid operated switch which has been designed to have its contacts open or closed in any predetermined sequence with a maximum cycle of eight different positions, after which the cycle is repeated. This cycle is brought about by the solenoid plunger operating an eight-toothed lantern pinion which carries a cam, which in turn opens or closes the contacts, according to the shape of its periphery. Therefore by fitting different shapes of cam, any combination of lighting can be arranged to suit up to eight different conditions. This can be used both to accommodate partial switching off for skeleton lighting after midnight, and for gradual switching on, so that the full lighting load is not suddenly switched on without warning. The contacts of the switches are of pure silver and there is considerable pressure between the contact faces when they are closed. A pair of contacts would stand several hundred thousand operations while controlling a load of 400 watts without undue burning. There is also a patented mechanism coupling the pawl on the solenoid plunger to the lantern pinion, or rotor, which prevents the latter from overshooting. This makes it possible to put plenty of reserve power into the solenoid without fear of its momentum carrying the rotor round too far. A switch wound to operate off 230 volts, 50 periods, will still operate on a voltage as low as 160. Also, as part of the mechanism is a non-return pawl on the rotor to prevent it for either move round and getting out of position due to vibration, or being pushed in the reverse direction due to pressure from the contacts. The contact operating cam is easily changed at any time if a different programme of lighting is required. The whole is housed in a neat brass cover which is designed to overcome open-air conditions.

Operation on Non-Pilot Schemes

The system can be operated on a two-wire system. The limitations are (i) the two wires must be for lighting distributions i.e., not general service mains and (ii) that the operation of the scheme depends upon a momentary interruption of the circuit, it cannot be used to give suitable control of mercury vapour lamps. Discrimination of lighting is acheived by breaking the supply to the two wires, which allows the solenoid plungers to fall, and then quickly restore the supply which energises the solenoid, thus turning the cam around to the next position. The break in the two-wire circuit can still be initiated from the central control point by an impulse.

Public Lighting #39, October-December 1945

A working model of a portion of a town lighting system is exhibited to illustrate some applications of the Record Remote Operated Selective Switching Units. The units can be applied to provide selective switching of lights on two different systems of wiring: (a) Selectivity through a pilot wire and (b) Selectivity by interruption of the main circuit when no pilot wire exists. It can be operated from a central point, either manually or by a time switch, and be arranged to give any pre-arranged combination of lighting up to a maximum of eight combinations. On the non-pilot operated scheme, the operating coils of all the switches are energised during the time the lights are on - the burden is very low, being 3.5 V.A. at 0.26 power factor (less than 1W). It is now possible to control two or three circuits from one unit e.g. in changing over from mercury vapour to tungsten filament lamps. - APLE Conference Programme London 1946

References:
APLE Conference Programme Glasgow 1945
APLE Conference Programme London 1946
APLE Conference Programme Southport 1947

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