Patent GB-431594-A (GB)
Title: Improvements in or relating to electrical systems of lift control
IPC: B66B1/46
Filed: 1934-03-26
Abstract: 431,594. Electric lift-control systems ; thermionic valve circuits. GENERAL ELECTRIC CO., Ltd., Magnet House, Kingsway, London, and CHUBB, A. A., c/o General Electric Co., Stoke, Coventry. March 26, 1934, No. 9373. [Class 78 (ii)] [See also Group XL] A lift-control system is provided with time delay apparatus comprising a source of direct current, a condenser, a resistance, a relay, and a cold-cathode gas-discharge tube, so connected that the tube is in a state of relaxation oscillation. The delay apparatus may be used (1) to ensure that the lift does not re-start immediately it has stopped at a floor (2) to return the lift to any particular floor, (3) to shut down the motor generator supplying power to the lift motor if no calls are received, and for other purposes. In the arrangement shown a relay TP is operated by the discharge of a condenser A through a neon tube B, discharge taking place when the voltage across the tube electrodes is approximately 170 volts. The condenser is in parallel with the tube and relay, and the combination is connected in series with two resistances RA, RB to a D.C. supply. In order to ensure that the delay period during which the condenser is being charged is constant, the relay TP is arranged to close a contact tp<1> which short-circuits the tube B and allows the condenser to discharge itself completely each time, instead of merely discharging until the tube reaches its entinguishing potential of 130 volts. The resistance RB is used only when a long delay is required ; at other times it is short-circuited by the closing of contacts nr<2>, sd<3> when relays NR, SD are energized. As long as the lift is in use a relay C is energized through a lead 2. When the lift stops this relay is de-energized and releases contact c<3> which completes the delay circuit from the D.C. supply through another contact g<2> normally held closed by a relay G. The time relay TP is thus energized, after a time lag depending on whether both resistances RA, RB are in circuit or RA only, and operates contact tp<2> which completes the circuit of the driving magnet TS of a stepby-step telephone-type switch having contact banks TS1 .... TS5, the circuit for TS being completed through bank TS1. Prior to the lift stopping at a floor an inductor relay S closes contact s<1> and energizes relay SD which controls contacts sd<1>, sd<2>. Contact sd<1> completes a holding circuit for relay SD through lead 10, gate switches JA .... JF, lead 11 and contact tp<2>. When the lift is stopped at a floor an inductor relay T closes a contact t<1> and relay NR is energized through contact sd<2> of relay SD. Contact nr<1> of relay NR breaks the circuit of the lift motor LM, so that this motor cannot be driven as long as NR is energized. Contact nr<2> of relay NR, and contact sd<3> of relay SD short circuit the resistance RB, so that the first delay period, i.e. that employed to hold relay SD energized, is determined by resistance RA only. After the first operation of relay TP to release relays SD and NR the contacts nr<2>, sd<3> are opened and resistance RB is brought into circuit, so that, if no further calls are made for the lift and relay C therefore remains de-energized, the relay TP is operated after a longer delay period. Each time relay TP is energized the magnet TS operates the contact banks TS1 &c. When wiper TS3 reaches its fifth contact it is connected temporarily to lead 4 which operates a storage device in the lift controlling apparatus whereby the lift is sent to any particular floor at which it is required normally to stay. A relay D is also energized through lead 4 and operates a contact d<1> which prevents relay C from being re-energized. If the lift is still not required relay TP intermittently energizes magnet TS to operate the contact banks TS1 &c., until wiper TS4 leaves the end of its connected contacts thus breaking the circuit of relay G, and opening contact g<1> in the circuit of the motor DM of the Ward Leonard set supplying power to the lift plant. Contact g<2> of relay G is also opened and breaks the circuit of the timing delay device so that magnet TS is no longer operated. When a further call is made for the lift relay C is again energized and contact c<2> completes a circuit for magnet TS through bank TS2 and interrupts contact ts so that the bank switch steps by self-interruption until the wiper of TS2 rests on its first contact and the switch stops. In the meantime contact c' energizes relay G and contact g<1> re-starts the generator set. The whole cycle of operations can then be repeated. Bank TS5, which may or may not be necessary, provides indications to the lift attendant of lapses of time. The leads 5, 6, 7 may be used to operate controlling devices, e.g. for inter-working between batteries of lifts. The control system employed may be that described in Specification 423,805, [Group XXXVII].