. Electric railway journal . as been found that an interruption of 5 or 6 cycles isgreat enough to cause the galvanometer or vane type ofrelay to drop. The changeover switching device developed consistsof two 75-amp., 4500-volt, double-pole oil switchesmounted back to back on separate panels and mechan-ically interlocked by means of bell cranks and connectinglinks, as shown in the accompanying halftones. Re-ferring to the first wiring diagram switch A acts as atie between the 3400-volt, 60-cycle motor-generator setsand the outgoing 3400-volt, 60-cycle signal feeder switch is normally
. Electric railway journal . as been found that an interruption of 5 or 6 cycles isgreat enough to cause the galvanometer or vane type ofrelay to drop. The changeover switching device developed consistsof two 75-amp., 4500-volt, double-pole oil switchesmounted back to back on separate panels and mechan-ically interlocked by means of bell cranks and connectinglinks, as shown in the accompanying halftones. Re-ferring to the first wiring diagram switch A acts as atie between the 3400-volt, 60-cycle motor-generator setsand the outgoing 3400-volt, 60-cycle signal feeder switch is normally closed. In case of failure ofthe normal power supply the trip coil located under theoil switch handle unlatches switch A, allowing the coilspring C to operate the mechanism. This opens switchA and closes switch D. The latter switch ties the 2300-volt, 60-cycle emergency feeder to the step-up trans-former, the high side of which is connected to the 3400-volt signal feeder bus. The trip coil on switch A is actuated as follows:. VIEWS OF CHANGEOVER SWITCHES SHOWING INTERLOCKING LEVERS rent, the power being obtained from motor-generatorsets fed from transformers connected to the 11,000-volt,three-phase, 25-cycle traction bus. An emergency sourceof signal power is supplied from the 2300-volt, 60-cyclelighting feeders of the Philadelphia Electric Company,and the problem was to provide a means by which thesignal load could be automatically transferred from themotor-generator sets to the emergency power supply, thetransfer to be made at such speed that the signal relayswould not be affected. There are on the market several electric switchingdevices designed to change the supply of power fromone source to another in the event of interruption ofeither source. However, apparatus of this type isusually designed for use on low-voltage circuits and isnot designed especially for high-speed operation. Thepresent condition involved a high-voltage system and one Referring to the second wiring di
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