| 摘要 |
A voltage sensing device automatically scales the source and network phase voltages of a power distribution system having one of two operating voltages for input to a network protector relay and also automatically scales a voltage for operating the trip and close circuit of the circuit breaker in the network protector. A latching tap select relay only switches the system voltages to the lower operating voltage input taps of step down transformers after a short delay if all the system voltages are in the lower operating range. A diagnostic circuit verifies proper switch position and voltages before closing output contacts to connect the scaled voltages to the relay and circuit breaker.
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