DEVICE FOR PROTECTION OF ELECTRICAL INSTALLATIONS AGAINST ABNORMAL OPERATING CONDITIONS Russian patent published in 2005 - IPC

FIELD: electrical engineering, in particular, relay protection and automatics equipment of power systems, applicable in construction of microprocessor protection and automation of lines, synchronous motors and transformers.

SUBSTANCE: the device has the first and second converters of input signals, whose inputs are designed for connection to the contacts of the starting units from the relays of protection and automatic equipment, control current voltage source, interlock contacts, switch opening and closing coils, each of the converters uses a p-n-p-transistor, the second arm of the voltage divider in the mentioned converters is formed by a third resistor, the actuating units in the converters of input signals are made with the use of an optopair with a light-emitting diode and a phototransistor, and a loading resistor in the device output circuit, the transistor emitter is connected to the anode of the light-emitting diode of the optopair, to the cathode of the mentioned diode and to the second resistor, the transistor collector is connected to the cathode of the light-emitting diode of the optopair and to the other contact of the respective starting unit, the transistor base is connected to the midpoint of the voltage divider and to the diode anode, the free lead of the second resistor is connected to the positive terminal of the control current voltage source, and the outputs of the converters of input signals are designed to control the relay protection and automatics equipment and connected to the inputs of the AND gate, the output of the AND gate is connected to the input of the time-delay element, and the output of the time-delay element is designed for signaling of a fault of the switch control circuits via the relay protection and automatics device.

EFFECT: provided a self-check of the switch control circuits at maintenance of adjustment against false operation at ground faults of the connecting cable, as well as signaling of a fault of the switch control circuits.

1 dwg, 1 tbl