DEVICE FOR PROTECTION OF SYNCHRONOUS ELECTRIC MOTORS FROM EMERGENCY OPERATING CONDITIONS Russian patent published in 2006 - IPC H02H7/08 

FIELD: electrical engineering.

SUBSTANCE: the device has a power unit, relay coil with a make contact connected to the control circuit by a motor contactor, voltage stabilization unit built around high- and low-voltage stabilizer diodes, temperature protective unit with three transistors and temperature-sensitive resistors built in the stator winding of the electric motor, voltage asymmetry protective unit, transducer of power mains asymmetry voltage, actuator with a transistor, protective unit against emergency braking with an operational amplifier and a transistor, warming unit, the protective unit against emergency braking has resistance strain gauges installed on the components of electric motor fastening to the base and resistors connected to the resistance strain gauges according to the four-arm bridge circuit, whose input is connected to the low-voltage stabilizer diode, and the output is connected to the input of the operational amplifier of the protective unit against emergency braking in parallel with a capacitor, the input of the operational amplifier via an additional resistor is connected to the base of the transistor of the protective unit against emergency braking.

EFFECT: enhanced efficiency of protection of a three-phase synchronous motor and expanded functional potentialities of the protective device.

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