DEVICE FOR COMPLEX PROTECTION OF ELECTRIC MOTOR AGAINST INJURIES Russian patent published in 1994 - IPC

FIELD: electrical engineering. SUBSTANCE: device for complex protection of electric motor against injuries has unit protection against delayed start, unit of protection of phase break, display unit, voltage divider, reference voltage correction unit including elements of smooth adjustment of reference voltage and of stepped switching of reference voltage calibrated in shares of rated current of electric motor. This makes it possible to simplify adjustment of relay to current of particular motor. Adjustment is run as follows: coarse adjustment is carried out by selection of division ratio of voltage divider in compliance with name plate of electric motor. Then electric motor is started and current is measured in phase of it, its relation to rated value is determined in shares and switch of stepped adjustment is set into position corresponding to given measurement. Then one strives for illumination of light emitting diode OVERLOAD with the aid of element of smooth adjustment of reference voltage, i.e. fine adjustment to particular value of current of electric motor is performed determined in shares of nominal value. Switch of stepped change of setting is put into various positions, i.e. value of overload of 100 or 110% is set. EFFECT: enhanced safety of operation of electric motor. 3 cl, 2 dwg