DEVICE TO PROTECT AND TEST RESISTANCE OF INSULATION OF ELECTRIC APPARATUSES Russian patent published in 2002 - IPC

FIELD: electrical engineering. SUBSTANCE: invention deals with electrical sets in three-phase networks with solidly grounded neutral. Device includes generator of network with connected measurement circuit. Measurement circuit comes in the form of variable-induction pickup placed in series in circuit of protective grounding conductor and two comparators. One of its leads-out is inserted in series with variable resistor. Load resistor is linked with one lead to point of connection of mobile contact and free lead of variable resistor. Its other lead is connected to second lead-out of inductive pickup. Capacitor is connected in parallel with load resistor, its leads are connected to first input of first comparator and second input of second comparator, second input of first comparator and first input of second comparator, comparators outputs being coupled to delay unit whose output is linked to input of actuating element manufactured in the form of key amplifier. Resistive isolation is installed in collector circuit of key amplifier and its output is linked to electron contact acting on actuating element. With fall of insulation resistance electric apparatus is disconnected from A C network with indication of normal and emergency operation. EFFECT: simplified design and expanded functional potential of device. 1 cl, 2 dwg