DEVICE FOR CHECKING DC TRACTION MOTOR SELECTOR SWITCH THYRISTORS Russian patent published in 1997 - IPC

FIELD: electrified transport; starting resistor step checking device; short circuit protection of traction motor. SUBSTANCE: device has ac source, loading resistor, two light indicators, control relay, instrument current transformer, reference voltage source and line contactor controlled by master controller. Primary winding of instrument current transformer is connected through loading resistor and interlocking contact to one of outputs of ac source, and secondary winding is connected to circuit of power drive connecting cathode bus of thyristors of starting resistor step selector switch with end of last step of this resistor. Outputs of loading resistor are connected to one of inputs of compactor unit, other input of which is connected with output of reference voltage source. Output of comparator unit is connected to control relay supply winding. One contact of relay is placed in circuit between master controller and winding of line contactor, and other contact is placed in light indicator supply circuit. Power contact of line contactor is placed in series with traction motor circuit. EFFECT: improved short circuit protection of electric motor in case of breakdown of thyristors of starting resistor step selector switch. 1 dwg