RU95102880A - Device to protect dc traction circuit in case of damaged insulation of supports non grounded through rails - Google Patents

Abstract

FIELD: electric traction vehicles; DC circuit fault protection. SUBSTANCE: in case of break-down of one of insulators 21 high voltage of contact system 22 passes through valve element 4 to additional wire 3 and further on through barring element 2 to current sensor 1. Additional valve element 8 will save voltage source 6 from damage. Other valve elements 4 will prevent voltage shunting in additional wire 3 by internal resistance of other supports 20. In this case voltage across current sensor 1 will be higher than voltage across second resistor 10, but lower than voltage across third resistor 11. This will cause appearance of signals at outputs of first and second comparators, 13 and 14, respectively, and no signal across output of third comparator 15 and integrating network 16. Such combination of signals at outputs of second comparator 14 and integrating network 16 makes 2 AND gate 17 operate. Inverting input of gate 17 is connected with output of integrating network 16. Output signal from 2 AND gate 17 passes to quick-acting circuit breaker 5 and indicating device 18. Contact wire 22 is disconnected from supply feeder of traction substation 23. EFFECT: enhanced reliability of protection. 2 cl, 1 dwg

Claims (1)

In the event of a breakdown of one of the insulators 21, the high voltage of the contact network 22 through the valve element 4 will enter the additional wire 3 and then through the blocking element 2 to the current sensor 1. The additional valve element 8 will protect the voltage source 6 from damage. The remaining valve elements 4 will prevent voltage shunting in the additional wire 3 by the internal resistance of the other supports 20. In this case, the voltage on the current sensor 1 will be higher than the voltage on the second resistor 10, but lower than the voltage on the third resistor 11. This will lead to the appearance of signals at the outputs of the first 13 and the second 14 comparators and the absence of a signal at the output of the third comparator 15 and the integrating chain 16. This combination of signals at the outputs of the second comparator 14 and the integrating chain 16 will cause the element 2I-coagulant 17, inverse input connected to the output of integrating circuit 16. The output 2I element 17 enters the high-speed circuit breaker 5 and the display device 18. The trolley wire are disconnected from the power feeder 22, a traction network substation 23.