Anti jump principle of the hottest high voltage el

High voltage electrical anti jump principle

35kv and above circuit breakers often use electrical anti jump. This anti tripping relay has two coils, one is the current coil for starting, which is connected in the tripping circuit; The other is the voltage coil for self holding, which is connected to the closing circuit through its normally open contact (tbj1)

during the closing process, if a permanent fault is encountered, the protection outlet relay contact BCJ is closed, the circuit breaker trips, and the anti tripping relay TBJ is started. If the control switch handle (closing button) is not reset or its contact is stuck, and the closing contact of the automatic closing device is stuck (not separated), because the contact tbj1 of the anti tripping relay has been closed, the voltage coil of TBJ is charged and plays the role of self holding. In addition, the contact tbj2 has been disconnected, which can prevent the closing coil HQ from conducting again, and also prevent the circuit breaker from jumping

the function of contact tbj3 (together with the contact of BCJ) is to prevent the contact of protection outlet relay BCJ from being burnt out. Because during automatic tripping, the contact of BCJ may be disconnected before the auxiliary contact QF2 (the normally open auxiliary contact of the circuit breaker in series before the tripping coil TQ), so that it is burnt out by the arc. Since tbj3 is connected in parallel with it, even if the contact of BCJ is broken first, it will not be burned out, and there is a tripping outlet

1 circuit analysis of jump locking circuit

Electrical jump locking circuit is usually realized by jump locking relay. Figure 1 is the wiring diagram of jump locking circuit applicable to the circuit breaker with one tripping coil. The jump locking relay TBJ has a current starting coil tbj/i, a voltage holding coil tbj/u, two pairs of dynamic making contacts tbj1, TBJ 4 and two pairs of dynamic breaking contacts TBJ 2, tbj3, tbj/i connected to the tripping coil circuit of the circuit breaker, tbj/u connected to the closing circuit of the circuit breaker, tbj1 used for current self holding, tbj2, tbj3 connected in series into the closing circuit after being connected in parallel

when the tripping relay TJ acts to start tripping, tbj/i is excited, TBJ acts, tbj1 is closed, and the tripping command is maintained until the circuit breaker is disconnected. At the same time, tbj2 and tbj3 open the closing circuit, tbj4 is closed, and the voltage self holding circuit of TBJ is ready. If the manual closing relay contact SHJ or automatic reclosing contact zhj is closed before the circuit breaker is disconnected, that is, before the TBJ does not return, the TBJ will be self maintained by the closed TBJ 4 and SHJ or zhj, that is, tbj2 and TBJ 3 will continue to be in the disconnected state to ensure that the circuit breaker will not be closed and achieve the purpose of jump locking

2 technical requirements for jump lock relay

2 1 current starting value

according to the anti accident measures of the Ministry of electric power industry in 1984 and the regulations of the secondary circuit design specification of power system, the current starting value of the jump locking relay should match the tripping current of the circuit breaker, and its current starting value should not be greater than 50% of the tripping current of the circuit breaker, that is, the current of the tripping circuit during tripping should be greater than 2 times of the TBJ starting current, so as to ensure that the reliability factor of the TBJ current is greater than 2

2. 2 voltage drop of current coil

according to the above provisions, the voltage drop of the current coil of the jump locking relay should be less than 5% of the rated voltage of the operating circuit

2. 3. Voltage action value

according to the regulations, the voltage action value of the jump locking relay should not be greater than 70% of the rated DC voltage of the operating circuit, so as to ensure the reliable action of TBJ when the operating DC power supply voltage fluctuates within the specified range; At the same time, the TBJ voltage action value should not be less than 50% of the rated direct current voltage of the operating circuit, so as to ensure that the TBJ will not misoperate when the operating DC power circuit is grounded

2. 4 contact performance

the contact performance of TBJ should be the same as that of the outlet intermediate relay in the relay protection device. According to the power industry standard [1], the contact performance of the outlet intermediate relay in the relay protection device should meet the following requirements: return characteristics, 10% of the rated value of the return value (for dry spring relay, 70% of the rated value of the return value is required); Closed capacity, DC circuit 220 V, 5 A; Mechanical life, 105 actions without load; Contact resistance, when measured with a milliohmmeter, 0 1. 0 when measured with a digital multimeter 5 when measured by current voltage method, 0 1 。

2. 5. Insulation performance

a. when the same group of contacts is disconnected, it can withstand power frequency voltage of 1000 V for 1 min

b. between conductive parts without electrical connection, it can withstand power frequency voltage of 2000 V for 1 min

c. between all conductive parts and mounting frames, it can withstand power frequency 2000 V voltage for 1 min

3 composition of jump lock relay starting circuit

3 1 change the parameters of the relay current coil

generally, the current type relay with current type action coil is selected as the jump locking relay TBJ, and the current action value of its current coil is selected according to the tripping current of the circuit breaker to ensure the action sensitivity of the relay. The relay current action value designed for this requirement is specified as 30% ～ 50% of the nominal rated value. As long as the relay current is selected to be consistent with the circuit breaker current, the requirement of relay sensitivity can be met

the advantage of selecting current type relay as jump locking relay TBJ is that the jump locking circuit wiring is simple, and the current coil of TBJ can be monitored through the closing position relay hwj. In the process of operation, if TBJ is disconnected, hwj will send an abnormal alarm signal for timely processing. Its disadvantage is that when the tripping current of the circuit breaker changes, the relay with corresponding current specification must be replaced, which is more troublesome

3. 2 relay coil and parallel branch

in order to reduce the workload of replacing the TBJ parameters of jump lock relay caused by the change of circuit breaker parameters, relevant technicians and manufacturing units have been looking for a method suitable for circuit breakers of various specifications. Among them, the method of using voltage type relay to shunt the voltage coil of the relay in parallel

branch is gradually being recognized by people. Its parallel branch can be composed of resistance, diode or voltage stabilizing tube circuit respectively. The following describes the current starting circuit of jump lock relay composed of voltage type relay and resistance, diode 4.2.8.1 heating furnace 1) adopts split heating furnace and voltage stabilizing tube parallel branch (as shown in Figure 2 (a) (pull the black knob b) (c))

3. 2.1 it is composed of relay voltage coil and resistance parallel branch

as shown in Figure 2 (a), the current starting value of relay J/I is 0 07～0. 12 A, coil resistance is 10. The parallel resistors are generally divided into 4 groups, and one or several resistors can be connected with the connecting piece to adjust the shunt size, so as to change the action value of the relay and realize the matching with the tripping current of the circuit breaker. When using this circuit, attention should be paid to preventing the resistance from breaking. It is advisable to select a metal oxide film resistor with a power of 8 ~ 10 W, which has high reliability

3.2.2 it is composed of relay voltage coil and diode parallel branch, as shown in Figure 2 (b), and the current starting value of relay J/I is 0 07～0. 12 has a very broad application prospect a, and the coil resistance is 10. The four diodes in parallel are connected in series and then connected in parallel at both ends of the relay coil, and the midpoint of the two strings is connected. This wiring can ensure that when one of the diodes is open circuit, the circuit works normally and improve the reliability of the circuit. At the same time, the two branches can share large current to prevent diode damage caused by excessive current

after testing, according to this wiring, the passing current is 0 At 25 ~ 10 A, the voltage at both ends is 1 2～2. 3 V, the current in the relay starting coil is 0 12～0. 23 A, which can not only meet the requirement that the voltage drop is less than 5% of the rated voltage, but also ensure the action sensitivity of the relay

3.2.3 it is composed of relay voltage coil and parallel branch of regulator tube

as shown in Figure 2 (c), the current starting value of relay j/i is 0 07～0. 12 A, coil resistance is 10. The rated regulated voltage of VS1 and VS2 is 1 5 V, rated current is 5 a. Two regulators in parallel can improve the reliability of the circuit. The test shows that the circuit can meet the requirements that the voltage drop is less than 5% of the rated voltage and ensure the action sensitivity of the relay

the deficiency of the current starting circuit of the jump locking relay composed of relay coil and parallel branch is that the parallel branch is added at the end of relay coil 2, so the relay coil cannot be monitored. If the relay coil is disconnected, incorrect action will occur

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conclusion

the circuit breaker jump locking device composed of electrical circuits is still widely used. The way of changing relay current coil parameters is the main way of application at present because of its simple wiring and easy monitoring; The mode of jump lock relay current starting circuit

composed of relay coil and parallel branch is more popular with manufacturers and operators because it is easy to change parameters. However, due to the complexity of the circuit and the inability to monitor the relay coil, it still needs to further accumulate experience and use it carefully

References:

[1] dl/t 478o2001 General technical conditions for static relay protection and safety automatic devices [S]