Install a protection circuit for the circuit breaker trip coil

æ³  æ³  è¡® 3 3 3 æ²³ æ²³ æ²³ æ²³ æ²³ æ²³ 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 First, it plays a decisive role in the safe operation of the power system. As a kind of instantaneous working element, the opening coil is often charged for a long time in the operation due to the opening mechanism, auxiliary contact or control circuit, etc., burning the opening coil, especially the frequently operated circuit breaker is more likely to occur, to the grid The safe and stable operation has a very negative impact. A protection circuit is added to the opening coil to prevent the opening coil from being burnt due to long-term charging.

1 The working principle is the schematic diagram of the opening coil protection circuit (the installation part is in the dotted line). When the circuit breaker is in the closing position, the 13 and 16 contacts of the control switch KK are turned on, the circuit breaker auxiliary contact DL is closed, and the red light HD is lit. At this time, a small current (about 0.1 A) flows through the opening coil TQ. Not enough to make TQ action. Since the voltage at both ends of the TQ is low (<10V), the time relay KT will not operate, and the opening coil protection circuit does not work, and has no effect on the circuit. When the protection action is opened or the opening operation is performed, the power supply voltage is applied to the opening coil through the protection circuit or the KK 6 and 7 contacts, via the anti-jump relay TB, the circuit breaker auxiliary contact DL, and the normally closed contact KA3 of the intermediate relay KA. Both ends of the TQ, and the action is opened; at the same time, the opening coil protection circuit starts to work, and the power supply voltage applied to both ends of the TQ causes the time relay KT to start timing. In the range of KT's setting time (about l~2s), if the circuit breaker is normally opened (opening time is about 6.~12s), the auxiliary contact DL is reliably disconnected, then KT loses power, stops timing, and opens the coil. The protection circuit does not operate. On the contrary, once the opening coil is energized for a long time, such as the auxiliary contact DL can not be opened or the circuit breaker is broken, when the KT action setting time is reached, the time-delay normally open contact KT is closed, and the intermediate relay KA is energized and touched. Point KA, closed self-holding, contact KA2 closed, the power supply is added to the alarm L alarm, and the contact KA3 opens the trip circuit, thus avoiding the opening coil being burned. At the same time, KT loses power and the contact KT is disconnected. SB is the alarm release button, press SB, disconnect the KA self-holding circuit, KA is powered off, KA2 disconnects the alarm circuit and cancels the alarm.

2 component selection is l~10s, intermediate relay selects DZL>204, alarm selection Therefore, the trigger width of the TSF controller should include not only the half cycle of the entire thyristor conduction, but also the half cycle of the diode conduction. That is, the trigger mode of the TSF should be full trigger or the trigger width is greater than 3/4 cycles. . (a) is the filter current waveform when the harmonic content is large, and (b) is the trigger waveform corresponding to the line voltage.

2 Conclusion TSF compensates the reactive power of the system as the switching standard, instead of switching the filter banks according to the harmonic condition of the system, which has a certain influence on the filtering effect. However, the larger the load, the larger the harmonic current, and the number of input filter banks increases with the increase of the reactive load, and most of the harmonics can still be filtered out. TSF has been put into operation in the electrical workshop of Tianjin Xiali Automobile Manufacturing Plant. The load of the plant has a large harmonic current, and it has strong impact and low operating power factor. After TSF is put into operation, these problems are basically solved. It greatly improves the harmonic pollution status of its power supply system, and quickly tracks the load changes for reactive power compensation, which improves the power factor of the system operation. It can be seen that the TSF is very high. The practical value of engineering.

(Finish)

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