Power transformer water cooler control circuit

Abstract

A control circuit for a water cooler of a power transformer. When the transformer is operating normally, it is easy to misreport a "cooler full stop" signal, and it is easy to misissue a "cooler full stop trip" signal, causing the transformer protection device to mistakenly trip the normally operating transformer. The present invention comprises: the control circuit comprises a transformer cooler automatic input circuit (19) connected in parallel in the main circuit (23), a transformer cooler non-operation circuit (20), a transformer cooler water flow fault circuit (21) and a transformer cooler fault circuit (22). The present invention is used for controlling a water cooler of a power transformer.

Description

Technical field:

[0002] The invention relates to a control loop of a water cooler of a power transformer. Background technology:

[0004] There are some problems with the control logic of traditional power transformer water coolers. When the transformer is operating normally, it is easy to falsely report the "cooler full stop" signal and falsely issue the "cooler full stop trip" signal, causing the transformer protection device to falsely trip the normally operating transformer. The main problems are as follows:

[0005] 1. The control contacts of the automatic cooler input circuit are taken from the closing position contacts of the circuit breaker on the high-voltage side of the transformer. When the DC power supply disappears or the DC circuit breaker trips, the control system considers that the transformer has exited operation, and will automatically stop the operation of a group of coolers.

[0006] 2. After the transformer stops operating, its cooler will still issue a "cooler full stop trip" signal.

[0007] 3. When the unit and transformer share the cooling water system, the cooling water will be interrupted after the unit is shut down, and the transformer cooler will issue "cooler full stop" and "cooler full stop trip" signals.

[0008] 4. The judgment logic of the cooler fault signal does not take into account the transformer oil temperature signal of 55 degrees. After the unit is shut down, the cooling water is interrupted, which will cause the "cooler fault" and "cooler complete stop" signals to be falsely reported. Summary of the invention:

[0010] The purpose of the present invention is to solve the problems existing in the control logic of the current power transformer water cooler and to provide a control loop for the power transformer water cooler.

[0011] The above purpose is achieved through the following technical solutions:

[0012] A power transformer water cooler control circuit, the control circuit comprising a transformer cooler automatic input circuit, a transformer cooler non-operation circuit, a transformer cooler water flow fault circuit and a transformer cooler fault circuit connected in parallel in a main circuit;

[0013] The transformer cooler automatic input circuit includes a first relay coil and a second relay coil, wherein the first relay coil is connected in series with the open position of the transformer high-voltage side circuit breaker, and the second relay coil is connected in series with the normally open contact of the first relay;

[0014] The transformer cooler non-operation circuit includes a first time delay relay coil and a third relay coil, wherein the first time delay relay coil is connected in series with the normally closed contact of the cooler non-operation switch, and the third relay coil is connected in series with the normally open delayed closing contact of the first time delay relay;

[0015] The transformer cooler water flow fault circuit includes a water flow fault detection circuit, and the water flow fault detection circuit is connected in series with the transformer oil temperature switch;

[0016] The transformer cooler fault circuit comprises a cooler fault relay coil, and the cooler fault relay coil is connected in series with a fault detection circuit.

[0017] The power transformer water cooler control loop, the water flow fault detection circuit comprises a water flow fault relay coil and a water flow disappearance switch connected in series.

[0018] The power transformer water cooler control circuit, the fault detection circuit includes an oil pump overload switch, an oil flow fault switch, a leakage fault switch, a valve fault switch and a normally open contact of the water flow fault relay connected in parallel.

[0019] Beneficial effects:

[0020] 1. The present invention is provided with an automatic cooler input circuit for the transformer, and the control contacts of the automatic cooler input circuit are taken from the open position contacts of the high-voltage side circuit breaker of the transformer. When the transformer operates normally, the high-voltage side circuit breaker is in the closed position, and a group of coolers are automatically started to operate.

[0021] 2. The present invention sets a transformer cooler non-operation loop. When the transformer is put into operation and the 1#, 2# and 3# coolers are not operating, a delay of 10 seconds is given to send a cooler non-operation signal.

[0022] 3. The present invention sets a transformer cooler water flow fault circuit. When the cooler water flow disappears and the transformer oil temperature reaches 55 degrees, a cooler water flow fault signal is immediately issued.

[0023] 4. The present invention sets a transformer cooler fault circuit. When the cooler oil pump is overloaded, the cooler oil flow fails, the cooler leaks, the cooler valve fails, or the cooler water flow fails, the control system reports "cooler failure".

[0024] 5. The present invention can prevent control logic errors and disorders, and ensure that the control system does not mistakenly issue a "cooler full stop trip" signal, causing the normally operating transformer to mistakenly trip and exit operation. Description of the drawings:

[0026] Attached Figure 1 is a circuit diagram of the present invention;

[0027] Attached Figure 2 This is the circuit diagram of the transformer cooler automatic input circuit;

[0028] Attached Figure 3 It is the circuit diagram of the transformer cooler not running loop;

[0029] Attached Figure 4 It is the circuit diagram of the transformer cooler water flow fault circuit;

[0030] Attached Figure 5 It is the circuit diagram of the transformer cooler fault circuit;

[0031] In the figure: 1. DC power supply; 2. air switch; 3. first relay coil; 4. second relay coil; 5. cooler not running switch; 6. first delay relay coil; 7. third relay coil; 8. water flow fault relay coil; 9. fault detection circuit; 10. cooler fault relay coil; 11. transformer high voltage side circuit breaker opening position; 12. water flow disappearance switch; 13. transformer oil temperature switch; 14. water flow fault detection circuit; 15. oil pump overload switch; 16. oil flow fault switch; 17. leakage fault switch; 18. valve fault switch; 19. transformer cooler automatic input circuit; 20. transformer cooler not running circuit; 21. transformer cooler water flow fault circuit; 22. transformer cooler fault circuit; 23. main circuit. Specific implementation method:

[0033] Embodiment 1:

[0034] A power transformer water cooler control circuit, the control circuit includes a transformer cooler automatic input circuit 19, a transformer cooler non-operation circuit 20, a transformer cooler water flow fault circuit 21 and a transformer cooler fault circuit 22 connected in parallel in a main circuit 23, such as Figure 1-5 As shown, three transformer coolers are taken as an example;

[0035] The transformer cooler automatic input circuit includes a first relay coil 3 and a second relay coil 4, wherein the first relay coil is connected in series with the transformer high-voltage side circuit breaker opening position 11, and the second relay coil is connected in series with the normally open contact of the first relay;

[0036] Principle of the automatic start-up circuit of the transformer cooler: The control contact of the automatic start-up circuit of the cooler is taken from the open position contact DLF of the transformer high-voltage side circuit breaker. When the transformer is operating normally, its high-voltage side circuit breaker is in the closed position, the DLF contact is disconnected, the relay K1 loses power and releases, and the K2 relay is energized and energized to automatically start a group of coolers. When the DC power supply KM disappears, or the QF1 circuit breaker trips, the relay K1 remains in the de-energized release state, and the K2 relay remains in the energized energized state. The control system believes that the transformer is in operation, and thus a group of coolers will be kept in operation;

[0037] The transformer cooler non-operation circuit includes a first delay relay coil 6 and a third relay coil 7, wherein the first delay relay coil is connected in series with the normally closed contact of the cooler non-operation switch 5, and the third relay coil is connected in series with the normally open delayed closing contact of the first delay relay;

[0038] Transformer cooler non-operation loop principle: When the transformer is put into operation, and the 1#, 2#, and 3# coolers are not running, a delay of 10 seconds is issued, and a cooler non-operation signal is issued. This logic has taken into account whether the transformer has been put into operation, that is, when the transformer is out of operation, the control system will not issue a "cooler not running" signal, and thus will not issue a "cooler all stopped" signal;

[0039] The transformer cooler water flow fault circuit includes a water flow fault detection circuit 14, and the water flow fault detection circuit is connected in series with the transformer oil temperature switch 13;

[0040] Principle of transformer cooler water flow fault circuit: When the water flow of 1# cooler disappears and the transformer oil temperature reaches 55 degrees, the 1# cooler water flow fault signal will be issued immediately. The water flow fault logic of 2# and 3# coolers is the same as that of 1# cooler. Since the unit and the transformer share the cooling water system, when the cooling water is interrupted after the unit is shut down, as long as the transformer oil temperature does not reach 55 degrees, the three groups of coolers will not issue a "cooler water flow fault" signal, and the control system will not issue a "cooler full stop" signal;

[0041] The transformer cooler fault circuit includes a cooler fault relay coil, and the cooler fault relay coil 10 is connected in series with the fault detection circuit 9;

[0042] Transformer cooler fault circuit principle: When the 1# cooler oil pump is overloaded, the 1# cooler oil flow fails, the 1# cooler leaks, the 1# cooler valve fails, or the 1# cooler water flow fails, the "1# cooler fault" signal will be reported. The fault logic of 2# and 3# coolers is the same as that of 1#. This logic has taken into account the cooler water flow failure (not the disappearance of water flow). Since the unit and the transformer share the cooling water system, when the unit is shut down and the cooling water is interrupted, as long as the transformer oil temperature does not reach 55 degrees, the "cooler fault" signal will not be reported, and thus the "cooler full stop" signal will not be reported.

[0043] Embodiment 2:

[0044] According to the power transformer water cooler control circuit described in Example 1, the water flow fault detection circuit includes a water flow fault relay coil 8 and a water flow disappearance switch 12 connected in series.

[0045] Embodiment 3:

[0046] According to the power transformer water cooler control circuit described in Example 1 or 2, the fault detection circuit includes an oil pump overload switch 15, an oil flow fault switch 16, a leakage fault switch 17, a valve fault switch 18 and a normally open contact of the water flow fault relay connected in parallel.

Claims

1. A power transformer water cooler control circuit, characterized in that: The control circuit includes a transformer cooler automatic input circuit, a transformer cooler non-operation circuit, a transformer cooler water flow fault circuit and a transformer cooler fault circuit connected in parallel in the main circuit; The transformer cooler automatic input circuit includes a first relay coil and a second relay coil, wherein the first relay coil is connected in series with the open position of the transformer high-voltage side circuit breaker, and the second relay coil is connected in series with the normally open contact of the first relay; The transformer cooler non-operation circuit includes a first delay relay coil and a third relay coil, wherein the first delay relay coil is connected in series with the normally closed contact of the cooler non-operation switch, and the third relay coil is connected in series with the normally open delayed closing contact of the first delay relay; the delay time of the first delay relay is 10 seconds; The transformer cooler water flow fault circuit includes a water flow fault detection circuit, which is connected in series with the transformer oil temperature switch; when the transformer oil temperature reaches 55 degrees, a 1# cooler water flow fault signal is immediately issued; the transformer cooler fault circuit includes a cooler fault relay coil, which is connected in series with the fault detection circuit; the water flow fault detection circuit includes a water flow fault relay coil and a water flow disappearance switch connected in series; the fault detection circuit includes an oil pump overload switch, an oil flow fault switch, a leakage fault switch, a valve fault switch and a normally open contact of the water flow fault relay connected in parallel.

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