CN209462004U - An automatic protection device for disconnection of secondary circuit of current transformer - Google Patents

Abstract

The utility model relates to an automatic protection device for disconnection of a secondary circuit of a current transformer, which comprises a fast knife switch KDZ and a voltage type relay DYJ; The two ends of the tail are connected separately, and the two connection points are used as lead-out terminals and connected to the secondary side winding of the current transformer to be protected. The utility model can quickly short-circuit the secondary side of the current transformer when the secondary circuit of the current transformer is disconnected and high voltage is induced on the secondary side, so as to eliminate the high voltage induced by the secondary side of the current transformer and avoid secondary Circuit insulation breakdown.

Description

An automatic protection device for disconnection of secondary circuit of current transformer

technical field

The utility model relates to the field of automatic protection of current transformers, in particular to an automatic protection device for secondary circuit breakage of current transformers.

Background technique

The current transformer is widely used in the current measurement of the power system, and the secondary side is not allowed to open circuit when it is in normal operation. When the current transformer is operating normally and the secondary side is open, a high voltage will be induced on the secondary side. The induced high voltage will cause the insulation breakdown of the secondary circuit and even cause the secondary circuit to catch fire and burn, resulting in the expansion of power grid accidents and economic losses. At the same time, if the induced high voltage is not eliminated in time, it will also pose a great threat to operating personnel and maintenance personnel, and even cause personal injury or death.

Contents of the invention

In view of this, the purpose of this utility model is to provide an automatic protection device for the secondary circuit breakage of the current transformer, which can quickly switch the current transformer The secondary side of the transformer is short-circuited, eliminating the high voltage induced by the secondary side of the current transformer, and avoiding the insulation breakdown of the secondary circuit.

The utility model adopts the following schemes to realize: An automatic protection device for disconnection of the secondary circuit of a current transformer, including a fast knife switch KDZ and a voltage type relay DYJ; The head and tail ends of the DYJ coil are connected separately, and the two connection points are used as lead-out terminals and connected to the secondary side winding of the current transformer to be protected.

Further, it also includes an external DC control power supply KM, a circuit breaker DL position contact, and a closing and holding relay HBJ; wherein the opening and closing of the fast knife switch KDZ are controlled by a control loop, and the control loop is specifically: a voltage type relay The normally open contact DYJ1 of the coil DYJ, the normally open contact DL1 of the circuit breaker DL position, the coil of the closing holding relay HBJ and the closing coil KDZH of the fast knife switch KDZ are connected in series and then connected to the external DC control power supply, and the closing holding relay HBJ The normally open contact HBJ1 of the voltage relay coil DYJ is connected in parallel; the normally closed contact DL2 of the circuit breaker DL, the normally open contact KDZ1 of the fast knife switch KDZ and the opening coil KDZF of the fast knife switch KDZ are connected in series After connecting, it is also connected to the external DC control power supply.

Preferably, the automatic control principle of the current transformer secondary circuit disconnection automatic protection device is as follows:

a) When the interval operates normally, the circuit breaker DL is in the closing state and the secondary circuit of the current transformer is not disconnected, the voltage relay coil (DYJ) is in the de-energized state, and its normally open contact (DYJ1) is in the open state, DL1 is in the closed state. At this time, the closing holding relay (HBJ) and the fast knife switch closing coil (KDZH) cannot be powered, and the fast knife switch (KDZ) is in the opening state;

b) When the interval operates normally, the circuit breaker DL is in the closed state and the secondary circuit of the current transformer is disconnected, the secondary side of the current transformer induces high voltage so that the coil of the voltage relay (DYJ) is in the energized state, and its normal When the opening contact (DYJ1) is closed and DL1 is in the closed state, the closing holding relay (HBJ) and the fast knife switch closing coil (KDZH) are energized, so that the fast knife switch closes quickly and short-circuits the secondary side of the current transformer , to eliminate the high voltage induced by the secondary side. At the same time, after the closing holding relay (HBJ) is energized, its normally open contact (HBJ1) is closed. As long as the circuit breaker does not open, the fast knife switch closing coil (KDZH) is always in the energized state, which can ensure the fast knife switch Always in the closed state;

c) When the interval is operating normally, the circuit breaker DL is in the closed state and the secondary circuit of the current transformer is disconnected, and the quick knife switch (KDZ) is closed, the normally closed contact (DL2) of the circuit breaker is in the open state, and the quick knife switch (KDZ) is closed. The normally open contact (KDZ1) of the brake is in the closed state. When the circuit breaker is opened, the normally closed contact (DL2) of the circuit breaker is closed, so that the fast knife switch opening coil (KDZF) is energized, and the fast knife switch is opened, thereby breaking Open the protection circuit. When the fast knife switch is opened, its normally open contact (KDZ1) is opened to cut off the opening circuit.

Compared with the prior art, the utility model has the following beneficial effects: the current transformer secondary circuit disconnection automatic protection device of the utility model can protect the secondary circuit of the current transformer when the secondary circuit is disconnected and the secondary side induces high voltage. , Quickly short-circuit the secondary side of the current transformer, eliminate the high voltage induced by the secondary side of the current transformer, avoid the insulation breakdown of the secondary circuit and even cause the secondary circuit to catch fire, resulting in the expansion of power grid accidents and economic losses. At the same time, quickly eliminating the high voltage induced by the secondary side is also conducive to ensuring the personal safety of operation and maintenance personnel and maintenance personnel.

Description of drawings

Fig. 1 is a wiring diagram of the utility model embodiment.

Fig. 2 is a wiring diagram of the automatic protection device of the embodiment of the present invention.

Fig. 3 is a wiring diagram of the fast knife switch control circuit of the present invention.

Detailed ways

Below in conjunction with accompanying drawing and embodiment the utility model is described further.

As shown in Figure 1, the wiring diagram of primary equipment such as current transformers and circuit breakers is shown in Figure 1. As shown in Figure 2, a current transformer secondary circuit disconnection automatic protection device in this embodiment includes a fast knife switch KDZ and a voltage relay DYJ; the head and tail ends of the fast knife switch KDZ are connected to the voltage The head and tail ends of the DYJ coil of the type relay are connected respectively, and the two connection points are used as lead-out terminals and connected to the secondary side winding of the current transformer to be protected.

In this embodiment, it also includes an external DC control power supply KM, a circuit breaker DL position contact, and a closing and holding relay HBJ; the opening and closing of the fast knife switch KDZ are controlled by a control loop, as shown in Figure 3. The specific control circuit is: the normally open contact DYJ1 of the voltage relay coil DYJ, the normally open contact DL1 of the circuit breaker DL position, the coil of the closing holding relay HBJ, and the closing coil KDZH of the fast knife switch KDZ are connected in series and then connected to an external DC On the control power supply, the normally open contact HBJ1 of the closing holding relay HBJ is connected in parallel with the normally open contact DYJ1 of the voltage relay coil DYJ; the position of the circuit breaker DL is normally closed contact DL2, the position of the fast knife switch KDZ is normally open The opening coil KDZF of the knife switch KDZ is also connected to the external DC control power supply after being connected in series.

Preferably, the automatic control principle of the current transformer secondary circuit disconnection automatic protection device is as follows:

a) When the interval operates normally, the circuit breaker DL is in the closing state and the secondary circuit of the current transformer is not disconnected, the voltage relay coil (DYJ) is in the de-energized state, and its normally open contact (DYJ1) is in the open state, DL1 is in the closed state. At this time, the closing holding relay (HBJ) and the fast knife switch closing coil (KDZH) cannot be powered, and the fast knife switch (KDZ) is in the opening state;

b) When the interval operates normally, the circuit breaker DL is in the closed state and the secondary circuit of the current transformer is disconnected, the secondary side of the current transformer induces high voltage so that the coil of the voltage relay (DYJ) is in the energized state, and its normal When the opening contact (DYJ1) is closed and DL1 is in the closed state, the closing holding relay (HBJ) and the fast knife switch closing coil (KDZH) are energized, so that the fast knife switch closes quickly and short-circuits the secondary side of the current transformer , to eliminate the high voltage induced by the secondary side. At the same time, after the closing holding relay (HBJ) is energized, its normally open contact (HBJ1) is closed. As long as the circuit breaker does not open, the fast knife switch closing coil (KDZH) is always in the energized state, which can ensure the fast knife switch Always in the closed state;

c) When the interval is operating normally, the circuit breaker DL is in the closed state and the secondary circuit of the current transformer is disconnected, and the quick knife switch (KDZ) is closed, the normally closed contact (DL2) of the circuit breaker is in the open state, and the quick knife switch (KDZ) is closed. The normally open contact (KDZ1) of the brake is in the closed state. When the circuit breaker is opened, the normally closed contact (DL2) of the circuit breaker is closed, so that the fast knife switch opening coil (KDZF) is energized, and the fast knife switch is opened, thereby breaking Open the protection circuit. When the fast knife switch is opened, its normally open contact (KDZ1) is opened to cut off the opening circuit.

It is worth mentioning that what the utility model protects is the hardware structure, and the control method does not require protection. The above is only a preferred implementation in the embodiment of the present invention. But, the utility model is not limited to above-mentioned embodiment, all changes and modifications done according to the utility model scheme, when the functional effect produced does not exceed the scope of the scheme, all belong to the protection scope of the utility model.

Claims (2)

1. The automatic safety device 1. a kind of secondary loop of mutual inductor breaks, it is characterised in that: including quick disconnecting link KDZ, voltage Type relay DYJ；The both ends end to end of the quick disconnecting link KDZ and the both ends end to end of the voltage-type relay DYJ coil are distinguished Connection, two tie point are connected in the secondary side winding of protected current transformer as leading-out terminal.
2. The automatic safety device 2. a kind of secondary loop of mutual inductor according to claim 1 breaks, it is characterised in that: also Including external DC control supply KM, breaker DL position contact and combined floodgate guard relay HBJ；Wherein quick disconnecting link KDZ Separating brake and close a floodgate by a control loop control, the control loop specifically: the normal opened contact of voltage-type relay coil DYJ The closing coil of DYJ1, the position breaker DL normal opened contact DL1, the coil of combined floodgate guard relay HBJ and quick disconnecting link KDZ KDZH concatenation is followed by external DC control supply, the normal opened contact HBJ1 and voltage-type relay of combined floodgate guard relay HBJ The normal opened contact DYJ1 of device coil DYJ simultaneously connects；The position normally closed contact DL2 of breaker DL, quick disconnecting link KDZ position normally opened connect It is equally connected on external DC control supply after the opening coil KDZF of point KDZ1 and quick disconnecting link KDZ concatenation.