CN110716075A - A current transformer array switching circuit and control method - Google Patents

Abstract

The invention belongs to the electrical technology field of current transformers, and relates to a current transformer array switching circuit and method. The present invention includes a plurality of current mutual inductance CT switching circuits. The current mutual inductance CT switching circuit includes a first end S1 of a current transformer, a second end S2 of the current transformer, a normally closed switch K1, a normally open switch K2 and a detection channel C1, so The first end S1 of the current transformer, the second end S2 of the current transformer and the normally closed switch K1 are connected in series to form a loop, and one end of the normally open switch K2 is connected between the first end S1 of the current transformer and the normally closed switch K1. During this time, the other end of the normally open switch K2 is connected to the detection channel C1. On the current transformer array, through the combination of electrical switches, safe and reliable switching of the transformer array can be realized, in addition, the hardware detection channel can be greatly reduced, the cost is reduced, and the hardware utilization efficiency is improved.

Description

A current transformer array switching circuit and control method

technical field

The invention belongs to the electrical technology field of current transformers, and relates to a current transformer array switching circuit and a control method.

Background technique

At present, in the field of medium and high voltage electrical, there are two key points in the electrical design of current transformers: one is to ensure the reliable grounding of the secondary side, the purpose is to protect the safety of the equipment and personnel on the secondary side; the second is to ensure that the secondary side cannot be opened, the purpose It is to prevent high-voltage discharge from the open circuit of the secondary side. When the secondary side of the current transformer is open, thousands of volts will be generated secondary. Personnel are electrocuted, life-threatening. Therefore, under normal circumstances, the secondary side of the current transformer cannot be switched on and off, because the switching process inevitably produces an instantaneous open circuit.

In the prior art, there is no effective solution for the switching of current transformers. This means that there are as many current transformers as there are detection channels in the corresponding number. When there are too many current transformers, the number of hardware detection channels may be insufficient. In this case, a certain device needs to be used to switch the current transformers in turn so as to share fewer detection channels.

SUMMARY OF THE INVENTION

In order to solve the problems in the prior art, even if the secondary side of the current transformer can be switched safely and reduce the number of hardware detection channels, the present invention provides a current transformer array switching circuit and control method.

In order to achieve the above object, the technical solution adopted in the present invention is: a current transformer array switching circuit, which is characterized in that it includes a plurality of current transformer CT switching circuits, and the current transformer CT switching circuit includes the first end of the current transformer. S1, the second end S2 of the current transformer, the normally closed switch K1, the normally open switch K2 and the detection channel C1, the first end S1 of the current transformer and the second end S2 of the current transformer are connected in series with the normally closed switch K1 to form a loop, One end of the normally open switch K2 is connected between the first end S1 of the current transformer and the normally closed switch K1, and the other end of the normally open switch K2 is connected to the detection channel C1. The second end S2 of the current transformer is grounded, and the detection channel C1 is grounded.

The n current mutual inductance CT switching circuits are connected in parallel with K _2n through the normally open switch K2 to form a single-phase current transformer array, and the single-phase current transformer array is connected to a detection channel C1.

Three of the single-phase current transformer arrays form a three-phase current transformer array.

A control method for a current transformer array switching circuit, applied to any one of the circuits of claims 1-3, characterized in that it comprises the following steps:

S1. When no current is detected, the normally closed switch K1 remains closed;

S2. When the current needs to be detected, the normally open switch K2 is closed first, after a period of time delay Δt, to ensure that S1 and the detection channel C1 are completely connected, and then the normally closed switch K1 is disconnected;

S2. When the detection channel needs to be disconnected after the detection, first reset the normally closed switch K1, delay for a period of time Δt to ensure that S1 and S2 are completely short-circuited, and then reset the normally open switch K2.

In the single-phase current transformer array, n of the current mutual inductance CT switching circuits are switched in turn, and only one CT can be connected to the detection channel C1 at a time. The switching steps of each current mutual inductance CT switching circuit are the same as those described in the above method. .

Each single-phase current transformer array in the three-phase current transformer array is individually controllable.

Beneficial effects: The present invention provides a current transformer array switching circuit and a control method, which can make the secondary side of the current transformer connect or disconnect the detection channel safely and reliably. This method is applied to the current transformer array, and through the combination of electrical switches, the safe and reliable switching of the transformer array can be realized. Using this method, the hardware detection channel can be greatly reduced, the cost is reduced, and the hardware utilization efficiency is improved.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings required in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some of the present invention. In the embodiments, for those of ordinary skill in the art, other drawings can also be obtained according to these drawings without any creative effort.

Fig. 1 is a current transformer switching method diagram of the present invention;

Fig. 2 is the switching logic diagram of the current transformer of the present invention;

Fig. 3 is a single-phase current transformer array diagram of the present invention;

FIG. 4 is an array diagram of a three-phase current transformer of the present invention.

Detailed ways

In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific embodiments, structures, features and effects of the application according to the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments. .

Example 1

A current transformer array switching circuit is characterized in that it includes a plurality of current transformer CT switching circuits, as shown in FIG. The normally closed switch K1, the normally open switch K2 and the detection channel C1, the first end S1 of the current transformer, the second end S2 of the current transformer are connected in series with the normally closed switch K1 to form a loop, and one end of the normally open switch K2 is connected to the Between the first end S1 of the current transformer and the normally closed switch K1, the other end of the normally open switch K2 is connected to the detection channel C1, the second end S2 of the current transformer is grounded, and the detection channel C1 is grounded.

As shown in Figure 2, a control method of a current transformer array switching circuit includes the following steps:

S1. When no current is detected, the normally closed switch K1 remains closed;

S2. When the current needs to be detected, the normally open switch K2 is closed first, after a period of time delay Δt, to ensure that S1 and the detection channel C1 are completely connected, and then the normally closed switch K1 is disconnected;

S2. When the detection channel needs to be disconnected after the detection, first reset the normally closed switch K1, delay for a period of time Δt to ensure that S1 and S2 are completely short-circuited, and then reset the normally open switch K2.

Through the implementation of the above circuit and method, the secondary side of the current transformer can be connected to or disconnected from the detection channel safely and reliably, so as to solve the problem of potential safety hazards existing in the secondary side of the current transformer in the prior art, and ensure the power-on equipment and maintenance personnel. security.

Embodiment 2

As shown in FIG. 3 , the n current mutual inductance CT switching circuits are switched in turn, and only one CT can be connected to the detection channel C1 at a time. The switching steps of each current mutual inductance CT switching circuit are the same as those described in claim 4 .

The single mutual inductor array shares one detection channel, and each current mutual inductor CT switching circuit can realize the round sequence switching in the single mutual inductor array through the normally closed switch K1 and the normally open switch K2 according to the operation method in the first embodiment. The circuit and method greatly reduce hardware detection channels, and are safe and reliable. The closing or opening of the electrical switch can be controlled by a programmable device such as a PLC, an industrial computer, etc., which makes the control more convenient.

Embodiment 3

Three of the single-phase current transformer arrays form a three-phase current transformer array.

Each single-phase current transformer array in the three-phase current transformer array is individually controllable.

Figure 4 shows the switching principle of the three-phase current transformer array. The signal detection of the three-phase current transformer array requires three detection channels C1-C2-C3, corresponding to the three-phase A-B-C respectively. For each phase, the current transformer switching and detection principles are exactly the same as in Figure 3.

The difference is that in order to ensure that the three-phase ABC of the same group is detected and disconnected at the same time, KA1-KB1-KC1 is triggered by the same control signal to achieve linkage effect, and KA2-KB2-KC2 is also triggered by the same control signal. , and so on. That is to say, the three switches in each horizontal direction in FIG. 4 are triggered synchronously, which ensures the simultaneity of three-phase detection.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (6)

1. A current transformer array switching circuit, characterized in that it comprises a plurality of current transformer CT switching circuits, and the current transformer CT switching circuit comprises a current transformer first end S1, a current transformer second end S2, a normally closed The switch K1, the normally open switch K2 and the detection channel C1, the first end S1 of the current transformer, the second end S2 of the current transformer are connected in series with the normally closed switch K1 to form a loop, and one end of the normally open switch K2 is connected to the Between the first end S1 of the current transformer and the normally closed switch K1, the other end of the normally open switch K2 is connected to the detection channel C1, the second end S2 of the current transformer is grounded, and the detection channel C1 is grounded. 2. A current transformer array switching circuit as claimed in claim 1, characterized in that, a single-phase current transformer array is formed by connecting n of the current transformer CT switching circuits in parallel with the normally open switches K2 and _K2n , so the The single-phase current transformer array is connected to a detection channel C1. 3 . The current transformer array switching circuit according to claim 1 , wherein three single-phase current transformer arrays form a three-phase current transformer array. 4 . 4. A control method of a current transformer array switching circuit, applied to any one of the circuits of claims 1-3, characterized in that, comprising the following steps: S1. When no current is detected, the normally closed switch K1 remains closed; S2. When the current needs to be detected, the normally open switch K2 is closed first, after a period of delay Δt, to ensure that S1 and the detection channel C1 are completely connected, and then the normally closed switch K1 is disconnected; S2. When the detection channel needs to be disconnected after the detection, first reset the normally closed switch K1, delay a period of time Δt to ensure that S1 and S2 are completely short-circuited, and then reset the normally open switch K2. 5. A method for controlling a current transformer array switching circuit, applied to any one of the circuits of claims 1-3, wherein in the single-phase current transformer array, n of the current transformer CT switching circuits In alternate switching, only one CT can be connected to the detection channel C1 at a time, and the switching steps of each current mutual inductance CT switching circuit are the same as those described in claim 4 . 6. A control method for a current transformer array switching circuit, which is applied to any one of the circuits of claims 1-3, wherein each single-phase current transformer array in the three-phase current transformer array can be individual control.

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