Zero-sequence current transformer working principle and scope of use - Database & Sql Blog Articles

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The zero-sequence current transformer has a wider range of applications. It not only adapts to electromagnetic relay protection, but also adapts to electronic and microcomputer protection devices. Users can operate according to the system's operation mode, neutral grounding or neutral point non-effective grounding. Use the corresponding zero-sequence current transformer.

The zero-sequence current transformer cooperates with the relay protection device and the signal when the power system generates the zero-sequence ground current, so that the device components operate to achieve protection or monitoring. DH-LJ series zero-sequence current transformer makes cable type, adopts ABS engineering plastic shell, resin is cast into full seal, good insulation performance and beautiful appearance. It has the characteristics of high sensitivity, good linearity, reliable operation and convenient installation. The performance of the device is better than the general zero-sequence current transformer. It has a wider range of applications. It not only adapts to electromagnetic relay protection, but also adapts to electronic and microcomputer protection devices. Users can effectively ground or neutral according to the operating mode of the system. For the difference of non-effective grounding, select the corresponding zero-sequence current transformer.

Principle: The basic principle of zero-sequence current protection is based on Kirchhoff's current law: the algebraic sum of the complex currents flowing into any node in the circuit is equal to zero. In the case of normal line and electrical equipment, the vector sum of the currents of the phases is equal to zero. Therefore, the secondary winding of the zero-sequence current transformer has no signal output, and the actuator does not operate. When the ground fault occurs, the vector sum of each phase current is not zero, the fault current causes magnetic flux to be generated in the toroidal core of the zero-sequence current transformer, and the secondary side induced voltage of the zero-sequence current transformer causes the actuator to act, driving The tripping device switches the power supply network to achieve the purpose of ground fault protection.

A current transformer can be installed on each of the three-phase lines, or the three-phase wires can pass through a zero-sequence current transformer together, or a zero-sequence current transformer can be installed on the neutral line N, and the three-phase current transformer can be used to detect the three-phase. Current vector and.

"Principle: The basic principle of zero-sequence current protection is based on Kirchhoff's current law: the algebraic sum of the complex currents flowing into any node in the circuit is equal to zero. In the case of normal line and electrical equipment, the vector sum of the phase currents is equal to zero. Therefore, the secondary winding of the zero-sequence current transformer has no signal output, and the actuator does not operate."

There is a mistake in this discussion!

1. I feel that you are talking about the current transformer in the RCD residual current leakage protector;

2. The current transformer measures the residual branch current, which is the sum of the currents through all the branches passing through it, and knows the remaining branch current that has not passed through it;

3, so call it the residual current transformer is more accurate;

1, zero sequence current generally refers to the zero line current, the current outside the phase line;

2, zero-sequence current transformer, is to measure the zero-sequence current, the transformer must be three phase lines, the working zero line does not pass the transformer;

3. If there are three phase lines passing through the transformer, and there is no zero line at the Y point of the device, that is, the zero line current is zero at this time, that is, the three-phase is unbalanced, and the zero-sequence current is also zero;

1. The current transformer in the RCD residual current leakage protector requires that all power lines (three phase lines L, working zero line N) within the protected range must pass through it;

2. When leakage occurs within the protected range, the leakage current is the remaining branch current that has not passed through it, and is detected and signals;

3. When there is leakage in the protected range, the leakage current is the remaining branch current that has not passed through it, and it is detected that this current is not zero-sequence current!!