CN103809146A - Test method of main transformer CT (Current Transformer) - Google Patents

Abstract

A test method for a current transformer of a main transformer, the steps of which are as follows: under the condition that the current transformer carries all the secondary loop currents, connect the three phases of the high voltage side, the medium voltage side and the low voltage side of the main transformer with lead wires, and cross the transformer , close the isolating switch on one side and the circuit breaker and grounding isolating switch on the other two sides, and add three-phase current through the three-phase current generator on the side of the current transformer on the side of the unsuitable circuit breaker and grounding isolating switch, so that the current flows through the three phases of the transformer The current transformer on the side of the transformer simulates the load current on the three sides during normal operation of the transformer; the current value, phase and difference current of each side are detected at the differential protection device of the main transformer. If the difference current = 0, each current transformer becomes The ratio, polarity and differential circuits are wired correctly. The invention can simultaneously check the polarity of each current transformer of the main transformer, the transformation ratio and the correctness of the differential circuit connection, improves the work efficiency and inspection quality, and ensures that the electrical equipment can be reliably put into operation.

Description

Test method for main transformer current transformer

technical field

The invention relates to a test method for a main transformer current transformer.

Background technique

The substation is an important hub of the high-voltage power grid, and the current transformer is an essential primary equipment in the substation. The conventional current transformer converts the primary current with a large value into a secondary current with a small value through the principle of electromagnetic induction, which is used to control Primary equipment for protection, measurement, metering, etc. In the process of operation, for the safety of the equipment, it is necessary to prevent the secondary open circuit of the current transformer, and the transformation ratio, 10% error, and polarity of the current transformer play an important role in the correct realization of functions such as protection, protection, measurement, and metering. The primary current inspection of the main transformer current transformer is mainly to check the polarity of the current transformer, the transformation ratio and the integrity of the secondary circuit to prevent the secondary circuit from being open. The existing problem is that the polarity, Correctness of transformation ratio and loop wiring.

Contents of the invention

The present invention provides a test method for the current transformer of the main transformer, which solves the problem that the load phase test cannot be carried out due to the too small secondary current of the light-load equipment after power transmission, so that it cannot be put into operation in time. the

The test method of main transformer current transformer that the present invention relates to, its steps are as follows:

1. When the current transformer carries all the secondary circuit current, use lead wires to connect the three phases of the high voltage side, medium voltage side and low voltage side of the main transformer respectively, cross the transformer, close the isolating switch on one side and the open circuit on the other two sides The three-phase current generator is used to add three-phase current to the side of the current transformer on the side of the unsuitable circuit breaker and grounding isolating switch, so that the current flows through the current transformers on the three sides of the transformer, and the three sides are simulated when the transformer is in normal operation. The load current condition;

2. The current value, phase and differential current on each side are detected at the differential protection device of the main transformer. If the differential current = 0, the transformation ratio, polarity and differential circuit wiring of each current transformer are correct; if the differential current ≠ 0 , the transformation ratio, polarity and differential circuit wiring of each current transformer are incorrect.

The beneficial effects of the present invention are: the polarity of the secondary circuits of each current transformer of the main transformer, the transformation ratio and the correctness of the connection of the secondary circuits can be checked at the same time, the work efficiency and inspection quality are improved, and the current transformers and differential circuits can be found early It also solved the problems that the main transformer differential, equipment protection, metering, etc. could not be put into operation in time because the load of some equipment was too small when it was put into operation, and the phase problems of some equipment at the light load side ensured that the electrical equipment was put into operation reliably.

Description of drawings

Fig. 1 is a wiring diagram of the present invention.

Detailed ways

As shown in the figure, the steps of the present invention are as follows:

1. When the current transformer carries all the secondary circuit current, use lead wires to connect the three phases of the high voltage side, medium voltage side and low voltage side of the main transformer respectively, cross the transformer, close the disconnect switch on the high voltage side and the open circuit on the other two sides On the high voltage side current transformer side of unsuitable circuit breaker and grounding isolating switch, the three-phase current is added through the three-phase current generator, so that the current flows through the current transformers on the three sides of the transformer, and the three-phase current is simulated when the transformer is in normal operation. side load current condition;

2. The current value, phase and differential current on each side are detected at the differential protection device of the main transformer. If the differential current = 0, the transformation ratio, polarity and differential circuit wiring of each current transformer are correct; if the differential current ≠ 0 , the transformation ratio, polarity and differential circuit wiring of each current transformer are incorrect.

It is also possible to add three-phase current through a three-phase current generator on the medium-voltage side or low-voltage side, and the method is the same as above.

Claims (1)

1. the test method of main transformer current transformer, is characterized in that step is as follows:

(1), in the whole secondary loop current situations of current transformer band, with going between, main transformer high-pressure side, medium voltage side and low-pressure side three-phase are connected respectively, stride across transformer, isolating switch, the earthing isolator of a side disconnector and all the other both sides close, not conforming to isolating switch, earthing isolator one side current transformer side adds three-phase current by three-phase current generator, make electric current flow through the current transformer of transformer three sides, the load current situation of three sides when analogue transformer normally moves;

(2), detect each side current values, phase place and spill current at main transformer differential protective device place,, as spill current=0, each current transformer ratio, polarity and differential circuit wiring are correct; As spill current ≠ 0, each current transformer ratio, polarity and differential circuit wiring are incorrect.

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