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Method of variable ratio test for current transformers
- Jun 01, 2018 -

Current transformer is a special type of transformer used for converting current. Under normal working conditions, the second current is essentially the first current

Proportional, and in the correct connection direction, the phase difference between the second current and the first current is close to zero.

As an important equipment in power system, it is very important to test the electrical performance of the current transformer

The test is an indispensable test item. The current transformer ratio is related to the accuracy of measurement and the reliability of protection.

Current method is commonly used in the field variable ratio test of current transformers. Current method is used to measure the variable ratio of current transformers

The actual operating condition under is an ideal test method with high precision, but with the continuous development of the power system, a single generator

Its output current has reached tens of thousands of amperes.

For example, for an 800-mw generating set, the rated voltage is 20 kV and the rated current is 800/(20 * 31/2) = 23.094 kA, and the corresponding electricity is used

The primary current of the current transformer is very large. If the primary current of the current transformer is measured in tens of thousands of amperes by the current method, it is difficult to achieve it in the field:

First, rated high current is difficult to reach (high capacity voltage regulator is required);

Second, the required standard current transformer or current lifter is large in volume and high in cost. If the primary current of the current transformer under test is reduced, then

If the variable ratio error is large, the experiment is meaningless.