Current transformer protector (P-class) accurate limiting factor measurement method - Database & Sql Blog Articles

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Verify that the current transformer protector (P-class) accurately limits the coefficient to meet the requirements of two methods, the excitation curve measurement method and the simulated secondary load method.
Excitation curve measurement method:
The excitation curve of the P-class winding should be determined by the nameplate parameter of the base current transformer. The secondary resistance R2 can be replaced by the secondary DC resistance R2. The leakage resistance X2 can be estimated, and the voltage and current are measured by the meter.
Simulated quadratic composite method:
When performing the basic error test, if the corresponding simulated secondary load is configured, it can indirectly check whether the accurate limit coefficient meets the requirements.
The nameplate of the current transformer is the same as above, and the secondary load Z is taken on the basic error line of the current difference method.
Note: Since the indirect method measurement does not consider the influence of the magnetic field interference caused by the primary conductor and the return conductor current, the indirect method is usually used to verify the qualified transformer. The result is not necessarily qualified. The indirect method is used to measure the unqualified transformer direct method. The measurement results are basically inconsistent, but the indirect method measurement method is simple and easy;
When there is suspicion, it is advisable to measure the composite error by the direct method, and the root measurement results determine whether it is qualified.