Certification of current transformers at operating voltages

Conclusions

Theoretical expressions for the error$\dot \gamma _u$ caused by the voltage between windings$\dot U_3$ in current transformers have been experimentally confirmed. The investigated type I-512 laboratory transformers have been found to have an error$\dot \gamma _u$ greater than specified by their class of accuracy.

Technical documentation of current transformers [2, 3] should specify current transformer errors due to their operating voltages. The standard [1] should be supplemented with a definition of current transformer errors due to operating voltages, and recommend verification methods similar to those described here.

In acceptance and performance tests as well as in the course of current-transformer production the$\dot \gamma _u$ error should be determined under operating-voltage conditions and stated in the specifications. The results of metrological certification should be documented as stated in [9].