Investigative Methods for Anti-Theft of Electricity (3)

3. Check the transformer

Mainly check whether the nameplate parameters of the metering transformer are consistent with the user manual, check whether the transformation ratio and group selection of the transformer are correct, check the actual wiring and transformation ratio of the transformer, and check whether the operation of the transformer is normal.

(1) Check whether the nameplate parameters of the transformer are consistent with the user manual. High-supply high-meter users check the voltage and current transformers at the same time, high-supply low-meter users and ordinary low-voltage users prevent them from stealing and changing columns.

(2) Check whether the transformer ratio selection is correct.

A. The selection ratio of the voltage transformer should be consistent with the rated voltage of the electric energy meter.

B. The selection ratio of the current transformer should meet the requirements of accurate measurement, and the actual load current should be in the range of 30%-100% of the rated current of the current transformer. The maximum is not more than 120% of the rated current, and the minimum is not less than 10% of the rated current.

C. The voltage connection group should correspond to the current connection group to ensure the normal phase relationship between the current and voltage.

(3) Check the actual wiring and transformation ratio of the transformer.

A. Check the voltage transformer wiring and transformation ratio.

B. Check the current transformer wiring and transformation ratio. Since the current transformer is usually made with multiple transformation ratios, different transformation ratios can be obtained by changing the number of turns on the primary side.

(4) Check the operation of the transformer.

A. Observe whether there is any disconnection or overheating or scorching on the surface.

B. Listen to see if the sound is normal, there will be a clear humming sound when the current transformer is open.

C. Check the voltage and current transformers immediately after the power failure. When the voltage transformers are overloaded or the current transformers are open, there is a burning sensation when touching the limbs. When the voltage transformers are open, the temperature will be significantly lower than the normal value. When the internal fault of the voltage and current transformers cause overheating, there will also be odors such as the volatilization of insulating materials when heated. Need to observe carefully.