In order to ensure the normal operation of the transformer, the following tests should be carried out frequently:
(1) Temperature test.
Whether the transformer is operating normally or not, the temperature is very important. The regulations stipulate that the upper oil temperature shall not exceed 85°C. Generally, transformers are equipped with special temperature measuring devices.
(2) Load measurement.
In order to improve the utilization rate of the transformer and reduce the loss of electric energy, in the operation of the transformer, it is necessary to determine the power supply capacity that the transformer can really bear. The measurement is usually carried out during the peak period of electricity consumption in each season, and it is directly measured with a clamp ammeter. The current value should be 70-80% of the rated current of the transformer. If it exceeds, it means overload, and it should be adjusted immediately.
(3) Voltage measurement.
The regulations require that the voltage variation range should be within ±5% of the rated voltage. If it exceeds this range, a tap should be used to adjust the voltage to reach the specified range. Generally, a voltmeter is used to measure the terminal voltage of the secondary coil and the terminal voltage of the terminal user respectively.
(4) Measurement of insulation resistance.
In order to keep the transformer in normal operation at all times, the insulation resistance must be measured to prevent insulation aging and accidents. When measuring, try to stop the operation of the transformer. Use a shaker to measure the insulation resistance of the transformer. The measured resistance is required to be no less than 70% of the previously measured value. When the shaker is selected, the low-voltage coil can use 500 volts.