To ensure a transformer operates properly, the following tests should be performed regularly:

(1) Temperature Test. The operating temperature is a critical indicator of a transformer's health. Regulations stipulate that the top oil temperature must not exceed 85°C (a temperature rise of 55°C). Most transformers are equipped with dedicated temperature measurement devices.

(2) Load Measurement. To improve transformer utilization and reduce energy loss, it is essential to measure the actual load capacity of the transformer during operation. This measurement is typically taken during peak electricity usage hours each season using a clamp-on ammeter. The current should ideally be 70-80% of the transformer's rated current. If it exceeds this range, it indicates an overload, and immediate adjustments should be made.

(3) Voltage Measurement. Regulations require the voltage variation to remain within ±5% of the rated voltage. If the voltage exceeds this range, the tap changer should be adjusted to bring it within the specified limits. Generally, a voltmeter is used to measure the voltage at the secondary coil terminals and at the end-user's terminals.