The current status of the transformer temperature rise test integrates the power monitoring and temperature measurement in the test to automatically control the test process, and can cooperate with the PC. Use the advantages of the PC to more conveniently perform data processing and automatic control, reducing Manual intervention increases the accuracy of the test and improves the automation of the power transformer temperature rise test process.

The temperature rise test automatic control system introduces microcomputer technology, which can not only automatically measure and record the relevant temperature, make judgments, but also measure the relevant electricity in the test to monitor the total loss of the tested transformer and other important parameters in real time, and It can automatically adjust the test power supply when it deviates from the preset value.

Principle of temperature rise test

There are several methods for conducting transformer temperature rise test: direct load method, mutual load method, circulating current method, zero sequence current method, and short circuit method.

The short-circuit test is to use the short-circuit loss of the transformer to conduct the temperature rise test. At present, the short-circuit method is generally used. The temperature rise of the short-circuit method is the test that requires the smallest power supply capacity and low test voltage Z among all the transformer temperature rise tests. The method is a commonly used method for temperature rise test of large oil-immersed transformers.

Experimental procedure

Use the short-circuit method to carry out the temperature rise test. First determine the test power supply capacity and test current, connect the test circuit, and then start the test. During the test, monitor the loss and current added to the tested transformer and compare with the set value. If it exceeds the allowable Error range, adjust the test power supply, and test the temperature of the test part once after a predetermined time interval (usually at an interval of 15 to 30 minutes), and record and judge the measurement results until the rate of change of the detected top oil temperature rise is less than 1K/ h, and continue to maintain for 3h, it is considered that the temperature rise of the top oil layer has stabilized, and the average value in the last hour is taken as the temperature rise of the top oil layer. After that, the second phase of the test is started: winding temperature rise test (measurement of thermal resistance, cold The state resistance has been measured before the temperature rise test).