Measuring Method of Transformer Direct-Current Resistance Tester
The transformer DC resistance tester is also called DC resistance tester, direct resistance tester, inductive load DC resistance tester and so on. The transformer DC resistance tester is a new instrument for measuring the DC resistance of large capacity transformer. It is composed of a high-precision steady current power supply and a test part. The testing process is controlled by microcomputer, and the steady flow judgement, data acquisition, data processing, resistance display and printing are completed automatically. The instrument can supply power at one time to carry out the longitudinal test of the load regulator, save time of test, and set up a temperature rise test function for transformer manufacturers. The rapid and accurate measurement of various types of transformers has the characteristics of simple operation, high precision and anti-interference.
METHOD OF MEASUREMENT
The measurement of DC resistance is an important item in the test of transformer. Through measurement, it can be found that the electrical circuit of the equipment has defects such as bad contact, bad welding, coil fault and connection error. In the actual measurement of medium and small transformers, the DC bridge method is mostly used. When the resistance value of the test coil is above 1 euro, it is generally measured by a single arm bridge. The 1 euro below is measured by two arm bridge. In the actual measurement of medium and small transformers, the DC bridge method is mostly used. When the resistance value of the test coil is above 1 euro, it is generally measured by a single arm bridge. The 1 euro below is measured by two-arm bridge.
In the use of a double-arm bridge connection, the potential pile head of the bridge is close to the measured resistance, and the current pile head should be attached to the top of the potential pile head. Before measuring, the resistance value of the measured coil should be estimated first, and the bridge multiplying ratio button should be placed in the appropriate position. The non – measured coil is short circuited and grounded, then the power switch is opened and charged. After full charge press galvanometer switch, quickly adjust the measuring arm, the galvanometer pointer to zero line direction in the middle scale galvanometer fine-tuning. The resistance value is recorded when the pointer is stationary on the zero position. At this time, the resistance value of the measured coil = the multiplying number * measurement arm resistance value. After the measurement, the first release of the galvanometer and then release the power switch button.