Svrha DC otpornika za mjerenje DC otpora namotaja namotaja transformatora je da provjeri kvalitet zavarivanja spojeva namotaja i da li postoji kratki spoj između namotaja. Da li je kontaktni položaj prekidača naponske slavine dobar, da li se stvarni položaj slavine poklapa; da li je žica prekinuta. Nasukane žice i namotaji su pokidani. Prilikom remonta transformatora, ili nakon promjene položaja slavine, ili nakon kratkog reduciranja kvara na izlazu, potrebno je izmjeriti DC otpor namotaja i čahure.
Metoda mjerenja testera DC otpora transformatora je sljedeća:
(1) Struja, voltmetarska metoda, poznata i kao metoda pada napona, princip je mjerenje pada napona na otporu kroz jednosmjernu struju u izmjerenom otporu i izračunavanje izmjerene vrijednosti otpora prema Ohm39; zakonu. Budući da će unutrašnji otpor ampermetra i voltmetra utjecati na rezultate mjerenja, pažljivo razmotrite kako su spojeni na mjerni krug.
(2) Balanced bridge method. This is a method that uses the principle of bridge balance to measure the resistance of the DC winding. Commonly used balanced bridges include single reduce arm bridges and double reduce arm bridges. When measuring the DC winding resistance of the transformer, the transformer DC resistance tester should be performed after the transformer is powered off and the high reduce voltage wire is removed. For large and large reduce capacity power transformers, the charging time constant τ of the rl series circuit is very large, so that each measurement takes a long time to wait for the current and voltmeter to indicate stable, so the work efficiency is very low, and special instruments (such as constant Current). Replacing the power supply in the test with a power supply can greatly reduce the test time. The standard for measuring the DC winding resistance of transformer coils is: For transformers above 1600 kva, the difference in resistance of each phase winding should not exceed 2 percent of the three reduce phase average value, and the neutral line should have no winding point lead wire. The difference between the lines should not be greater than 1 percent of the average value of the three phases. For transformers of 1600kva and below, the difference between the phases is generally not greater than 4 percent of the three reduce phase average, and the difference between the lines is generally not more than three reduce phase. 2 percent of the average value, compared with the measured value in the previous part, its change should not exceed 2 percent . And the neutral point lead wire should not be twisted. The difference between the lines should not be greater than 1 percent of the average value of the three phases. For transformers of 1600kva and below, the difference between the phases is generally not greater than 4 percent of the three reduce phase average, and the difference between the lines is generally not more than three reduce phase. 2 percent of the average value, compared with the measured value in the previous part, its change should not exceed 2 percent . And the neutral point lead wire should not be twisted. The difference between the lines should not be greater than 1 percent of the average value of the three phases. For transformers of 1600kva and below, the difference between the phases is generally not greater than 4 percent of the three reduce phase average, and the difference between the lines is generally not more than three reduce phase. 2 percent of the average value, compared with the measured value in the previous part, its change should not exceed 2 percent .