Triple Frequency Test Set Product Overview
The induced overvoltage withstand test for transformers and instrument transformers is an important test to ensure that transformer quality meets national standards. The longitudinal insulation induced overvoltage withstand test for inter-turn, inter-layer, inter-section, and inter-phase insulation of transformer windings is a key item in transformer insulation testing. Due to the particularity of the longitudinal insulation test, it is necessary to apply a frequency-multiplied power supply device to increase the test voltage across the winding insulation, thereby achieving the purpose of the withstand test.
Triple Frequency Test Set is designed and manufactured to meet the above requirements. It has been proven by extensive user experience that it is simple to operate, reliable in performance, and can effectively meet the needs of induced overvoltage withstand tests for transformers and instrument transformers.
During measurement, a low voltage U1 is applied to the primary side of the transformer under test, and a voltage U2 appears on the secondary side. By adjusting the resistance value of R3, the galvanometer can be brought to zero. At this point, the turns ratio k can be calculated using the following formula (R3 is much smaller than R2 and R1, so R3 is neglected):
k = U1 / U2 = (R1 + R2) / R2 = 1 + R1 / R2
To directly read the ratio error, a slide wire resistor R3 can be inserted between R1 and R2, with one end of the galvanometer connected to the sliding contact. Different resistance values of the slide wire resistor R3 are marked on the bridge panel with different ratio errors, allowing direct measurement of the ratio error.
Using the transformer ratio bridge method to measure the turns ratio of a three-phase transformer is similar to the dual voltmeter method. It also uses a single-phase power supply, and a switching circuit is built into the bridge to perform measurements according to different connection groups and different measurement modes (voltage application, short circuit, measurement). Therefore, when conducting a ratio test using the transformer ratio bridge method, it is necessary to connect the wires correctly and operate properly according to the instruction manual.
The above is the method of measuring transformer turns ratio using the transformer ratio bridge method. In the absence of a transformer turns ratio tester, this method can be used to measure the transformer turns ratio. SBF Triple Frequency Test Set Working Principle
