|Release time: 2017-08-28 Click times: 1372 times|
Transformer DC resistance tester is referred to as DC resistance tester, direct resistance tester, inductive load DC resistance tester and so on. Text name: Transformer DC Resistance Tester. Transformer DC resistance tester is a new type of instrument designed to measure the DC resistance of large-capacity transformers. It is a high-precision current-stabilizing power supply and testing part designed into one. It is controlled by a computer during the test process and automatically completes steady-state judgment, data acquisition, data processing, and resistance measurement. Value display and printing. The instrument can be used for one-time power supply for the longitudinal test of the on-load voltage regulator, which fully saves the test time. It also has a temperature rise test function for the transformer manufacturer. It can achieve fast and accurate measurement of various types of transformers, with simple operation, high accuracy, Anti-interference and other characteristics. The following describes the measurement methods and precautions of the transformer DC resistance tester.
1.Measurement method of transformer DC resistance tester
Measuring DC resistance is an important item in transformer tests. Through measurement, you can check the device's conductive circuit for defects such as poor contact, poor welding, coil failure, and wiring errors. In the actual measurement of small and medium-sized transformers, the DC bridge method is mostly used. When the resistance value of the coil under test is more than 1 ohm, it is generally measured by a single-arm bridge, and below 1 ohm, it is measured by a double-arm bridge. When using a two-arm electrical bridge line, the potential stake of the bridge should be close to the measured resistance, and the current stake should be connected above the potential pile. Before measuring, you should first estimate the resistance of the coil under test, set the bridge magnification selector to an appropriate position, short-circuit and ground the non-test coil, and then turn on the power switch to charge. After the battery is fully charged, press the galvanometer switch. Quickly adjust the measurement arm, move the galvanometer pointer toward the zero line in the middle of the galvanometer scale, make fine adjustments, and record the resistance value when the pointer stops at the zero position smoothly. At this time, the measured coil resistance value = multiplier ¡Á Measure the arm resistance value. After the measurement is completed, first open the galvanometer button and then release the power switch
2. Note for transformer DC resistance tester
In the measurement process, in addition to strictly observing the electrical safety regulations and equipment test regulations, special attention should be paid to:
1) The measurement is performed under the condition that the coil temperature is stable, and the difference between the upper and lower temperature of the transformer tank is not more than 3 ¡ã C;
2) Due to the inductance in the transformer coil, the charging current during measurement is not stable. Be sure to count after the current is stable. If necessary, take measures to shorten the charging time.
3) Minimize the contact resistance of the wires in the test circuit. The transformer taps in operation are often affected by dirt such as oil film to make poor contact. Generally, it needs to be switched several times before measuring to avoid discrimination errors.
4) When measuring the low-voltage side of the transformer, all personnel should maintain an appropriate safety distance from the high-voltage side.
5) The instrument should be protected from strong vibration, direct sunlight and magnetic fields during transportation, storage and work. When storing and storing the instrument, pay attention to the ambient temperature and humidity. It should be placed in a dry, ventilated and non-corrosive gas place. When it is wet, rainy or exposed to the sun, take it lightly and use it gently, and do not drop it.
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