Several points that should be paid attention to when operating dc resistance tester

Dc resistance tester in the process of measurement, in addition to strictly abide by the electrical safety rules and equipment test rules, but also pay special attention to the coil temperature under the condition of stable measurement, the transformer oil tank, the lower temperature difference is not more than 3℃. Because of the inductance of the transformer coil, the charging current is not stable when measured. It must be counted after the current is stable. If necessary, measures should be taken to shorten the charging time. Reduce the contact resistance of the conductor in the test loop as far as possible. The transformer tap in operation is often affected by dirt such as oil film so that it is in poor contact. Generally, it needs to be changed several times before measurement, so as not to cause discrimination errors. When measuring the low-voltage side of the transformer, all personnel should keep a proper safety distance from the high-voltage side.

Dc resistance tester in transportation, storage and work should avoid strong vibration, direct sunlight and magnetic field, storage and storage of the instrument, should pay attention to the environmental temperature and humidity, should be placed in a dry, ventilated, non-corrosive gas place is appropriate, not damp, rain, exposure to the sun, when using gently, gently put, do not fall. It can check whether the conductive loop of the equipment has defects such as bad contact, bad welding, coil fault and wiring error. In the actual measurement of medium and small transformers, dc bridge method is mostly used. When the resistance value of the tested coil is above 1 euro, it is generally measured by single arm bridge, and below 1 euro, it is measured by double arm bridge. When using double-arm bridge wiring, the potential pile head of the bridge should be close to the measured resistance, and the current pile head should be connected above the potential pile head.

Dc resistance tester measures before, should first to estimate the resistance value of the measured coil, the selection of the bridge rate button in the appropriate position, will not be measured coil short circuit and grounding, then open the power switch, after being sufficient electricity to press the galvanometer switch, quickly adjust measuring arm, make to the galvanometer galvanometer pointer scale in the middle of the zero line direction, fine-tuning. When the pointer stops at zero, record the resistance value. At this time, the resistance value of the measured coil = the multiplier number × the resistance value of the measuring arm. After the measurement, open the galvanometer button and then release the power switch.

Dc resistance tester measures before, should first to estimate the resistance value of the measured coil, the selection of the bridge rate button in the appropriate position, will not be measured coil short circuit and grounding, then open the power switch, after being sufficient electricity to press the galvanometer switch, quickly adjust measuring arm, make to the galvanometer galvanometer pointer scale in the middle of the zero line direction, fine-tuning. When the pointer stops at zero, record the resistance value. At this time, the resistance value of the measured coil = the multiplier number × the resistance value of the measuring arm. After the measurement, open the galvanometer button and then release the power switch.