Dc resistance tester has high accuracy and easy operation. It is suitable for distribution transformers, transformers, reactors, generators, motors and other test products. It can also be used for quick measurement of switches, copper bars, contactors, relay contacts, metal wires, cable accessories and other test products.
When we use the DC resistance tester, when the measured resistance exceeds the limit, we should pay attention to the following points:
1. The resistance value of dc resistance is greatly affected by temperature, so it must be converted to the same temperature (usually 20℃, R20=(T+20)/(T+T), T copper =235) for comparison, and generally based on the oil temperature of the upper layer.
2. First consider whether there is measurement error (such as whether the external lead is connected, test whether the lead is too long or too thin, whether the contact is good, whether the battery voltage in the bridge is insufficient).
3. Poor contact of tap switch leads to high resistance, such as clean electroplating off switch, insufficient spring pressure, uneven stress and carbon accumulation of overvoltage contact, which will cause resistance conduction. At this time, tap switch cover should be opened, rotating a few times, generally can be eliminated.
4. In the current three-phase distribution transformer, the high voltage winding adopts Y-shaped wiring. When the resistance value exceeds the limit value, the following formula [RA=(RAB+ RAC-RBC)/2, RB=(RAB+ RAC-RAC)/2, RC(RBC+ RAC-RAB)/2] can also be used to find the defective phase.
Wuhan Xinshengneng Technology Co., Ltd. specializes in the production of transformer test series test equipment, the production of a variety of products, complete models, cost-effective products, guaranteed service, welcome to call 0312-3188565 consultation!
