The function of DC winding resistance tester is to detect the winding resistance of transformers, motors and other windings, this instrument circuit will exist inductive reactance or capacitive reactance, so it is impossible to enter the high-current test, unless the instrument has a large capacity of the test device, otherwise it is difficult to use.
The general resistance value of the contact resistance tester is very small, which is microohm level, which refers to the on-contact resistance of the disconnector and circuit breaker. However, the contacts of these devices are prone to oxidation. Therefore, the oxide film must be destroyed after the large current is passed during the detection, so that the true DC resistance value of the circuit can be tested. There is no impedance in this curcuit, so the resistance can be quickly measured once the current is applied.
These two testers are used to test resistance, in the method are the use of DC voltage drop method, there are many people who do not understand this will think that it is the same, can be used interchangeably, but in essence there is still a difference between the two, from the test product, loop resistance tester test is mainly resistive load, and are microresistance test, DC resistance tester test is mainly inductive load, resistive range is relatively large, the two can not be used interchangeably, for example, If a loop resistance tester is used to measure the inductive load, it will damage the equipment. At present, there are still no two instruments on the market of synthetic type, if you want to combine two devices into one device, then you have to meet the high current, but also to meet the test resistance relatively large inductive load, so that it is more troublesome, and the cost is also very high, the equipment volume is also very large.