KRI9310 DC Resistance Tester-Yangzhou Darui

Darui Electric recommends



KRI9310 DC Resistance Tester is widely used in post and telecommunications, scientific research, hospitals, factories, schools, etc. It adopts a typical four-wire measurement method to improve the accuracy of measuring resistance (especially low resistance). The programmable constant current source, programmable preamplifier, and A/D converter constitute the main body of the measurement circuit. The central control unit applies a constant, high-precision current to the external load under test by controlling the constant current source, and then processes the obtained data (including test voltage, current test current, etc.) to obtain the actual resistance value.


This tester is not only suitable for inductive test objects such as distribution transformers, mutual inductors, reactors, and electromagnetic operating mechanisms, but also for resistive test objects such as wires, switch contacts, and relay contacts. For dry-type transformers and amorphous alloy transformers, since the low-voltage coils are wound with copper foil and the resistance value is low, this instrument increases the current to 10A, solving the problem of low-value resistance measurement.


When using the KRI9310 DC resistance tester, if the measured resistance value exceeds the limit, pay attention to the following points:


1.DC resistance is greatly affected by temperature, so it must be converted to the same temperature (usually 20°C, R20=(T+20)/(T+T), T copper=235) for comparison, and generally based on the top oil temperature.


2、First consider whether there is a measurement error (for example, whether external leads are connected, whether the test leads are too long or too thin, whether the contact is good, and whether the battery voltage in the bridge is insufficient).


3、Poor contact of the tap changer, leading to high resistance values, is relatively common. For example, if the switch plating is worn off, spring pressure is insufficient, stress is uneven, and carbon deposits on overvoltage contacts, all can cause resistance value conduction. At this time, the tap changer cover should be opened and turned several times, which can generally eliminate the problem.


4、For the currently used three-phase distribution transformer, the high-voltage winding adopts Y-connection. When the resistance value exceeds the limit, the following formulas can also be used [RA=(RAB+rac-rbc)/2, RB=(RAB+rac-rac)/2, RC(RBC+rac-rab)/2] to find the defective phase.


I hope the above content can help everyone better understand this tester.







Note: The above information and technical parameters are compiled and released by Yangzhou Darui Electric Co., Ltd.