DC resistance measurement is an important item in transformer maintenance. The quality of the coil, whether the contact position of the tap switch is good, whether the coil or wire is broken, the correctness of the parallel branch and whether there is a short circuit can be checked by measuring the DC resistance of the winding. Determine the important data of short-circuit loss. Therefore, the test shall be conducted after switching, pre-test, overhaul and replacement of the tap switch. However, with the increase of power system capacity, the transformer capacity is also increasing. The larger the transformer capacity, the higher the voltage level, and the larger the ratio of inductance to resistance. Therefore, the stability time of DC circuit of large transformer winding may be tens of minutes or even longer. Therefore, in order to meet the needs of rapid measurement of transformer DC resistance, our company has developed ZC-205A DC resistance tester by using its own technical advantages.
Advantages of ZC-205A DC resistance tester：
1. high efficiency and fast DC power supply is adopted, and the opening voltage can reach 24V, which can quickly charge and discharge the transformer winding.
2. the test precision is high. The instrument adopts 16 bit high-precision AD converter with CPU and DSP (digital signal processing) chip, which effectively ensures the measurement precision and anti-interference ability.
3. each test can display and print all the test data of the three-phase winding of the transformer, automatically calculate the three-phase unbalance rate, and display and print the resistance value converted to the rated temperature.
4. it has perfect over-current protection and wiring inspection functions.
5. 320x240 large screen, high brightness liquid crystal display, all Chinese character menu and operation tips realize friendly man-machine dialogue, with its own real-time electronic clock, and automatically record the date and time of the test, which is conducive to the storage and management of the test results.
6. the data has the functions of power down storage and browsing, and can store 1000 groups of experimental results.
7. it has sound and LCD indicating discharge alarm, clear discharge index and reduced misoperation.
8. it has RS232 communication interface to support online operation.
ZC-205A DC resistance tester of our company is a high-precision replacement product that replaces DC single and double arm electric bridges. The advanced switching power supply technology is adopted, and the measurement results are displayed by dot matrix LCD. It overcomes the disadvantage of other similar products that the LED display value is inconvenient to read in the sun, and has the function of automatic arc suppression. The DC resistance test of transformer winding is an essential test item after transformer handover, overhaul and change of tap changer. Under normal circumstances, it is a time-consuming and laborious work to measure the DC resistance of transformer windings and high-power inductive equipment by traditional methods (bridge method and voltage drop method). It can be seen that the kst-205a DC resistance tester developed by our company has a very powerful function and principle, which facilitates many unnecessary steps, shortens the measurement time and reduces the workload of testers.