When purchasing a DC resistance tester, the rated current and resistance range of the device under test should first be clarified. For example, transformer winding DC resistance is usually in the milliohm to ohm range, while circuit breaker contact resistance is mostly in the microohm range. The ZDR-10A provides a 10A constant current output, suitable for measuring resistance in the 1μΩ to 2kΩ range, with a resolution of 0.1μΩ, and can meet the DC resistance testing needs of most power transformers, instrument transformers, and switchgear. If the object under test is 200A contact resistance, a model with a higher output current should be selected.
In DC resistance measurement, inductive effects can prolong the reading stabilization time. The ZDR-10A uses four-wire measurement and automatic demagnetization technology, ensuring 0.2% measurement accuracy while controlling the typical stabilization time to within 3 seconds. For three-phase transformers, single-phase/three-phase measurement modes can be switched, with per-phase recording and automatic calculation of the unbalance rate. Purchasing personnel should pay attention to whether the instrument has automatic discharge and back-EMF protection to avoid damage to the equipment from inductive loads.
The ZDR-10A has a built-in rechargeable lithium battery and can operate continuously for about 8 hours, making it suitable for substation sites without an external power supply. The panel is equipped with USB and RS232 interfaces, allowing test data to be exported to a PC for report generation. In terms of protection, the instrument housing reaches IP54 protection rating, and the anti-interference design complies with the relevant requirements of DL/T 845.3, allowing normal operation in ambient temperatures from -10℃ to 50℃. When purchasing, it is recommended to check the test lead length and clamp specifications to ensure they match the on-site wiring terminals.
During selection, output current, resistance range, accuracy, power supply method, and data management functions should be comprehensively considered. The ZDR-10A is positioned as a portable general-purpose model, suitable for routine DC resistance testing by county-level power supply companies, maintenance teams, and equipment manufacturers. If 200A contact resistance or ultra-low resistance values need to be measured, a dedicated contact resistance tester should be selected. It is recommended to request a metrological verification certificate before purchase to confirm that the instrument meets the traceability requirements of JJG 837 verification regulation for DC resistance boxes.
