Product Overview
Currently, in the measurement of contact resistance in power systems, the conventional QJ44 double-arm DC bridge is commonly used. However, the test current of such bridges is only at the milliampere level, making it difficult to detect defects such as reduced cross-sectional area of circuit conductors. When measuring the contact resistance of high-voltage switchgear conductive circuits, due to the influence of oil films and oxide layers between contacts, the measured values can be several times larger, failing to accurately reflect the true contact resistance. To address this, the Ministry of Electric Power standard SD301—88 "Procedures for Handover and Preventive Tests of AC 500KV Electric Power Equipment" and the new edition of "Procedures for Preventive Tests of Electric Power Equipment" stipulate that the measurement current for contact resistance of circuit breakers and disconnectors shall not be less than DC 100A, ensuring accurate test results. This product is designed based on the latest Chinese electric power execution standard DL/T845.4-2004, combining high-frequency switching power supply technology with digital circuit technology. It is suitable for measuring the loop resistance of switch control equipment. The test current adopts the national standard recommended DC 100A and 200A. The loop resistance can be directly measured at a current of 100A, and also at a current of 200A, with the final test results displayed digitally. This instrument provides accurate measurements and stable performance, meeting the requirements for on-site high-voltage switch maintenance in power and power supply departments, as well as loop resistance testing in high-voltage switchgear factories.
