Product Overview
Currently, the conventional QJ44 double-arm DC bridge is commonly used in power systems for measuring contact resistance. However, the test current of such bridges is only in the mA level, making it difficult to detect defects such as reduced cross-sectional area of circuit conductors. When measuring the contact resistance of high-voltage switch conductive circuits, the measured value can be several times larger due to the influence of oil film and oxide layer between contacts, 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 Power Equipment" and the new edition of "Procedures for Preventive Tests of Power Equipment" stipulate that the measurement current for contact resistance of circuit breakers and disconnectors shall not be less than DC 100A to ensure accurate test results. This product is designed based on the latest Chinese electric power executive 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 DC 100A and 200A as recommended by national standards. The loop resistance can be directly measured at a current of 100A, or directly measured at a current of 200A, with the final test results displayed digitally. This instrument offers accurate measurement 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 switch factories.
