WJHL-100A Loop Resistance Tester The loop resistance tester is designed by combining digital circuit technology and switching power supply technology. It is suitable for the measurement of contact resistance and loop resistance of switching control equipment. The test current adopts the DC 100A recommended by the national standard. The loop resistance and contact resistance can be measured directly at a current of 100A and displayed digitally. The instrument has accurate measurement and stable performance, which is suitable for the on-site maintenance of high-voltage switchgear in the power and power supply departments and the circuit resistance test of high-voltage switchgear plant.