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1.Overview
At present, the measurement of contact resistance in the power
system generally uses the conventional QJ44 type double-arm DC
bridge, and the test current of this type of bridge is only mA level, it
is difficult to find the defect of reducing the cross-sectional area of
the loop conductor, and the contact of the high-voltage switch
conductive loop is measured. In the case of resistance, the
measured value is somewhat larger due to the influence of the oil
film and the oxide layer between the contacts, and the contact
resistance value cannot be truly reflected. To this end, the Ministry
of Power Standard SD301-88 "AC 500KV power equipment
handover and preventive test procedures" and the new "Power
Equipment Preventive Test Procedures" to make the measurement
current of the circuit breaker, isolation switch contact resistance is
not less than DC 100A, To ensure accurate test results.
The instrument is designed according to the latest power standard
DL/T845.4-2004 of the People's Republic of China, using
high-frequency switching power supply technology and digital
circuit technology. It is suitable for the measurement of the loop
resistance of switch control devices. The test current is DC 100A
and 200A recommended by national standards. The loop
resistance can be measured directly at a current of 100A, or the
loop resistance can be directly measured at a current of 200A. The
