Measurement of isolating resistance with parallel coil - using alternating voltage frequency such that coil impedance is at least one hundredth of leakage resistance

摘要

A method of observing variations in the impedance of high resistance isolating resistors with parallel coils of relatively low inductive uses conventional instruments without constructional modification. The method is economical and accurate and permits measurements to be made when the equipment contg. the resistance is in use. An alternating voltage is applied to the circuit contg. the resistance, which operates with direct voltage. The alternating voltage frequency is chosen such that the impedance of the coil is at least one hundredth of the leakage resistance of the isolation resistance which is to be measured. The impedance measurement is then performed using an alternating current bridge of the deflection-or-balance-reading type.