Studies of principle and method to depress the air-gap effect to the clamp-on micro-current transducer

The amplitude-phase characteristic of the transducer and the effect of the gap to the magnetic resistance, inductance and mutual inductance of the transducer are analyzed by the equivalent model of passing through clamp-on micro-current transducer. Because of the gap, the lower limiting frequency of the transducer increase and the bandwidth turn narrow, as well as the voltage induced by the coil of the transducer is so feebleness and easy to be interfered that it is difficult to be measured accurately, which is a well-known difficult problem in the portable type measurement of the low-frequency feeble current signal. In this paper, a new method with design principle and the simulation result by Saber to reduce the effect of the gap in the transducer is introduced. The academic lower limiting frequency of the transducer is nearly zero and the upper limiting frequency is infinity. The test of the current transducer shows that the low limiting frequency of the transducer is improved, which can be use in most systems to reduce the effect of gap with broad pass-bandwidth, high linearity and high sensitivity.