Resonance frequency measurement for small relay using magnetization current perturbation method; Invention and the demonstration of the new seismic test method

Imamoto, Nobuo ; Koiso, Keiichi

The shaking table tests have been employed to evaluate the seismic fragilities of the machine-electric equipments. Through the shaking table test, in ordinarily it is depending on resonance frequency, repetitive adjustments are needed to search a normal/malfunction boundary. However, a small relay used for the electric panel and the control system, can not be measured the resonance frequency because the acceleration sensor installation affects the vibration characteristic of the test body. And more, the moving parts leading to a relay malfunction is settled in the case, it can not be carried out direct measurement of the vibration. To improve the shaking table test methods, magnetization current perturbation method was invented and developed. Instead the mechanical shaking force, magnetization current perturbation method employs vibrating electromagnet force. Moreover, obtained impedance characteristic curve, the resonance frequency can be obtained by fitting to a theoretical curve. This paper deals with the principle of the magnetization current perturbation method, theoretical derivation of impedance, measurement electronics circuit, and system design and test results.