光学式磁束計による電力用変圧器の内部短絡検出への応用

抄録

An optical gaussmeter is proposed to detect an internal fault of a power transformer: when a turn short circuit occurs, the stray flux pattern changes from a symmetrical to an asymmetrical pattern.
The gauss meter uses a beam-guide type Faraday rotators as the field sensor and optical fibers as the transmission line. A laser beam travels through the Faraday rotators along multiple passes which are slightly canted from the leakage field, so that the field sensitivity of the rotators becomes very high. The minimum detectable leakage field is 1 G for 50 Hz. Analytical calculations as well as some experimental measurements are carried out to detect the position of an internal fault of a transformer.