OPTICAL CURRENT TRANSFORMER

摘要

PURPOSE:To achieve high measurement accuracy while enlarging the current measuring range. CONSTITUTION:The optical current transformer comprises core type optical current transformers 211-217 provided with a gap, and coreless optical current transformers 231-236 having higher current measuring range than the optical current transformers 211-217. A demodulation selecting section 24 selects the outputs from the optical current transformers depending on the magnitude of current flowing through a conductor 22 to be measured and demodulates the selected output to produce a current detection output. When the magnitude of current is relatively low, detection outputs from the transformers 211-217 are taken out otherwise detection outputs from the transformers 231-236 are taken out. Measurement accuracy is enhanced for both detection outputs and the measurement range is enlarged by selecting the transformers.