Fibre=optic interferometer for polyphase electric current measurement - uses Faraday effect with reference circuit in earthed base

摘要

The current is measured conventionally by its Faraday shift of the phases of two light waves from a laser source, circulating in opposite directions through an optical fibre. The cable (2) carrying the current passes through a measuring head (12) where at least one turn of the fibre is wound around it. The head (12) is supported by a rigid cylindrical or conical insulating column (13) with an exterior channel (130) in which the fibre is laid. The fibre extends pref. several times from the base (14) to the head (12) and back to the base, in which it is wound a number of times around a negative-feedback winding. The optical core of the interferometer is connected by electric and optical cable (150) to an electronics package (15).