Abstract
It is noted that in relay protection, it is possible to ensure resource saving by building it on the basis of much less metal-intensive current sensors compared to traditional current transformers. It is indicated that a reed switch can be used for this purpose. On its basis, a simple scheme of the measuring device for current protection is proposed, which does not work falsely with short-term interference acting on the sensing reed switch. The method of calculating the parameters of the circuit elements of the measuring device is presented. Two variants of its improvement are proposed by the additional introduction of one or two reed switches to detect interference in the control circuits of the sensing reed switch, when magnetization is used to increase its sensitivity. The operation of measuring devices in various modes is described in detail.