Abstract
It is stated that the problem of designing relay protection devices without current transformers remains relevant. To address this issue, it is proposed to use magnetically operated contacts—reed switches. It is noted that principles and several protection devices based on reed switches have already been developed, including the differential protection of the transformer in the converter installation. However, a drawback of this protection system is its limited operational reliability due to the lack of current circuit integrity monitoring. To mitigate this issue, it is proposed to integrate three transreactors, two null indicators, three current relays, three voltage limiters, three phase-shifting circuits, three TIME elements, and one OR element into the protection device. It is emphasized that this approach will significantly reduce potential protection failures by ensuring continuous monitoring of the integrity of the current circuits and promptly notifying maintenance personnel (through signaling) of any emerging faults. The behavior of the protection system under various operating modes of the converter installation, as well as the process of detecting faults in the current circuits, is analyzed.