ABSTRACT

A digital protective relay (DPR) consists of the following basic materials: an analog input block, input filters, a multiplexor, an analog-to-digital converter, a microprocessor, different memory devices, a logic inputs block, and a relay-controlled output block. When sliding the boards into the DPR enclosure on the guide rails, the board connectors plug into the sockets on base board, and thus the boards are connected with each other. The DPRs are based on surface-mount technology. The microprocessor is the central DPR assembly controlling the operation of all other assemblies and performing arithmetic and logical data operations. The design of output relay assemblies is a little more complicated. The structure of the DPR is made up of a set of printed circuit boards (PCB) corresponding to different functional parts, which are installed in enclosures of different types and sizes. The PCBs should be fastened to each other by way of connectors and a flat flexible lead.