The use of PLCs in remedial action schemes

Programmable logic controllers (PLC) are a useful tool in the construction of remedial action schemes (RAS). RAS are special transmission system protection schemes designed to detect specific transmission disturbances and remediate a disturbance by changing the network configuration. This document describes the experiences of the Bonneville Power Administration (BPA) in the use of programmable logic controllers in remedial action schemes. Requirements fur using PLCs in RAS are detailed. Current installations are described and advantages and disadvantages of PLC use are discussed