Coding techniques for secure digital communications for unit protection of distribution feeders

The dramatic growth in new designs of microprocessor relays has led to a growth in the use digital communications for protection. Unfortunately in any communication system there will always be some corruption of the received data. Part of the art and science of relay design is therefore to take this into account. This paper examines coding techniques designed to minimise the probability of corrupted data being declared as healthy. Message size, coding techniques and interleaving are examined with respect to the choice of a coding strategy for a secure data communication system for unit protection.