One relevant ISO standard for relay protection is ISO 18488:2021, which specifies the requirements and recommendations for the application and integration of protective relays in power systems. Selectivity is a mandatory requirement for all protection, but the importance of it depends on the application. For example, unselective protection operation during a medium voltage network fault will cause an outage for an unnecessarily large number of consumers. While this is bad, It's not a. IEEE/IAS/I&CPSD Protection & Coordination WG Chair Jacobs Canada, Calgary, AB rasheek. Protective relaying is the backbone of fault detection and system isolation in As transmission systems grow increasingly complex with integration of. The recommendations and guidelines in this document are based on the experience and judgment of WECC members and include criteria for developing protection system best practices that, when implemented and used consistently, result in dependable, secure protection systems. In HV (High Voltage) and MV (Medium Voltage) substations, relay protection safeguards critical assets such as transformers, circuit breakers, and lines.
