Specifies the design, performance, testing requirements and application for dc auxiliary and input energising circuits of protection relays associated with measuring and tripping functions. It applies only to relays energised from dc supplies having nominal voltages of 30, 48 or 110V, and which may also be used for energising circuit breaker tripping or closing coils, or for other heavy current intermittent duty. Additional requirements are applicable to intertrip receive relays.