Current transformers for frequencies 14 Hz to 100 Hz for use with electrical measuring instruments and electrical protective devices. Ratings; accuracy; tests; rating-plate and terminal markings. Appendices on guidance in application of current transformers: short-time rating; maximum V A output of bar-primary and bushing current transformers; use of current transformers for dual purpose of measurement and protection, composite error, high and low reactance current transformers.Replaced by BS 7626:1993 but remains current and has been proposed for withdrawal.