mportance than the absolute time of an event is its time relative to other events across the system.РThe new generations of protective relays now include their own sequence of event recording facilities. Moreover these facilities can be extended using spare relay input channels and separate I/O modules to cover events not specifically related to the protection. In order to achieve this a new method of time synchronization has been devized which removes the need for separate clock synchronization wiring. Rather than trying to synchronize the clocks within each individual relay, the relay clocks are allowed to free run. Events within each relay are time tagged relative to the internal free running clock. This is derived from the microprocessor's clock and resolutions of ± 1ms are obtainable.
全文预览
