1、ApplicationBreaker pole position discordance can occur on the operation of a breaker with independent operating gears for the three poles.The reason may be an interruption in the closing or trip coil circuit,or a mechanical failure resulting in a stuck(卡住的，不能动的)breaker pole.A pole discordance can be
2、 tolerated for a limited time,for instance during a single-phase trip-reclose cycle.The pole discordance function detects a breaker pole discordancy not generated by auto-reclose cycle and issues a trip signal for the circuit breaker.1.Pole discordance protection(PD)FunctionalityThe operation of the
3、 pole discordance logic,PD,it based on checking the position of the breaker auxiliary contacts.Three parallel normally open contacts in series with three normally closed contacts in parallel of the respective breaker poles form a condition of pole discordance,connected to a binary dedicated for the
4、purpose.In addition,there is an automatic detection criterion based on comparison of currents in the breaker poles.This function is enabled for just a few seconds after close or trip commands to the breaker in order to avoid unwanted operation in unsymmetrical load conditions.1.Pole discordance prot
5、ection(PD)The PHS is an independent measuring function.It comprises both impedance and current-based measurement criteria.Its main purpose is to augment the phase selectivity of the complete distance protection in networks with long and heavily loaded lines.It is generally intended for use in direct
6、ly earthed networks,where correct and reliable phase selection for single-phase faults,combined with single-pole tripping and automatic reclosing,secures the stability of complete power systems.The independent measurement of impedance in all fault loops secures a high degree of phase selectivity in
7、complex networks.This independent phase selection,combined with directional measurement for each fault loop,also secures selective operation for simultaneous close-in faults on parallel circuits.Independent reactive reach settings for phase-to-phase and phase-to-earth measurement secures high selectivity in networks with different protective relays used for short-circuit and earth-fault protection.返回
