In power system, it can excite partial parallel resonance or serial resonance, enlarge the harmonic wave, trigger relay protection system in error and disturb electric power energy metering equipment.
It is applied in relay protection, system metering and analysis of power system. It has a close relation with the security and reliability of power system.
它被广泛应用于继电保护、系统监测、电力系统分析之中，关系到电力系统的安全性与可靠性。
3
The common faults of S1240 (ELC type) SPC exchange are in user mod ul e, relay module and metering module in daily maintenance work.