A discussion on the reliablilty of static relays is made in this thesis , because some new problems have arisen after static relays are applied on the relayprotection of electric system .
In power system, it can excite partial parallel resonance or serial resonance, enlarge the harmonic wave, trigger relayprotection system in error and disturb electric power energy metering equipment.
In the system of relayprotection of electric power, abnormal state information given by relayprotection devices has two types: accident information message and warning information message.