• In case a total interruption (low current) of the protected transformer allcooling possibilities will be inactive. This can result in a changed value of thetime constant.• If other components (motors) are included in the thermal protection, there is arisk of overheating of that equipment in case of very high current. The thermaltime constant is often smaller for a motor than for the transformer.ITrip: The steady state current that the transformer can withstand. The setting isgiven in % of IBase1 or IBase2.Alarm1: Heat content level for activation of the signal ALARM1. ALARM1 is setin % of the trip heat content level.Alarm2: Heat content level for activation of the output signal ALARM2. ALARM2is set in % of the trip heat content level.ResLo: Lockout release level of heat content to release the lockout signal. Whenthe thermal overload protection trips a lock-out signal is activated. This signal isintended to block switching on of the protected circuit transformer as long as thetransformer temperature is high. The signal is released when the estimated heatcontent is below the set value. This temperature value should be chosen below thealarm temperature. ResLo is set in % of the trip heat content level.ThetaInit: Heat content before activation of the function. This setting can be set alittle below the alarm level. If the transformer is loaded before the activation of theprotection function, its temperature can be higher than the ambient temperature.The start point given in the setting will prevent risk of no trip at overtemperatureduring the first moments after activation. ThetaInit: is set in % of the trip heatcontent level.Warning: If the calculated time to trip factor is below the setting Warning awarning signal is activated. The setting is given in minutes.7.6 Breaker failure protection CCRBRF IP14514-1 v67.6.1 IdentificationM14878-1 v5Function description IEC 61850identificationIEC 60617identificationANSI/IEEE C37.2device numberBreaker failure protection, 3-phaseactivation and outputCCRBRF3I>BFSYMBOL-U V1 EN-US50BFSection 7 1MRK 504 169-UEN ACurrent protection136 Transformer protection RET650 2.2 IECApplication manual
