• In case a total interruption (low current) of the protected transformer all
cooling possibilities will be inactive. This can result in a changed value of the
time constant.
• If other components (motors) are included in the thermal protection, there is a
risk of overheating of that equipment in case of very high current. The thermal
time constant is often smaller for a motor than for the transformer.
ITrip: The steady state current that the transformer can withstand. The setting is
given in % of IBase1 or IBase2.
Alarm1: Heat content level for activation of the signal ALARM1. ALARM1 is set
in % of the trip heat content level.
Alarm2: Heat content level for activation of the output signal ALARM2. ALARM2
is set in % of the trip heat content level.
ResLo: Lockout release level of heat content to release the lockout signal. When
the thermal overload protection trips a lock-out signal is activated. This signal is
intended to block switching on of the protected circuit transformer as long as the
transformer temperature is high. The signal is released when the estimated heat
content is below the set value. This temperature value should be chosen below the
alarm temperature. ResLo is set in % of the trip heat content level.
ThetaInit: Heat content before activation of the function. This setting can be set a
little below the alarm level. If the transformer is loaded before the activation of the
protection function, its temperature can be higher than the ambient temperature.
The start point given in the setting will prevent risk of no trip at overtemperature
during the first moments after activation. ThetaInit: is set in % of the trip heat
content level.
Warning: If the calculated time to trip factor is below the setting Warning a
warning signal is activated. The setting is given in minutes.
7.6 Breaker failure protection CCRBRF
IP14514-1 v6
7.6.1 Identification
M14878-1 v5
Function description
IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Breaker failure protection, 3-phase
activation and output
CCRBRF
SYMBOL-U V1 EN-US
50BF
Section 7 1MRK 504 169-UEN A
Current protection
136 Transformer protection RET650 2.2 IEC
Application manual
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