Thermal Overload Protection, One Time Constant Fahrenheit/Celsius Lfpttr/Lcpttr (26) - ABB REL650 Applications Manual

1MRK 506 334-UUS A
7.9
7.9.1
7.9.2
Application manual
I2Mode: number of phases involved for operation for step2.
I2<: high-set level of the current. If the current decreases below this limit the function
picks up and issue start signals PU_ST2 and RI.
t2: time delay of I2< from the pick-up to the issue of trip signals TRST2 and TRIP.
tReset2: instantaneous or time delayed reset of RI and PU_ST2 signals.
tPulse: duration of all TRIP signals.
IBlk: set level of the currents. If all three phase currents are below this limit the function
blocks the undercurrent protection.
The pick-up level for I1< and I2< should be set with some margin to the lowest current
level, that can appear during normal operation conditions.
Thermal overload protection, one time constant
Fahrenheit/Celsius LFPTTR/LCPTTR (26)
Identification
Function description
Thermal overload protection, one time
constant, Fahrenheit
Thermal overload protection, one time
constant, Celsius
Application
Lines and cables in the power system are designed for a certain maximum load current
level. If the current exceeds this level the losses will be higher than expected. As a
consequence the temperature of the conductors will increase. If the temperature of the
lines and cables reaches too high values the equipment might be damaged:
IEC 61850 IEC 60617
identification identification
LFPTTR
LCPTTR
Section 7
Current protection
ANSI/IEEE C37.2
device number
26
26
227