Thermal Overload Protection, One Time Constant Fahrenheit Celsius Lfpttr/Lcpttr (26) - ABB RES670 Technical Manual

1MRK 511 408-UUS A
8.5
8.5.1
8.5.2
Phasor measurement unit RES670 2.2 ANSI
Technical manual
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
Functionality
The increasing utilization of the power system closer to the thermal limits has
generated a need of a thermal overload protection for power lines.
A thermal overload will often not be detected by other protection functions and the
introduction of the thermal overload protection can allow the protected circuit to trip
closer to the thermal limits.
The three-phase current measuring protection has an I
time constant and a thermal memory. The temperature is displayed in either Celsius or
Fahrenheit, depending on whether the function used is Thermal overload protection
(Fahrenheit) LFPTTR (26) or Celsius (LCPTTR).
An alarm pickup gives early warning to allow operators to take action well before the
line is tripped.
Estimated time to trip before operation, and estimated time to reclose after operation
are presented.
IEC 61850 IEC 60617
identification identification
LFPTTR
LCPTTR
2
t characteristic with settable
Section 8
Current protection
IP14512-1 v7
M17106-1 v7
ANSI/IEEE C37.2
device number
26
26
M12020-4 v14
243