Thermal Overload Protection, One Time Constant, Celsius/Fahrenheit Lcpttr/Lfpttr; Identification; Application - ABB Relion REC670 Applications Manual

Section 7
Current protection
See chapter "Inverse time characteristics" in Technical Manual for the description of different
characteristics
tPCrv, tACrv, tBCrv, tCCrv : Parameters for customer creation of inverse time characteristic
curve (Curve type = 17). The time characteristic equation is:
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EQUATION1958 V1 EN-US
tINNonDir is the definite time delay for the non directional earth fault current protection, given
in s.
OpUN> is set On to activate the trip function of the residual over voltage protection.
tUN is the definite time delay for the trip function of the residual voltage protection, given in s.
7.7 Thermal overload protection, one time constant,
Celsius/Fahrenheit LCPTTR/LFPTTR
7.7.1

Identification

Function description
Thermal overload protection, one
time constant, Celsius
Thermal overload protection, one
time constant, Fahrenheit
7.7.2

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:
• The sag of overhead lines can reach unacceptable value.
• If the temperature of conductors, for example aluminium conductors, gets too high the
material will be destroyed.
• In cables the insulation can be damaged as a consequence of the overtemperature. As a
consequence of this phase to phase or phase to earth faults can occur.
142
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B InMult
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in
IEC 61850 IEC 60617
identification identification
LCPTTR
LFPTTR
1MRK 511 358-UEN A
(Equation 60)
ANSI/IEEE C37.2
device number
26
26
Application manual
IP14512-1 v7
M17106-1 v7
M15283-3 v8