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:
[ ] = + ×
-
>
æ ö
ç ÷
ç ÷
ç ÷
æ ö
ç ÷
ç ÷
è ø
è ø
p
A
t s B InMult
i
C
in
EQUATION1958 V1 EN-US (Equation 60)
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
IP14512-1 v7
7.7.1 Identification
M17106-1 v7
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Thermal overload protection, one
time constant, Celsius
LCPTTR 26
Thermal overload protection, one
time constant, Fahrenheit
LFPTTR 26
7.7.2 Application
M15283-3 v8
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.
Section 7 1MRK 511 358-UEN A
Current protection
142
Application manual
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