t
TD
V Vpickup
Vpickup
=
⋅
⋅
− >
>
−
−
480
32 0 5
0 035
.
.
ANSIEQUATION2287 V2 EN (Equation 32)
The type C curve is described as:
t
TD
V Vpickup
Vpickup
=
⋅
⋅
− >
>
−
+
480
32 0 5
0 035
.
.
ANSIEQUATION2288 V2 EN (Equation 33)
The highest phase (or phase-to-phase) voltage is always used for the inverse time delay
integration, see Figure 53. The details of the different inverse time characteristics are
shown in section "Inverse time characteristics"
en05000016_ansi.vsd
Voltage
Inverse Time Voltage
Time
VA
VB
VC
ANSI05000016 V1 EN
Figure 53: Voltage used for the inverse time characteristic integration
A TRIP requires that the overvoltage condition continues for at least the user set time
delay. This time delay is set by the parameter t1 and t2 for definite time mode (DT) and
by selected voltage level dependent time curves for the inverse time mode (TOV). If
the PICKUP condition, with respect to the measured voltage ceases during the delay
time, the corresponding PICKUP output is reset.
Section 8 1MRK 505 277-UUS C
Voltage protection
134
Technical Manual
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