2.0
480
0.035
32 0.5
TD
t
V Vpickup
Vpickup
×
= -
æ ö
- >
× -
ç ÷
>
è ø
ANSIEQUATION2423 V1 EN-US (Equation 182)
The type C curve is described as:
3.0
480
0.035
32 0.5
TD
t
V Vpickup
Vpickup
×
= +
æ ö
- >
× -
ç ÷
>
è ø
ANSIEQUATION2421 V1 EN-US (Equation 183)
The customer programmable curve can be created as:
P
TD A
t D
V Vpickup
B C
Vpickup
×
= +
-
× -
æ ö
ç ÷
è ø
EQUATION1616 V1 EN-US (Equation 184)
When the denominator in the expression is equal to zero the time delay will be infinity. There will
be an undesired discontinuity. Therefore a tuning parameter
CrvSatn
is set to compensate for this
phenomenon. In the voltage interval
Vpickup
up to
Vpickup
· (1.0 +
CrvSatn
/100) the used voltage
will be:
Vpickup
· (1.0 +
CrvSatn
/100). If the programmable curve is used this parameter must be
calculated so that:
EQUATION1440 V1 EN-US (Equation 185)
The details of the different inverse time characteristics are shown in section "Inverse
characteristics".
TRIP signal issuing requires that the residual 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
some special 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, and is
not fulfilled again within a user defined reset time (
tReset1
and
tReset2
for the definite time and
tIReset1
and
tIReset2
for the inverse time) the corresponding PICKUP output is reset, after the
defined reset time has elapsed.
Here it should be noted that after leaving the hysteresis area, the PICKUP condition must be
fulfilled again and it is not sufficient for the signal to only return back to the hysteresis area. Also
notice that for the overvoltage function TOV reset time is constant and does not depend on the
voltage fluctuations during the drop-off period. However, there are three ways to reset the timer,
either the timer is reset instantaneously, or the timer value is frozen during the reset time, or the
timer value is linearly decreased during the reset time. See figure
340 and figure 341.
Section 9 1MRK 502 066-UUS B
Voltage protection
630
Technical manual
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