ABB RES670 Technical Manual page 284

Section 9
Voltage protection
Voltage
VA
VB
VC
278
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:
CrvSatn
× - >
B C 0
100
EQUATION1435 V1 EN-US
The lowest voltage is always used for the inverse time delay integration. The details of
the different inverse time characteristics are shown in section
Figure 88: Voltage used for the inverse time characteristic integration
Trip signal issuing requires that the undervoltage 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 (TUV). 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 pickup for the
inverse time) the corresponding pickup output is reset. 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. For the undervoltage function the TUV 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: the timer is reset
instantaneously, the timer value is frozen during the reset time, or the timer value is
linearly decreased during the reset time. See figure
1MRK 511 408-UUS A
"Inverse characteristics".
IDMT Voltage
Time
ANSI12000186-1-en.vsd
89 and figure 90.
Phasor measurement unit RES670 2.2 ANSI
Technical manual
(Equation 53)