ABB ret650, Technical Manual

Page: 160 / 670

8.3.6 Monitored data
Table 83: EFPIOC Monitored data
Name Type Values (Range) Unit Description
IN REAL - A Residual current
8.3.7 Operation principle
The sampled analog residual currents are pre-processed in a discrete Fourier filter
(DFT) block. From the fundamental frequency components of the residual current, as
well as from the sample values the equivalent RMS value is derived. This current
value is fed to the Instantaneous residual overcurrent protection (EFPIOC). In a
comparator the RMS value is compared to the set operation current value of the
function (
IN>> ). If the residual current is larger than the set operation current a signal
from the comparator is set to true. This signal will, without delay, activate the output
signal TRIP.
8.3.8 Technical data
Table 84: EFPIOC technical data
Function Range or value Accuracy
Operate current (1-2500)% of lBase
± 1.0% of I
r
at I £ I
r
± 1.0% of I at I > I
r
Reset ratio > 95% -
Operate time 20 ms typically at 0 to 2 x I
set
-
Reset time 30 ms typically at 2 to 0 x I
set
-
Critical impulse time 10 ms typically at 0 to 2 x I
set
-
Operate time 10 ms typically at 0 to 5x I
set
-
Reset time 40 ms typically at 5 to 0x I
set
-
Critical impulse time 2 ms typically at 0 to 5 x I
set
-
Dynamic overreach < 5% at
t
= 100 ms -
8.4 Four step residual overcurrent protection, zero,
negative sequence direction EF4PTOC
Section 8
1MRK 504 135-UEN A
Current protection
154
Technical manual