816LE008146B
Measurement functions
6.2 Measurements in real-time
The sentinel Energy trip unit provides the following basic electrical value measurements in
real-time:
- Current for each phase and neutral (on 4-pole version)
- IG Ground fault current (resulting from 3 or 4 currents from active conductors)
- Voltages between phases and between phase and neutral on 3, 4 poles or 3 poles + ENVA
- Indication of the rotary field direction
- Network frequency.
In addition, the sentinel Energy trip unit calculates the following associated electrical values in
real-time (every second):
Electrical variable Symbol used 3-pole
version
3-pole
version +
ENVA
4-pole
version
RMS current of phases or neutral I1, I2, I3, IN
■ ■ ■
RMS earth current (three-phase
system with neutral)
IG
-
-
■
RMS earth current (three-phase
system without neutral)
IG
■ ■
-
RMS voltage V1N, V2N, V3N
-
■ ■
RMS voltage U12, U23, U31
■ ■ ■
Rotary field 1,2,3; 1,3,2
■ ■ ■
Frequency F
■ ■ ■
Electrical variable Value calculation 3-pole
version
4-pole
version
Average RMS current
I
average
=
I
1 +
I
2 +
I
3
3
■ ■
Maximum instantaneous RMS cur-
rent with neutral
-
■
Maximum instantaneous RMS cur-
rent without neutral
■
-
Minimum instantaneous RMS cur-
rent
■ ■
Average Ph-N RMS voltage
V
average
=
V
1N +
V
2N +
V
3N
3
-
■
Maximum Ph-N RMS voltage
-
■
Minimum Ph-N RMS voltage
-
■
Average Ph-Ph RMS voltage
U
average
=
U
12 +
U
23 +
U
31
3
■ ■
Maximum Ph-Ph RMS voltage
■ ■
Minimum Ph-Ph RMS voltage
■ ■