UNIPOWER
UP-2210R/P Hardware installation and configuration manual
36
4.6
Recommended practices
Below, recommendations are given for a number of common network situations.
4.6.1
Impedance grounded 3-wire systems
Typical examples: MV distribution networks in a 3-phase, 3-wire network without neutral conductor
impedance grounding (Petersen coil with/without resistor) is common. Figure 28 shows the
secondary side of the transformer and the grounding impedance.
When an earth fault occurs the transformer neutral point voltage U
n
rises. Measuring this voltage is a
good indicator of earth faults and can be used to track them.
Connect your UP-2210 to measure
line-to-line voltages U1-U3
and phase currents
I1-I3
according
to one of the sections 4.4.3, 4.4.4, 4.4.5, and 4.4.6 depending on how many PT/CT there are.
Connect channel
U4
to measure the transformer neutral point voltage U
n
.
Channel
I4
is normally not used. Connect it to ground.
4.6.2
Effectively (directly) grounded 3-wire systems
Typical examples: HV distribution and transmission networks.
HV networks are 3-phase, 3-wire networks without neutral conductor. Direct grounding is common
here.
Connect your UP-2210 to measure
line-line voltages U1-U3
and phase currents
I1-I3
according to
one of the sections 4.4.9, 4.4.10, 4.4.11 and 4.4.12 depending on how many PT/CT there are.
Channels
U4
and
I4
are normally not used. Connect them to ground.
Un
Figure 28
