UNIPOWER
UP-2210R/P Hardware installation and configuration manual
27
4.4.10
HV 3-phase measurement with 3 CT’s and 2 PT’s (Line-to-line voltages)
Figure 19
The above wiring diagram is used for three-phase measurement in public distribution networks with
3 CT´s and 2 PT’s. The voltage channels of the unit are connected to PT’s (normally 110 V AC
secondary), for supplying line-to-line voltages, and current channels are connected to CT’s (normally
1 - 5 A AC secondary). Two voltage channels are measured and the third is calculated in the
measuring device.
Always
protect the voltage inputs with a suitable fuse in each conductor on the
secondary side of the PT. The connection for this type of measurement is as follows:
Channel:
Measured object:
Channel:
Measured object:
U1
=
L1-L2 PT+
I1+
=
L1 CT+
U2
=
L2-L3 PT-
I1-
=
L1 CT-
Ref =
L1-L2 PT-, L2-L3 PT+
I2+
=
L2 CT+
I2-
=
L2 CT-
I3+
=
L3 CT+
I3-
=
L3 CT-
Note: If this method is used, the meter will automatically calculate the third line-to-line
voltage (U
L3 - L1
). This configuration is normally used in medium voltage networks.
