UNIPOWER
UP-2210R/P Hardware installation and configuration manual
4.4.11 HV 3-phase measurement with 2 CT’s and 3 PT’s (Line-to-line voltages)
Figure 20
The above wiring diagram is used for three-phase measurement in in public distribution networks
with 2 CT’s and 3 PT’s. The voltage channels of the unit are connected to the PT’s (normally 63 V
AC secondary to earth), for supplying line-to-line voltages, and current channels are connected to the
CT´s (normally 1 - 5 A AC secondary). Always protect the voltage inputs with a suitable fuse in
each conductor on the secondary side of the PT. Two current channels are measured and the third is
calculated by the measuring device. The connection for this type of measurement is as follows:
Channel: Measured object: Channel Measured object:
U1 = L1 PT+ I1+ = L1 CT+
U2 = L2 PT+ I1- = L1 CT-
U3 = L3 PT+ I3+ = L3 CT+
Ref = L1 PT-, L2 PT-, L3 PT- I3- = L3 CT-
Note: If this method is used, the meter will automatically calculate the current I2. This
configuration is normally used in medium voltage networks.
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