Installation manual

UNIPOWER

Installation manual PQ Secure

4.4.6 HV 3-phase measurement with 3CT’s and 3PT’s (Line-to-line voltages)

Figure 14

The above wiring diagram is used for three-phase measurement in electricity networks with 3 CT´s

and 3 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). Always protect the voltage inputs with a 1A fuse in each conductor (red 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 PT+ I1+ = L1 CT+

U1- = L2 PT+ I1- = L1 CT- (Grounded)

U2+ = L2 PT+ I2+ = L2 CT+

U2- = L3 PT+ I2- = L2 CT- (Grounded)

U3+ = L3 PT+ I3+ = L3 CT+

U3- = L1 PT+ I3- = L3 CT- (Grounded)

Note: This configuration is normally used in medium voltage networks.