Measurement Computing WavePort 312P rev.1.0 - Manual (Page 39)

PowerVista/312 User’s Manual Device Configuration 4-5
4.1.4 Three Phase UnGrounded Wye
System Configuration PT Connection: Wye or Delta
The three phase Ungrounded Wye system can be measured using two methods which will yield identical three
phase answers. Since there is a neutral connection available, per phase measurements similar to the Grounded
Wye can be made, and supply valuable per phase information. However, since no ground currents are able to
flow in this system, a Delta connection can be made as well. Note that using a Delta PT connection will result in
no per phase information. By definition, the Two Wattmeter Method only calculates a total three phase power
value. For a Delta connected PT specified in EasyPower Measure, the per phase values are calculated simply as
the total three phase value from the Two Wattmeter Method, divided by three. Figures 4-3 and 4-4 illustrate
proper external connections for both Wye and Delta PT selections for an Ungrounded Wye system.
Figure 4-3. Connection Arrangement for Delta or Wye PT Selection for Ungrounded Wye System.
Figure 4-4. Connection Arrangement for Delta PT Selection Only for Ungrounded Wye.
Safety ground should be connected to the nearest bonafied system ground point.