Dranetz PX5 Connections

[tkb]

I connect Dranetz PX5 meters to monitor customer power usage from time to time and I am confused on the connection for a 3 wire Wye connection without a neutral.

When I have a neutral available and used, I connect the amp probe and the neutral voltage connection as in the page 3 Phase 4 Wire Wye. This page does not show the neutral amp probe, but I connect it when the neutral is used.

Some times there is a neutral available but it is not being used by the load being monitored so I make the connection as shown on the page 3 Phase 4 Wire Wye.

My question is, When I have a 3 Phase Wye system that does not have the neutral available, how should I connect the meter.

There is a drawing for a 3 Phase (Floating or Grounded) Delta system.
Is this how I should connect the meter or should I connect it like the 3 Phase 4 Wire Wye and connect the neutral and ground voltage probes to ground?

View attachment 3304

 

[ATSman]

I connect Dranetz PX5 meters to monitor customer power usage from time to time and I am confused on the connection for a 3 wire Wye connection without a neutral.

When I have a neutral available and used, I connect the amp probe and the neutral voltage connection as in the page 3 Phase 4 Wire Wye. This page does not show the neutral amp probe, but I connect it when the neutral is used.

Some times there is a neutral available but it is not being used by the load being monitored so I make the connection as shown on the page 3 Phase 4 Wire Wye.

My question is, When I have a 3 Phase Wye system that does not have the neutral available, how should I connect the meter.

There is a drawing for a 3 Phase (Floating or Grounded) Delta system.
Is this how I should connect the meter or should I connect it like the 3 Phase 4 Wire Wye and connect the neutral and ground voltage probes to ground?

View attachment 3304

You would connect it as shown for a 3 Phase 4 Wire Wye. The reason being
is that it is still a grounded system (even though the neutral is not used) and if the load (motor or delta xfmr winding) sees a ground fault then
the ground current will flow from the fault through the ground (conduit, enclosure) back to the point where the neutral is grounded to the Xo of the supply transformer. This is true if the Dranetz meter is used for troubleshooting an electrical disturbance. If it is used just to record total power used then either connection will work.

Tony