How is the meter itself grounded for ring type meter sockets

[electrofelon]

Basic question: which if any meters require a grounded conductor for voltage reference in order to properly do the metering?

Obviously for currents, it's enough to monitor all but one of the circuit conductors, as the current on the unmonitored conductor will then be determined by the fact the sum of all the currents is zero.

Cheers, Wayne

Single phase 120/208 is an example is it not?

 

[electrofelon]

I think nearly every 120/208 and 277/480 three phase wye meter takes a neutral connection, but I don't think it needs it to be blondel compliant right?

 

[kwired]

Single phase 120/208 is an example is it not?

They don't take neutral current reading though it is only a voltage reference.

 

[electrofelon]

They don't take neutral current reading though it is only a voltage reference.

Right, and that is what Wayne asked.

 

[jaggedben]

I don't think form 2S normally take a neutral voltage reading at all. In other words they are actually not Blondel compliant. (Unless it's that tab under the ring but that seems like a terrible way to do that, I very much doubt it.)

 

[Hv&Lv]

Basic question: which if any meters require a grounded conductor for voltage reference in order to properly do the metering?

Obviously for currents, it's enough to monitor all but one of the circuit conductors, as the current on the unmonitored conductor will then be determined by the fact the sum of all the currents is zero.

Cheers, Wayne

3S, 9S, 12S, 16S, 25S,
Others that aren't popular any longer.
For our CT metering, 3S or 9S is all we use.
What's great about the 9S is the versatility.
Say you have an open delta service. You want to drop the three phase and go to a single phase service.
We simply pull the fuse and disconnect the jumpers on the power pot.
The 9S will meter this single phase service perfectly.

The power calculation for this scenario is
Vab/2 * [Ia cos (θa - 30) + Ib cos (θb + 30)] + Vcn * Ic cos θc
Assumes all 3-phase voltages are balanced
Vcn = SQRT(Vcb² - Vbn²) & Van = Vbn = Vab/2
Given Vcn is a term on it’s own in the calculation, whether there is voltage or not, the
calculation for the A & B phase is unaffected.