pm750 meters voltage varing

[mcolston]

Got some weird behaviour on some existing meters on a site I'm upgrading to PME 8.

About 7 of them (All the same meter and all the same version – PM750) are “losing” one or other of the three phase to phase voltages – randomly and sometimes 2 of them – but and this is the kicker – the phase to N voltages are stable.

Do you think it is a meter issue or that there is some back feeding going on as there are some very big motors that have inverters on and do regen back to the grid.

The odd thing is that there are some other meters – also PM750’s but a different version – In an adjoining panel that don’t do it.

Any thoughts on what could be happening.

I've not checked with an old Avo meter yet - but a normal fluke doesn't seem to see an issue.

[mcolston]

I've swapped out one of the meters to a PM5110 and the voltages are now stable. Any logical reason why several meters would display the same issue?

It doesn't seem to have affected the kWh readings as we are seeing very similar results now compared to before.