PAT tester doing odd things when solar generating

[tonyshouse]

They have noticed some strange readings when doing their electrical PAT testing,  also only seem to be evident when the PV are generating.

 

He wondered whether the PV could be the cause, and also wondered whether this may have any relationship to/bearing on the export meter issue that we thought needed looking at.

 

any opinions, the PV is grid connected , 

[ProDave]

What sort of strange readings?

 

I  had to do a repair on a small grid tie inverter and when testing it after the repair I was surprised to find it generated it's power in bursts, the opposite of how an immersion heater dump controller sends power to the immersion in bursts.  I don't know if the larger, better inverters also do this. 

 

 

[SteamyTea]

Isn't PAT for portable appliances, not fixed ones.

Are they testing the PV, or things plugged into it?

Not sure you need to have things 'plugged into the mains' to PAT them.

[tonyshouse]

I think they plug the PAT tester in to a normal socket near the inverter but on its own circuit from a distribution board, when testing appliances it gives strange readings when the solar is generating 50kWp system into same boardv

[SteamyTea]

1 hour ago, tonyshouse said:

I think they plug the PAT tester in to a normal socket near the inverter

Ah right, then it could well give a strange reading.

[tonyshouse]

Why? 

[ProDave]

33 minutes ago, tonyshouse said:

Why? 

If it's poorly designed and it's power supply does strange things if there is a bit of "noise" on the supply.

[TonyT]

Maybe because the PV is pushing a higher voltage than the normal mains voltage for it to export to the grid.

 

 

Edited November 12, 2020 by TonyT

[SteamyTea]

1 hour ago, TonyT said:

Maybe because the PV is pushing a higher voltage than the normal mains voltage for it to export to the grid.

If the grid voltage is at the upper limit, the inverter will have to disconnect or try its best to limit the voltage.  It may do this by pulsing, which is only turning off and on again, quickly.

 

[tonyshouse]

Fault on ring main, still there with solar off, they told us wrong