frederickjh
New Member
- Joined
- Jan 14, 2022
- Messages
- 8
I can't figure out why bonding neutral center tap of transformer to ground would cause overload fault in inverter, unless one of the inverter Line outputs was grounded.
I don't easily find the manual for it to review; they have so many models. I only see a few details in the listing.
PIP 8048MAX 8000Watt 48V Off Grid Inverter | MPP Solar
NO LOCAL STOCK Status indication with RGB breathing lights Built-in WiFI for remote mobile monitoring (Android and IOS is available) Supports USB On-the-Go function Reserved communication port for BMS (RS485, CAN-BUS or RS232) Replaceable fan design for ease of maintenance Battery independent...mppsolar.com.au
Have you checked that all wires have correct voltage relative to each other and to ground?
With a 230V isolated inverter, you should be able to ground either line, or the center tap of a transformer.
With a source that already has one end grounded, like 230V utility line & neutral, an auto-transformer producing 115V center tap couldn't have the center-tap grounded. In that case, an autotransformer would need and extra winding and tap, for +230V, +115V, Neutral, -115V
I found this post because I have a similar situation. I have the MPP 8048MAX inverter and a 5000VA torrid center tap transformer, which I believe is electrically similar to the SolarEdge SE5000 Autotransformer.
Hedges is almost correct in his guess that one of the Line inputs is grounded . . .
ibkickinit says
this is incorrect. The MPP 8048MAX is not a USA inverter. If you look at the inverter and manual on page 6 (8th page in the PDF) you will see the terminals for both AC line in and AC line out are labeled L, N, and ground. The neutral is internally connected to ground. So, with the ground bonded in the circuit breaker box the inverter would send 230 VAC to ground and the transformer center tap would send 115 VAC to ground via the neutral bond. Thus the F05 error from the 4048MAX."50-Amp 2-pole breaker for L1/L2 coming from the inverter into the panel, . . ."
The neutral on the AC input is not connected to ground on the MPP 8048MAX, but the neutral on the AC output is. This unit is designed for Europe and other parts of the world that use 220 VAC at the outlet and then what is called the second line output in the USA is a neutral as there is no 110VAC nor line 2, just line and neutral which are normally wired with brown and blue wires respectively (one can see this internally on the 8048MAX.
So measuring continuity across the terminals with the 8048MAX off, you will see that the neutral and the ground are bounded together and have continuity. With the unit on, from the terminals labeled, L to N 230VAC, L to ground 230VAC, Neutral to Ground 0 VAC.
However this still leaves me with the question of how to properly ground this setup. Currently I have the ground wire from the inverter not connected anywhere.
I believe that ibkickinit has his inverter and transformer grounds connected to the ground bus in the circuit box but his neutrals are not bonded to ground as he has the bond disconnected, which I believe leaves them grounded.
Any ideas on how to correctly wire this with proper grounding would be appreciated.