Ref 2 x Quattro 120VAC in stacked configuration with autotransformer on a boat. Shore power is usually 120 degrees phase angle, generator is 180 degrees. What is the setting to allow either to operate. Also what is the significance of the 240 degree phase angle - electrically this is the same as 120 degrees…?
The inverters will synchronise to the incoming.
Since they are different you may see overloads on connect and disconnect since you can only choose one in config (and probably the one you loads need)
Robert, you can configure the phase angle in VEbus system configurator. You would likely want to choose two phase 180° with “floating - return to phase” configured for L2. Note that the inverters will sync to one or the other and output the same phase rotation as the AC input.
The autotransformer is NOT going to like the 120° phase rotation coming from the Quattros. It’ll make a helluva noise and it’s not advisable to run it that way. You might find you are better off leaving L2 fixed at 180° and disable the “switch as group” option for the shore power AC input. This will let you still use the AT when connected to shore power, but will only have one Quattro charging batteries when connected to shore power.
I hope this helps.
Thank you, this is great info. We also found that the master had to be set to L1 for some reason. I have a question though - the AT is receiving 2-wire 208VAC, essentially a single phase input with no neutral, so there is no phase angle to worry about surely?
No, when you are connected to shore power you are connected to two phases. Just because you don’t have a neutral doesn’t mean it’s single phase. A 208/120V three phase wye system has a neutral so you can get 120V neutral-to-phase for your boat. Without the neutral you ONLY have 208V phase-to-phase. And those phases have 120° phase rotation. Your AT is not going to like that.
We think we have a handle on it now, thanks for your input. However we run many single-phase motors and transformers on the nominal 208VAC derived from L1-L2 with no neutral. The resultant voltage and current is a single sinusoidal waveform, and electrically this is the same as a single-phase supply, so we are not seeing any issues with the AT.