Hi all, 

Looking for some input/advice here on how best to work around this -  

I have a 3 phase Sunsynk inverter which provides all my power 99.7% of the year, I very very rarely use any utility power whatsoever. 

My connection fee for 3 phases is very expensive - I have the option to reduce to a single phase 63amp supply and save around R60k per year. 

I do have 3 phase aircons, but these are not essential and do not need run when the grid is the only input. 

If I made the move to a single phase -

A ) Still be able to provide a single phase input to my inverter to provide power in the unlikely event that I need the grid (I understand I am limited to the 63 amp supply and it'll only be for a single phase)

B ) Still be able to output 3 phases from my inverter to avoid me having to rewire my board - also due to aircons being 3 phase
 

Edited August 17, 20233 yr by spotity

Hi @spotityunfortunately as good as your planning is. The 3 phase inverter machine behaves like a 3 phase appliance. If only a single phase is present then the Sunsynk will be in Islanding mode. The inverter will still output 3 phase power but not be able to see the grid at all due to loss of 2 other phases. 

1 hour ago, Steve87 said:

The inverter will still output 3 phase power but not be able to see the grid at all due to loss of 2 other phases. 

That's right. You will continue to run in 3 phase island mode. You could however for emergency use wire in a manual 3 phase trow over switch to bypass the inverter. Connect the incoming single phase to all 3 phases of the switch. All single phase appliances would work, only the 3 phase aircons wouldn't.

Seems like such a thing called a rotary phase converter exists, which seems pretty interesting, and, possible to DIY (its pretty much 3-phase motor with some capacitors and drop-out relay) it seems.

@Beatyes this is possible, however, I think someone like @TaliaBcan comment on legality & certification of such. My humble uneducated guess is that a CoC cannot be valid for such an installation. But hey I'm not a expert on certification of such. 

 

2 hours ago, Steve87 said:

Hi @spotityunfortunately as good as your planning is. The 3 phase inverter machine behaves like a 3 phase appliance. If only a single phase is present then the Sunsynk will be in Islanding mode. The inverter will still output 3 phase power but not be able to see the grid at all due to loss of 2 other phases. 

Thanks @Steve87 makes sense. 

18 minutes ago, reapster said:

Seems like such a thing called a rotary phase converter exists, which seems pretty interesting, and, possible to DIY (its pretty much 3-phase motor with some capacitors and drop-out relay) it seems.

Interesting concept, would be interested to find out if anybody has done this successfully. 

1 hour ago, reapster said:

Seems like such a thing called a rotary phase converter exists, which seems pretty interesting,

It will be massive, noisy, and expensive, if it has enough power to run a house load, or significant portion thereof.

10 hours ago, spotity said:

Hi all, 

Looking for some input/advice here on how best to work around this -  

I have a 3 phase Sunsynk inverter which provides all my power 99.7% of the year, I very very rarely use any utility power whatsoever. 

My connection fee for 3 phases is very expensive - I have the option to reduce to a single phase 63amp supply and save around R60k per year. 

I do have 3 phase aircons, but these are not essential and do not need run when the grid is the only input. 

If I made the move to a single phase -

A ) Still be able to provide a single phase input to my inverter to provide power in the unlikely event that I need the grid (I understand I am limited to the 63 amp supply and it'll only be for a single phase)

B ) Still be able to output 3 phases from my inverter to avoid me having to rewire my board - also due to aircons being 3 phase
 

@spotityThe problem is that with your current 3ph supply your db board is wired for 3 inputs L1,L2 L3 +N. If moving from 3ph to single phase you need to bridge the 3 ac inputs into 1 single phase input with correct gauge wires. You now have a new single phase db board with a coc issued. You can not legally integrate single phase and 3 phase in one db board.Option 2  transfer all single Phase circuits to the New Single Phase Board. Your three phase loads will remain in the existing db board powered by the 3ph inverter.

18 hours ago, spotity said:

Thanks @Steve87 makes sense. 

Interesting concept, would be interested to find out if anybody has done this successfully. 

I will go into phase converters when i get a chance i have build several of these phase converters for clients that has 3ph woodworking machines with great success they are powerfull units. There are 2 types static converters and rotary converters where the latter is the most effiecient. I will do an explanation of working with some drawings.