Jump to content

3 Phase Inverters/Installations


CJW

Recommended Posts

First off I want to state that although I successfully installed and operate a small 900w 12 volt system, I am a newbie to solar installations in as far as inverters and AC power is concerned.

I am considering an installation on a farm where 3 phase power is available in the house with (according to my electrician) 60 or 80 Amps available per phase.  These 3 phases is currently distributed across all the loads within the db and there is no appliance or tool that uses 3-phase power that is powered through the circuitry of the dwelling. The main idea for now is to use the installation purely as a back-up system to the unreliable (complete outages or "phase-drops") Eskom supply. The back-up is only needed for "critical loads" such as lights, fans, refrigeration, security installations etc. and my guess was that 5 - 6kW would be ample. Geysers, stove, aircons, kettle, swimmingpool pump etc would be excluded from the back-up system. Solar installation will only follow in a couple of years.

I initially opted to go for the 10kW Infini, but with all the negative comments I am a bit hesitent especially since my Eskom supply is definately not up to scratch with suspected fluctuating voltages which might damage the Infini. I also considered a Victron inverter (big fan), but it would seem that one single unit with 3-phase capability is unavailable. I simply cannot afford 3 Victron inverters for a 3-phase installation, bearing in mind that each inverter will need it's own battery/set of batteries.

As I understand another option is to use a single phase inverter on one of the supplied phases to power the inverter and critical loads and use the other two phases for the non-critical loads.

What are the pitfalls when using this latter type of installation, alternatively what other 3-phase inverters might be considered.

Link to comment
Share on other sites

31 minutes ago, CJW said:

... , bearing in mind that each inverter will need it's own battery/set of batteries.

Can only comment on the above, nope, not needed, all 3 are on one bank.

What do you think 3 of them would cost? If you want to go Victron, drop me a PM. Can point you to where to get them from.

Link to comment
Share on other sites

14 minutes ago, The Terrible Triplett said:

Can only comment on the above, nope, not needed, all 3 are on one bank.

What do you think 3 of them would cost? If you want to go Victron, drop me a PM. Can point you to where to get them from.

"One bank", now that's an eye opener. The added benefit is that if one phase fails the other two inverters on the remaining two phases will automatically recharge the battery which also supply the inverter on the failed phase.

 

Will drop you a PM when ready, thank you

Link to comment
Share on other sites

1 minute ago, CJW said:

... remaining two phases will automatically recharge the battery which also supply the inverter on the failed phase.

That is assuming you have no panels otherwise the MPPT'/s will keep on charging the batteries whether the inverters are on or not. 

Link to comment
Share on other sites

12 minutes ago, CJW said:

The added benefit is that if one phase fails the other two inverters on the remaining two phases will automatically recharge the battery

I'm not so sure what if this will happen, as far as i know, the 120degree offset on each phase requires all three phases to be active in order to get a working three phase system. If you have no 3 phase equipment you can always run an inverter off each phase as if it is single phase, in which case if one phase goes down the other three will continue as per usual.

12 minutes ago, CJW said:

One bank", now that's an eye opener.

On victron documentation they  stipulate that you should not run a bank for each inverter but should rather have one bank across all three inverters. So yeah... one bank only which makes things a lot easier actually

Edited by stoic
Link to comment
Share on other sites

6 minutes ago, stoic said:

as far as i know, the 120degree offset on each phase requires all three phases to be active in order to get a working three phase system

That's only if you need a rotating magnetic field, as in a three-phase induction motor. Or if you otherwise need the phase to phase voltages. The OP stated that all his loads are single phase. So I believe (without having much experience here) that there is no problem if one phase drops out.

Link to comment
Share on other sites

2 minutes ago, Coulomb said:

That's only if you need a rotating magnetic field, as in a three-phase induction motor. Or if you otherwise need the phase to phase voltages. The OP stated that all his loads are single phase. So I believe (without having much experience here) that there is no problem if one phase drops out.

yup ... i updated the answer as soon as i saw it.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...