208 3ø to 240v 1ø Transformer for Sonnen

[MJRobinson]

Hello,

I am looking to add a Sonnen Energy storage system for some loads at a business that has 208v. Although you can take 2 legs and make 240v 1ø, the system won't work.

from Sonnen design team:
Although we can get 240V off of two hots from the 3 phase system, we would still need to have a transformer to make sure the power arriving to the Sonnen is in phase. We have had customers try the configuration you proposed in the past and the unit does not accept the power in this case.

1) What is the calculation for the transformer, the 240v side is 50A , (240 x 50/1000) = 12kVa. but we are going 3-Phase 208 to 1-Phase 240v. Looking for calculations on that.

2) Can someone point me to an article describing why we do it this way?

Thanks,

Mike

 

[kwired]

Hello,

I am looking to add a Sonnen Energy storage system for some loads at a business that has 208v. Although you can take 2 legs and make 240v 1ø, the system won't work.



1) What is the calculation for the transformer, the 240v side is 50A , (240 x 50/1000) = 12kVa. but we are going 3-Phase 208 to 1-Phase 240v. Looking for calculations on that.

2) Can someone point me to an article describing why we do it this way?

Thanks,

Mike

I take it you are trying to supply two phases and neutral feeder circuit supplied by 208/120 three phase system?

The phase angles are not the same on this as they are on single phase 120/240.

If you are actually taking all three phases and wanting to use them to supply a single phase output, you will probably need somthing that rectifies it to DC then inverts it back to AC single phase, and then still may need additional transformation if going from 208 to 240 which could be on input or output of the entire process.

 

[MJRobinson]

I take it you are trying to supply two phases and neutral feeder circuit supplied by 208/120 three phase system?

The phase angles are not the same on this as they are on single phase 120/240.

If you are actually taking all three phases and wanting to use them to supply a single phase output, you will probably need somthing that rectifies it to DC then inverts it back to AC single phase, and then still may need additional transformation if going from 208 to 240 which could be on input or output of the entire process.

Yes to your question and thanks.

 

[ggunn]

Hello,

I am looking to add a Sonnen Energy storage system for some loads at a business that has 208v. Although you can take 2 legs and make 240v 1ø...

Actually, no, you can't. Phase to phase voltage is 208V, not 240V. While each CCC is 120V to N, the phase angles are 120 degrees.

 

[jeremy.zinkofsky]

If i am understanding correctly, you have 208V, 3-Phase power available and you need to power a 240V/1-Phase load?

If so, you will need a boost transformer to accomplish this. Try using this link http://www.buckboostcalculator.com/index.cfm

 

[synchro]

I am looking to add a Sonnen Energy storage system for some loads at a business that has 208v. Although you can take 2 legs and make 240v 1ø, the system won't work.

1) What is the calculation for the transformer, the 240v side is 50A , (240 x 50/1000) = 12kVa. but we are going 3-Phase 208 to 1-Phase 240v. Looking for calculations on that.

What are the loads that you need to support? Are they 120V only, 208V single-phase, 208V three phase?
To get 120V/240V single-phase you could use a 208V to 120V/240V transformer like the one below fed by two lines of your 208V supply.

Low Voltage Distribution Transformer - Single Phase, 120/208/240/277 - 120/240V, 15kVA | T279747S | Acme Electric

Low Voltage Distribution Transformer - Single Phase, 120/208/240/277 - 120/240V, 15kVA

www.hubbell.com

https://hubbellcdn.com/technicaldrawing/T279747S.pdf

 

[winnie]

This is an energy storage system. Power has to flow in _two_ directions, from the grid tied system to the storage system, and back.

You can take 3 phase 208V and with appropriate transformers synthesize single phase center tap 240V. But going in the reverse direction those transformers will not regenerate the appropriate 3 phase angles.

You would need an energy storage system designed for 3 phase use.

-Jon

 

[MJRobinson]

Actually, no, you can't. Phase to phase voltage is 208V, not 240V. While each CCC is 120V to N, the phase angles are 120 degrees.

thanks

 

[MJRobinson]

What are the loads that you need to support? Are they 120V only, 208V single-phase, 208V three phase?
To get 120V/240V single-phase you could use a 208V to 120V/240V transformer like the one below fed by two lines of your 208V supply.

Low Voltage Distribution Transformer - Single Phase, 120/208/240/277 - 120/240V, 15kVA | T279747S | Acme Electric

Low Voltage Distribution Transformer - Single Phase, 120/208/240/277 - 120/240V, 15kVA

www.hubbell.com

https://hubbellcdn.com/technicaldrawing/T279747S.pdf

Thanks,

I am getting this quoted.

 

[MJRobinson]

This is an energy storage system. Power has to flow in _two_ directions, from the grid tied system to the storage system, and back.

You can take 3 phase 208V and with appropriate transformers synthesize single phase center tap 240V. But going in the reverse direction those transformers will not regenerate the appropriate 3 phase angles.

You would need an energy storage system designed for 3 phase use.

-Jon

Thanks,

This is will be a one-way back-up only feeding a critical loads panel.

 

[kwired]

Thanks,

This is will be a one-way back-up only feeding a critical loads panel.

Is it in any way parallel to the main supply? That is where not being in phase will a problem.

If it simply transfers when main power is lost it may still be something you can use, especially if all loads supplied are 120 volts. If there are any 208 volt loads they will see 240 when this backup kicks in.