Converting Delta into Wye?

[davedottcom]

In an existing situation (3-phase 240V Delta service w/ 208 hi-leg)...

How difficult is it for the utility Co. to reconfigure the service to a 3-phase 240V Wye (No hi-leg)? Also would any alterations be necessary to the existing service? (Other than removing the orange tape)

 

[frenchelectrican]

It can be done but you will not like the flavour at all.

It used to be common voltage in Europe 230Y127 system so therefore the line to netual will be pretty high I expect to be reading in 132 volt range { L-N }

However the normal pratice is go with 208Y120 which it is far much common and The POCO can use the stanard transfomer cans instead of use specal order item.

Any reason if some equiment do not work very well or not listed to run on 208 v L-L then use the B/B {buck / boost } transfomer to upstep either 32 or 36 volts depending on the supply voltage.

And you have to keep in your mind about single phase load that may catch you off gaurd on this one.

Merci,Marc

 

[jim dungar]

In an existing situation (3-phase 240V Delta service w/ 208 hi-leg)...

How difficult is it for the utility Co. to reconfigure the service to a 3-phase 240V Wye (No hi-leg)? Also would any alterations be necessary to the existing service? (Other than removing the orange tape)

I know of no utility that provides a 240Y/138 service. Did you mean a 208Y/120 one?

There is not much work for the utility except to change the transformers and the meter. Inside you would not even need to remove the orange tape, as that color is not restricted to use only on "high legs". Of course any thing in your facility that is rated as 240V will now only see 208V.

 

[davedottcom]

Ok, no 240V 3-phase without a high leg... that stinks.

I'll have to look into the 240V loads that are present.

Thanks guys!

 

[jim dungar]

Ok, no 240V 3-phase without a high leg... that stinks.

I'll have to look into the 240V loads that are present.

Thanks guys!

I am still confused.
You have 240/120 3PH 4W (a center tapped delta with a high leg).

What are you trying to accomplish?
Do you want 240V 3PH 3W (a delta w/o a high leg)? If so, why?
Or do you want 208Y/120 3PH 4W?

 

[davedottcom]

I am still confused.
You have 240/120 3PH 4W (a center tapped delta with a high leg).

What are you trying to accomplish?
Do you want 240V 3PH 3W (a delta w/o a high leg)? If so, why?
Or do you want 208Y/120 3PH 4W?

Sorry for the confusion, I never explained what the situation was. Here goes... I have (5) 240 or 208 Single Phase Solar PV inverters that are not compatable with a 208 high leg. I need a 3-phase service that is 120V on each phase to Ground and either 208 or 240 volts from phase to phase. I would prefer 240 Volts instead of 208 because of the existing 240V HVAC loads.

I'm thinking that a seperate (New) 208 Service may be the best option at this point. The company purchased all of the solar equipment long before I ever got involved. After talking to the Inverter Manufacturer I realized "We've got a problem!"

The inverters must be connected to all 3 phases per NEC so not to create an unbalanced load...

My customer is talking with the POCO to see what they can or will do.

 

[jim dungar]

Sorry for the confusion, I never explained what the situation was. Here goes... I have (5) 240 or 208 Single Phase Solar PV inverters that are not compatable with a 208 high leg. I need a 3-phase service that is 120V on each phase to Ground and either 208 or 240 volts from phase to phase. I would prefer 240 Volts instead of 208 because of the existing 240V HVAC loads.

I'm thinking that a seperate (New) 208 Service may be the best option at this point. The company purchased all of the solar equipment long before I ever got involved. After talking to the Inverter Manufacturer I realized "We've got a problem!"

The inverters must be connected to all 3 phases per NEC so not to create an unbalanced load...

My customer is talking with the POCO to see what they can or will do.

The only system you can get for 120V L-N on all three phase conductors is 208Y/120.

240V heaters run at 208V just put out less heat (so things like duct heaters and water heaters just take longer to reach temperature). If you have some motors that are not dual rated 208/240V, or fussy 240V electronics, you could add a buck-boost transformer as needed to bring the 208V closer to 240V.

 

[davedottcom]

The only system you can get for 120V L-N on all three phase conductors is 208Y/120.

240V heaters run at 208V just put out less heat (so things like duct heaters and water heaters just take longer to reach temperature). If you have some motors that are not dual rated 208/240V, or fussy 240V electronics, you could add a buck-boost transformer as needed to bring the 208V closer to 240V.

10-4 :smile:

 

[charlie]

Talking with the serving electric utility is best. We will charge for the work of replacing the configuration of the voltage since the transformers will have to be replaced. The metering is fine if it the newer electronic meter. We would also charge for setting an additional pole and hanging a new bank for a second voltage. If you were dealing with us, it would be best to install a separately derived system for your Solar PV inverters to feed into.

 

[LarryFine]

Dave, just some things to keep in mind:

1. The 120/240v part of your equipment and loads are exactly the same thing as a simple 120/240v 1-ph system, exactly like the service in your house.

2. Only 3-ph 240v and line-to-line 1-ph 240v loads will (should) be connected to the high leg; any load with a neutral connection will (should) not be.

3. You will need to re-distribute your line-to-neutral loads among the three line conductors; a high-leg service more heavily loads the 120/240v lines.

4. You will likely also have to re-distribute your line-to-line loads. As has already been stated, most of these loads are 208v compatible, but be sure to check.

 

[acrwc10]

Talking with the serving electric utility is best. We will charge for the work of replacing the configuration of the voltage since the transformers will have to be replaced. The metering is fine if it the newer electronic meter. We would also charge for setting an additional pole and hanging a new bank for a second voltage. If you were dealing with us, it would be best to install a separately derived system for your Solar PV inverters to feed into.

I would bet this is the cheapest way to go. You would also wide up with a smaller transformer for the PV to feed into as it would be sized to the PV system and not the over all service size.