Using two legs off a Delta Three Phase 230 volt Panel

[powerplay]

Hello All,

To provide power for a Three Phase DIshwasher and Three Phase Oven, we are planning to bring a combination Subpanel into the Suite with only 120/240 volts Single Phase.

Aside from checking for Ground Fault Detection Device and difficulty to balance the power of a single phase 240 volt 30 amp Expresso Machine, are there other concerns if ungrounded ? I will confirm details after arranging access for Monday.

Thank you for any insight !

 

[ptonsparky]

Lots of concerns for ungrounded, but Monday may shed more light on the project.

Need some details.

 

[powerplay]

I am only aware of the Delta 230 volts for heater or motor loads to assure uninterrupted power and manage a shutdown if a fault occurs, but to install a 120/208 Wye I presume it would be better, but any concerns when Building has grounded Single Phase 120/240 volts to connect for the Wye Secondary off the Delta source ?

If we took 230 volts Single Phase for an Expresso machine would it mess up the voltage balance on the Three Phase Delta ?

Would that affect the ground fault lights ?

Thanks again for any feedback !

 

[ptonsparky]

You have an ungrounded Delta service for machinery. From that service you have a single phase 120/240 transformer with properly installed GES.

The added single phase load may cause some voltage imbalance but would dependent on the SE size.

IMO, It should not affect the ground fault lights but I have only seen two of those systems in 50 years.

 

[jim dungar]

Would that affect the ground fault lights ?

Your description of what you have and what you want is hard to follow.

But, ground faults only react to grounds on the system not to imbalanced loading.

How much of an imbalance is your single phase espresso machine causing?
Its impact will depend on the stiffness of the source, as ptonsparky said. Utilities are all three phase sources, but they feed alot of single phase loads.

 

[powerplay]

You have an ungrounded Delta service for machinery. From that service you have a single phase 120/240 transformer with properly installed GES.

The added single phase load may cause some voltage imbalance but would dependent on the SE size.

IMO, It should not affect the ground fault lights but I have only seen two of those systems in 50 years.

You have an ungrounded Delta service for machinery. From that service you have a single phase 120/240 transformer with properly installed GES.

The added single phase load may cause some voltage imbalance but would dependent on the SE size.

IMO, It should not affect the ground fault lights but I have only seen two of those systems in 50 years.

I am not familiar with “SE” size, but presume the Delta should be for only balanced three phase loads, and is not recommended for single phase loads to ensure less voltage fluctuation ?

I presumed that indicator lights would not be affected aside from a line to line fault, but wondered if with a possible floating voltage reference if there is an audible alerting device if it would go off. I had encountered it a few times and wondered why I was getting odd readings to ground.

 

[powerplay]

Your description of what you have is have and what you want is hard to follow.

But, ground faults only react to grounds on the system not to imbalanced loading.

How much of an imbalance is your single phase espresso machine causing?
Its impact will depend on the stiffness of the source, as ptonsparky said. Utilities are all three phase sources, but they feed another of single phase loads.

I am referring to finding a Three Phase 230 volt System in Main Electrical Room for a Panel within a Building Suite that used to be for machinery. Monday we hope to be able arrange access with the tenant to bring the power on a separate meter for a small Bakery/Coffee Shop for their Three Phase Oven, a Three Phase Dishwasher, and now they are considering adding a coffee machine that is Single Phase 240 volt 30 amps.

If unbalanced loads may create an voltage unbalance on the ungrounded system we will add only the balanced three phase loads (oven 12.5kw, dishwasher 12.5kw ) to save cost on installation than add an Wye System if not necessary for safety, and add the coffee machine onto the existing 120/240 Single Phase Panel.

 

[jim dungar]

I had encountered it a few times and wondered why I was getting odd readings to ground.

If you have ground indicating lights, you have an ungrounded system (grounded systems use other schemes for ground fault detection).
An ungrounded system will give L-G voltages readings that vary based on loading and coupling capacitance. Do not trust any L-G readings on ungrounded systems.

 

[jim dungar]

onto the existing 120/240 Single Phase Panel.

What existing single phase? I thought you said you had a utility provided ungrounded delta 240V source?

240/120V 3phase 4wire center tapped system can be provided by both closed delta and open delta transformer configurations. A lot of industry slang seems to indicate 120/240V center tapped systems are always open delta and straight 240V are closed delta, but this is not the case.

As long as you keep your single phase loading on the 120/240V lines (i.e. the A and C phases), you should not have any severe voltage imbalance assuming the utility has sized their transformer correctly.

 

[curt swartz]

This is a very confusing thread. It doesn't seem like the OP is an electrical professional so they really need to get a qualified EC or EE involved.

Single Phase, Three Phase, Wye, Delta. In addition to 240V, 208V and they keep throwing 230V in.

They need to start with the available service to the building then work their way to the utilization equipment to figure out what is needed.

 

[powerplay]

This is a very confusing thread. It doesn't seem like the OP is an electrical professional so they really need to get a qualified EC or EE involved.

Single Phase, Three Phase, Wye, Delta. In addition to 240V, 208V and they keep throwing 230V in.

They need to start with the available service to the building then work their way to the utilization equipment to figure out what is needed.

I am not an Engineer although do hire one that likes our work and requested I help him verify conductors on Drawings to redesign electrical for 480 volt transformers to relocate to expand a film studio being designed for an Architect to soundproof fir filming, but have been an electrician since 1996 and a Contractor for 20 years on referral not advertising and simply reflecting the available voltages that are written on the Lamacoid labels in the building indicating what is present, and on the equipment labels needing power to be accurate in details. We do have nominal voltages for calculations but not always the voltages available.

Single Phase is the 120/240 volts labelled on one of two Main Disconnects and is an available electrical System from a Single Transformer off one leg of the Three Phase Primary Line.

In the same Main Electrical Room from a Bank of Pole Mount Transformers on another Pole for 230 volt Delta Three Phase supply, which apparently can fluctuate voltages when not balanced, so considering installing a Delta- Wye Transformer to create a center tap and possibly a safer supply for a bakery.

 

[curt swartz]

I am not an Engineer although do hire one that likes our work and requested I help him verify conductors on Drawings to redesign electrical for 480 volt transformers to relocate to expand a film studio being designed for an Architect to soundproof fir filming, but have been an electrician since 1996 and a Contractor for 20 years on referral not advertising and simply reflecting the available voltages that are written on the Lamacoid labels in the building indicating what is present, and on the equipment labels needing power to be accurate in details. We do have nominal voltages for calculations but not always the voltages available.

Single Phase is the 120/240 volts labelled on one of two Main Disconnects and is an available electrical System from a Single Transformer off one leg of the Three Phase Primary Line.

In the same Main Electrical Room from a Bank of Pole Mount Transformers on another Pole for 230 volt Delta Three Phase supply, which apparently can fluctuate voltages when not balanced, so considering installing a Delta- Wye Transformer to create a center tap and possibly a safer supply for a bakery.

230 volts is not a standard supply voltage in the US. A typically Delta supply is 240 volt 4-W. Unless this is a heavy industrial building it unlikely you have a 3-wire un-grounded supply.

The voltage should not be fluctuating unless you are really overloading the transformers. Most 4-wire Delta systems are open Delta designed for most of the load on the single phase mid-point grounded winding with minimal 3 phase load. If the building has a large 3 phase load the supply will be a closed Delta.

 

[powerplay]

What existing single phase? I thought you said you had a utility provided ungrounded delta 240V source?

240/120V 3phase 4wire center tapped system can be provided by both closed delta and open delta transformer configurations. A lot of industry slang seems to indicate 120/240V center tapped systems are always open delta and straight 240V are closed delta, but this is not the case.

As long as you keep your single phase loading on the 120/240V lines (i.e. the A and C phases), you should not have any severe voltage imbalance assuming the utility has sized their transformer correctly.

There are two separate Systems in the Main Electrical Room.

Single Phase 120/240 volts off one pole mount transformer source.

Three Phase 230 volts from a Bank of pole mounted transformers from another Pole.

We have had resistance from “BC Hydro” in Canada (not familiar to “SE” reference) to have more than one main shutoff to a Building for safety reasons, but for “complex” Facilities had been allowed to leave existing Single phase 120/240 volt supply for motors needing 240 volt and add three phase 120/208 volt or 347/600 volt as 277/480 volt is not available anymore. ( yes, that’s alot of variables and can be confusing)

 

[curt swartz]

There are two separate Systems in the Main Electrical Room.

Single Phase 120/240 volts off one pole mount transformer source.

Three Phase 230 volts from a Bank of pole mounted transformers from another Pole.

We have had resistance from “BC Hydro” in Canada (not familiar to “SE” reference) to have more than one main shutoff to a Building for safety reasons, but for “complex” Facilities had been allowed to leave existing Single phase 120/240 volt supply for motors needing 240 volt and add three phase 120/208 volt or 347/600 volt as 277/480 volt is not available anymore. ( yes, that’s alot of variables and can be confusing)

You keep saying 3 phase 230. Is it a 3-wire or 4-wire supply? If 4-wire how do you know if it Delta or Wye? Have you tested the voltages between all phases and all phased to ground?

BTW. You need to updated your profile to included your location and profession.

 

[jim dungar]

We have had resistance from “BC Hydro” in Canada

Is this installation occurring in Canada?

The SE abbreviation is commonly used for Service Entrance, meaning the utility.

If your 230V service is 3 transformers (closed delta) it would take an extremely large 1 phase loading to cause a voltage imbalance. If your 230V service is 2 transformers (open delta) the imbalance problem will depend on your which phases your loading is on. Is the utility aware you are adding load?

Please update your profile for Location and Occupation. A lot of user profile information did not transfer when this site was updated years ago.

 

[powerplay]

230 volts is not a standard supply voltage in the US. A typically Delta supply is 240 volt 4-W. Unless this is a heavy industrial building it unlikely you have a 3-wire un-grounded supply.

The voltage should not be fluctuating unless you are really overloading the transformers. Most 4-wire Delta systems are open Delta designed for most of the load on the single phase mid-point grounded winding with minimal 3 phase load. If the building has a large 3 phase load the supply will be a closed Delta.

230 volt is not a standard supply in Canada as well but seen, but in an old neighborhood encountered ungrounded 3 wire delta for machinery to work until fault repairs can be scheduled than blow fuses immediately.

In the building we are working in the Disconnect for the one ground floor suite is labelled only “230 volts” on the lamacoid and is a 400 amp fused switch.

Our available 4 wire systems are typically 120/208 volt, or 347/600 volt.

Corner grounded systems I believe needing to ground the “A” Phase in school, but don’t recall encountering it yet so assuming the “230 volts” is ungrounded Delta but will confirm when able to gain access from Tenant.

 

[powerplay]

Is this installation occurring in Canada?

The SE abbreviation is commonly used for Service Entrance, meaning the utility.

If your 230V service is 3 transformers (closed delta) it would take an extremely large 1 phase loading to cause a voltage imbalance. If your 230V service is 2 transformers (open delta) the imbalance problem will depend on your which phases your loading is on. Is the utility aware you are adding load?

Please update your profile for Location and Occupation. A lot of user profile information did not transfer when this site was updated years ago.

Yes, I am in Canada “eh” !

I have enjoyed the forums and hear we are striving towards “NEC”, so may be blind to some code references, but appreciate the theory and feedback !

I have only seen “clusters” of three transformers on poles whether three or four wire, or a single one for “SE”.

It is sounding like using ungrounded delta 230 volt Panel is not going to be an issue to use for a double pole breaker for 30 amp Expresso Machine.

Thanks, appreciate the feedback !

 

[ptonsparky]

Using equipment that is expected to have an equipment ground on a grounded system, with an ungrounded system is an issue. Here and I would guess on Canada.

 

[hillbilly1]

Hello All,

To provide power for a Three Phase DIshwasher and Three Phase Oven, we are planning to bring a combination Subpanel into the Suite with only 120/240 volts Single Phase.

Aside from checking for Ground Fault Detection Device and difficulty to balance the power of a single phase 240 volt 30 amp Expresso Machine, are there other concerns if ungrounded ? I will confirm details after arranging access for Monday.

Thank you for any insight !

It’s not like ground fault protection in a receptacle or switchgear. It is a ground detection if one phase goes to ground. It does not use CT’s.