480 v 3 phase 20 hp well pump

[ronnator]

I have a customer that is having a 480 v 3 phase well pump installed. The customer is paying the power company to install transformers at the pole. should this be set up as a delta or wye? I havent seen the pump or controll unit.

 

[Cow]

I like wye.

 

[hurk27]

If 277 is not needed, I like delta, you don't single phase the pump if the utility looses a phase into the transformers.

 

[kwired]

Is the POCO giving you a choice? Sometimes you get what they will give you. Most of the time they will likely give you Wye but if in a remote area they may opt to only run two primary phases and neutral then you are stuck with open delta.

 

[Jraef]

Yeah, usually they don't give you a choice because it has more to do with what they will support as standard equipment and spares etc.

But the motor won't need 4 wires, so if they give you a Wye service, you just dutifully terminate the Neutral on the landing lug on whatever is your SUSE disconnect and that's where it stays. Not your problem really.

 

[ptonsparky]

If at all possible the POCOs here are going with Wye, but again you don't get the choice. One customer at the end of everything has a 480v open delta grounded phase secondary , with only two primary phase conductors coming in. Thought I had it figured out once, but it's gone again.

 

[hurk27]

Well guess we are lucky, we can get both 240 volt or 480 volt 3-wire deltas, here is our utility standard:

http://www.nipsco.com/Libraries/Builders_Developers/Electric_Standard_22500.sflb.ashx

 

[Ragin Cajun]

Stay away from 480V delta!

RC

 

[kwired]

Stay away from 480V delta!

RC

Why? Its the idiots that don't understand what they are working with that get into trouble with it. A motor could care less what the source is as long as the voltage is within motor specs and phase angles are correct. It won't care if one of the phases happens to be grounded or if there is no ground at all either.

 

[Ragin Cajun]

I assume you are referring to a true 480V delta, not just a 480V wye where you bring the neutral to the main disconnect only. Just be sure you carry a good EGC throughout to serve as a ground fault return path.

I will have to dig up some olde references I have for details.

But, unless you have a good ground detector system and maintain the system by clearing the first ground, the second will cause voltage spikes through the system and wrecking havoc.

RC

 

[kwired]

I assume you are referring to a true 480V delta, not just a 480V wye where you bring the neutral to the main disconnect only. Just be sure you carry a good EGC throughout to serve as a ground fault return path.

I will have to dig up some olde references I have for details.

But, unless you have a good ground detector system and maintain the system by clearing the first ground, the second will cause voltage spikes through the system and wrecking havoc.

RC

Not all 480 volt delta systems are ungrounded systems. They can be grounded phase or mid point of one phase is grounded systems.