480 Volt Single Phase

[Electric-Light]

480/830v 3ph yielding 480 L-N is used in mining and petroleum fields.

Could it be used for street lights to where each pole would get 480v L-N, but the ground feeder carries 480/830 wye?

 

[iwire]

480/830v 3ph yielding 480 L-N is used in mining and petroleum fields.

In the US?

It just seems odd. That voltage puts you above 600 volts so now you need different equipment, conductors and installation methods but does not provide significantly more capacity than 600Y/347.

 

[Electric-Light]

In the US?

It just seems odd. That voltage puts you above 600 volts so now you need different equipment, conductors and installation methods but does not provide significantly more capacity than 600Y/347.

Yes. 600Y/347 is fairly common in some parts of Canada.

830Y/480 is used to reduce I^2R loss in long runs encountered in oil fields while allowing many 480v motors to be used by rewiring into wye configuration

 

[kwired]

Yes. 600Y/347 is fairly common in some parts of Canada.

830Y/480 is used to reduce I^2R loss in long runs encountered in oil fields while allowing many 480v motors to be used by rewiring into wye configuration

Can you explain what you mean by this. An individual three phase motor would have to be designed for 830 volts. You could connect 480 volt single phase motors from line to neutral and balance them across phases, you would still need over 600 volt wiring methods with either installation.

 

[iwire]

830Y/480 is used to reduce I^2R loss in long runs encountered in oil fields while allowing many 480v motors to be used by rewiring into wye configuration

I sure wish I understood what you mean.

Are you talking about running 480 volt single phase motors L to N from a 830Y/480 supply?

 

[LarryFine]

I would rather see 240 volts to ground instead of 480, just for a little more safety should someone be exposed to live conductors.

As well as less insulation stress.

 

[broadgage]

I sure wish I understood what you mean.

Are you talking about running 480 volt single phase motors L to N from a 830Y/480 supply?

A 480 volt 3 phase motor would normally have 3 windings each designed for 480 volts, such a motor would most commonly be utilised on a 277/480 volt system with the windings connected in delta such that each receives the 480 volts intended.
The same motor could be connected in Y to a 480/830 volt system, each winding would again receive the intended 480 volts and the the motor would work just as well.

A similar situation exists in the UK with most motors being 415 volt 3 phase and connected in delta to a 240/415 system.
In oil refineries and other extensive premises, the exact same motor is connected in Y or star as we call it here, to a 415/720 volt system.

In both cases the higher voltage allows the use of standard motors whilst saving on cable costs and losses.

 

[iwire]

A 480 volt 3 phase motor would normally have 3 windings each designed for 480 volts, such a motor would most commonly be utilised on a 277/480 volt system with the windings connected in delta such that each receives the 480 volts intended.
The same motor could be connected in Y to a 480/830 volt system, each winding would again receive the intended 480 volts and the the motor would work just as well.

A similar situation exists in the UK with most motors being 415 volt 3 phase and connected in delta to a 240/415 system.
In oil refineries and other extensive premises, the exact same motor is connected in Y or star as we call it here, to a 415/720 volt system.

In both cases the higher voltage allows the use of standard motors whilst saving on cable costs and losses.

The problem is that once we go over 600 volts we have to jump into the next level of equipment ($$$$) and if the motor is only labeled 480 I cannot supply it 830 no matter how I make the connections and not have a code issue.

So I think I am still missing something.

 

[kwired]

A 480 volt 3 phase motor would normally have 3 windings each designed for 480 volts, such a motor would most commonly be utilised on a 277/480 volt system with the windings connected in delta such that each receives the 480 volts intended.
The same motor could be connected in Y to a 480/830 volt system, each winding would again receive the intended 480 volts and the the motor would work just as well.

The motor would have to have 12 leads to be able to do that (on motors that are 230/460 rated) or 6 leads if 460 volt motors.

A (common in the US) 230/460 Y connected motor with only 9 leads would not work at all. If it had 12 leads it would, but I've never seen a wye motor with 12 leads, there is no need for leads 10,11,12 to be brought to the terminal box as they are tied together for either voltage configuration.

Many delta connected motors do not have 12 leads either because for 230/460 leads 10,11,12 connect to the same place for either voltage so they don't bother bringing this connection to the terminal box, but those leads would need to be reconfigured for the 830 application.

It also would not be allowed by NEC to use the usual 600 volt switchgear, controller, or conductors for the 830 application.

 

[Electric-Light]

There are several articles in IEEE on this.

I'm not sure if refineries, mines and oilfields fall under the jurisdiction of NEC. They maybe under NESC.

 

[dbuckley]

Nope, 1 hot, 1 neutral, 1 ground. Blk, Wht, Grn. It's run in pvc or hdpt conduit.

Thats a little odd; thats the NEC compliant way of doing it, and the way that private streetlighting is done, but normally public street lighting isn't done in compliance with the NEC, its just two conductors.

 

[broadgage]

The motor would have to have 12 leads to be able to do that (on motors that are 230/460 rated) or 6 leads if 460 volt motors.

A (common in the US) 230/460 Y connected motor with only 9 leads would not work at all. If it had 12 leads it would, but I've never seen a wye motor with 12 leads, there is no need for leads 10,11,12 to be brought to the terminal box as they are tied together for either voltage configuration.

Many delta connected motors do not have 12 leads either because for 230/460 leads 10,11,12 connect to the same place for either voltage so they don't bother bringing this connection to the terminal box, but those leads would need to be reconfigured for the 830 application.

It also would not be allowed by NEC to use the usual 600 volt switchgear, controller, or conductors for the 830 application.

I agree that it would not work with a standard USA spec motor.
UK ones normally have 6 connections only, one to each end of each winding.
Each winding is designed for only a single voltage, often 415 volts.
These windings may be connected in delta to a 240/415 volt system, or in Y to a 415/720 volt system.
Here in the UK up to 1,000 volts may be used on standard cable which is typicly rated at 600/1000 volts, meaning up to 600 volts between any wire and earth, and up to 1,000 volts between wires.
AS you point out, the limit is 600 volts in the USA which would appear to rule out a 830 volt system unless special and costly equipment was used.
(UNLESS IN SPECIAL APPLICATIONS NOT CONTROLLED BY THE NEC)

 

[kwired]

The motor would have to have 12 leads to be able to do that (on motors that are 230/460 rated) or 6 leads if 460 volt motors.

A (common in the US) 230/460 Y connected motor with only 9 leads would not work at all. If it had 12 leads it would, but I've never seen a wye motor with 12 leads, there is no need for leads 10,11,12 to be brought to the terminal box as they are tied together for either voltage configuration.

Many delta connected motors do not have 12 leads either because for 230/460 leads 10,11,12 connect to the same place for either voltage so they don't bother bringing this connection to the terminal box, but those leads would need to be reconfigured for the 830 application.

It also would not be allowed by NEC to use the usual 600 volt switchgear, controller, or conductors for the 830 application.

After thinking about this more I don't see that the typical 230/460 Y motor would work at all, even if you had access to leads 10,11,12. By reconnecting in a delta connection and applying 830 (which I had in my mind initially) you would place 830 volts across windings that are designed to have 277 applied across them.

It would work with a 230/460 delta motor (if access to all 12 leads) to connect them in a wye configuration and apply 830 volts.

 

[Electric-Light]

The big machines are refineries are probably 480v only rather than dual voltage.

There is a standard on the usage of 830v system in IEEE 464-1981: IEEE Recommended Practice for Grounded 830 V Three-
Phase Electrical System for Oil Field Service

but I don't have access to the standard.

When starting current must be controlled wye start/delta run is one of the methods.

http://www.usmotors.com/Service/Bulletins/Issue7-May03.pdf

A 480v hooked up in wye esssentially acts as if it's hooked up to 277v and once its up to pre-determined conditions, its wired back to delta for full voltage. The motor must have leads to access both ends of winding for wye hookup, but they should be provided for delta-wye starting system.

If it's connected to 830v in wye hookup, it'll be just like connected to 480v source in delta hookup, except that insulation needs to be able to withstand the added stress, just like VFD use.

 

[markschmitter]

480VAC 3 Phase

480VAC 3 Phase

I have been under the impression that 480 is only three phase. I have a Parking Lot light with 480 volts........only two phase wires and one ground. Is this right or should I have 3 phase wires and a ground........no neutrals are run to the pole. The breaker feeding these lights are 2 pole 20 amp.

Yes, you are still using 480 volt 3 phase. To make up 480 VAC you have any 2 of the 3 legs of 277Volt. A typical 480 Volt 3 phase system is 3 legs of 277 volt at the 3 phase cycle seperation. So much light that is 480 volt requires 2 legs of 277 volt and the ground.

 

[jmellc]

480 volt street lighting. One phase wire, 1 neutral, 1 ground.

That would be 277, not 480.

 

[iwire]

That would be 277, not 480.

Not in this case.

In this case hot to grounded is 480.

 

[Cavie]

That would be 277, not 480.

Sorry Mel. It took me a few days to get my head around it also. 40 years experiance in the electricticial trade. EC and Fl State inspector and I find somthing new every day. 480 volt street lighting can and is 1 hot ,1 neutral, 1 ground. At least with Florida Power and Light.

 

[Electric-Light]

Sorry Mel. It took me a few days to get my head around it also. 40 years experiance in the electricticial trade. EC and Fl State inspector and I find somthing new every day. 480 volt street lighting can and is 1 hot ,1 neutral, 1 ground. At least with Florida Power and Light.

So what's the derivation? Delta or 830Y/480?

 

[kwired]

So what's the derivation? Delta or 830Y/480?

Could easily be 480 volt single phase source also.