3 phase question have 208 v, need 460v

[Stevenfyeager]

This is a stupid question, as an electrician who does almost all residential work and hardly any commercial work. My customer wants to install a tilting machine and it’s specs on line say 3 ph 460v. The building has 3 ph 120/208 v. Is there a converter for this ? Or should I call the mnfr to ask if it’s adaptable? Thank you.

 

[texie]

Just use a 208 delta to 480Y step up transformer. Be mindful of all grounding, bonding, OCPD rules for an SDS.
I'm sure your supplier will temp you with a 480 delta X 208Y that they have in stock and tell you to reverse feed it. Bad idea on a number of levels.

 

[don_resqcapt19]

You need a step up transformer, 208 to 480 volt with a delta primary and a wye secondary if the machine is not dual voltage.

You can get away with reverse feeding a 480 to 208 transformer, but the 480 volt side is typically a delta winding and you would need to either make it a corner grounded system or provide ground detectors to indicate a ground fault on an ungrounded 480 volt system.

 

[kwired]

This is a stupid question, as an electrician who does almost all residential work and hardly any commercial work. My customer wants to install a tilting machine and it’s specs on line say 3 ph 460v. The building has 3 ph 120/208 v. Is there a converter for this ? Or should I call the mnfr to ask if it’s adaptable? Thank you.

You need a three phase transformer with 208 primary and 480 delta or 277/480Y secondary

Or if machine is reconfigurable for more than one voltage you possibly can connect it to 208.

 

[Strathead]

You need a step up transformer, 208 to 480 volt with a delta primary and a wye secondary if the machine is not dual voltage.

You can get away with reverse feeding a 480 to 208 transformer, but the 480 volt side is typically a delta winding and you would need to either make it a corner grounded system or provide ground detectors to indicate a ground fault on an ungrounded 480 volt system.

This my be my stupid question, he said the machine is 460 s why does he need a 480/277 Wye secondary? He doesn't indicate needing a neutral, but if he creates it he has to run it. Doesn't make sense to me.

 

[texie]

This my be my stupid question, he said the machine is 460 s why does he need a 480/277 Wye secondary? He doesn't indicate needing a neutral, but if he creates it he has to run it. Doesn't make sense to me.

Because if you have a delta secondary it will have to be ungrounded or corner grounded. Both present a lot of issues to deal with.

 

[jim dungar]

This my be my stupid question, he said the machine is 460 s why does he need a 480/277 Wye secondary? He doesn't indicate needing a neutral, but if he creates it he has to run it. Doesn't make sense to me.

It is easier to ground the wye secondary of t h an if it was a delta.

 

[kwired]

Because if you have a delta secondary it will have to be ungrounded or corner grounded. Both present a lot of issues to deal with.

Or there is center of one phase grounded (high leg delta)

It is easier to ground the wye secondary of t h an if it was a delta.

Is easy to ground any of them systems and takes similar effort to do so on all of them. Many wrongly think that grounding something other than a neutral is somehow going to blow up in your face. Wye system simply gives you equal voltage to ground from the three ungrounded conductors.

 

[GeorgeB]

My customer wants to install a tilting machine and it’s specs on line say 3 ph 460v. The building has 3 ph 120/208 v. Or should I call the mnfr to ask if it’s adaptable?

You've several electrician replies, mostly, IMO, good ones. Let an engineer step in here.

I'd say that probably 90% of smaller, say 50 HP and under, 460-3-60 motors are dual voltage motors, and thus 100% suitable for 230-3-60. Many, but not all, are suitable for 208-3-60.

Way over half of the machines will have a control transformer that will accept 230V.

If I were asked to specify equipment for this, the FIRST THING I would request is the machine tag info. After that, the recommendations here can be analyzed.

One issue if is is adaptable is that the starter/drive will likely need to be changed. The step up (208:480) transformer gets you around that issue and the potential 208 suitability of the motor.

 

[don_resqcapt19]

This my be my stupid question, he said the machine is 460 s why does he need a 480/277 Wye secondary? He doesn't indicate needing a neutral, but if he creates it he has to run it. Doesn't make sense to me.

There is no requirement to run the neutral, from the wye system, but it is typically easier and cheaper to install the grounded system than it is to provide the ground detection required by 250.21(B). The conductors from the transformer to the first disconnect would be the three phase conductors and a supply side bonding jumper. The exact same conductors that are required for an ungrounded system.

The other option would be to use a corner grounded system.

 

[oldsparky52]

How big of a load are we talking about?

 

[Stevenfyeager]

I just got more info from the customer : 208-230/460 VAC 2 hp 7.8-8.2/3.1 FLA 1725 rpm or 208-230/460 VAC , 2 hp 5.6/2.8 3450 rpm
Thank you for your help.

 

[Stevenfyeager]

So my existing 208 is good, correct ?

 

[jim dungar]

Or there is center of one phase grounded (high leg delta)
Is easy to ground any of them systems and takes similar effort....

Don't be argumentative.
Corner grounded systems require non-typical equipment and can be confusing to many electrons. 480Y/277V neutral grounded systems are much more common and likely understandable by the OP.

 

[kwired]

So my existing 208 is good, correct ?

Most likely. Does it come with controls or do you need to supply motor controller? You possibly need to select proper size and overload protection if it doesn't come with controls or still possibly change out overload or elements even if it does.

 

[jim dungar]

So my existing 208 is good, correct ?

You may need to change some wiring, but yes your 208V is okay.

 

[kwired]

Don't be argumentative.
Corner grounded systems require non-typical equipment and can be confusing to many electrons. 480Y/277V neutral grounded systems are much more common and likely understandable by the OP.

I suppose some places it is pretty uncommon to see delta systems period, at least at under 600 volts.

Similar fundamentals still come into play with a simple two wire secondary.

 

[Stevenfyeager]

Thanks. For the amps, wire size, just #12 Cu ? And only a ground, no neutral ?

 

[ActionDave]

Thanks. For the amps, wire size, just #12 Cu ? And only a ground, no neutral ?

What does the nameplate on the machine say about the amp rating?

 

[hillbilly1]

You will need to find out if it has a starter that uses line voltage for control, or a small step down transformer with adjustable input taps
( most likely) . If it is line voltage, you will need to change the starter coil, and don’t forget to change the overload heaters or dial adjustment if so equipped to match the load amps at the new voltage.