shortround

Having worked in electronics for over 40 years, I still have trouble with just plain electrical stuff. Guess my wires are too small and my voltages too low.
I'm dealing with three phase power.
Ain't got none.
I need to build a rotary converter. Simple enough HOWEVER, the typical three phase is Delta wired (three wire) and I need a Wye wired (four wire) output. From what I've seen, a lot maybe most, 3 phase Wye is 208 VAC. My motor(the load) is 220-250 VAC. Ought to be simple. Not to this guy.
If there are any certificated AND knowledgeable big wire folks out there, PM me with a phone number and I'll give you a call. I'm creating a bald spot scratching my head.

Shortroundfeelingdumb out

electrifried

I cannot think of any motor that would require 4 wire from a phase converter.

Seperate the controls.

Fronty Owner

Our contractor electrician is licensed in AR. He knows his stuff, but he is probably gonna want some compensation for the help.
that being said, we run all our three phase motors delta. the only time I have ever used a wye connection is to pull a 277 for lights.

shortround

The motor is dual voltage 230/460.
Rated at 3 hp, 230 V 60 Hz. Also rated at 208 vac at slightly higher current.
9 wires going into the motor.
Data plate on motor reads 3 hp P4 Type TC-FX
Hookup is (hopefully clear enough) ;
Line to 1 , 2 , 3
1 tied to 7
2 tied to 8
3 tied to 9
4, 5, 6 tied together

Starting to rain, got to cover up some stuff.
Back shortly.

Shortround out

Fronty Owner

terminals 10, 11, and 12 are tired together internally in the motor.
basically, voltage passes thru two coils for low voltage, four coils for high voltage.

carl48

just do not connect anything to the middle leg will pm you my #

Fronty Owner

I haven't seen any motors with the middle legs available..

electrifried

The 10:44 post is the usual way of wiring a dual volt motor.

Leads 1 2 3 go to the output of the phase conv (with the proper switching and overload protection)

AlpineRAM

Over here we have the middle leg on some of these motors available to measure imbalance and trip a motor protection switch of the older type- the newer protection switches do compare the phase current internally.
The other use would be if you used the motor as a generator.

HTH

AlpineRAM

Fronty Owner

yea, but europeans do weird things..
actually, the only real complaint I have is the OCD that is required in grounding. I mean come on, two pieces of stainless steel cable trays bolted together doesn't need a separate ground strap between the two.

carl48

if you look at the pix of the y where 10 11 and 12 come together is where you normally connect your neutral to. on motors it is not needed. on most loads it does not make any difference if the source or load is delta or y

DaveB.inVa

As others have said you don't need the fourth wire going to the center point of the wye.

If you're building the rotary phase converter just build it according to the instructions you have whether the idler motor is delta or wye wound. For your idler motor use at least 1.5X the size of the motor your going to power.

Also don't power any single phase loads from the manufactured phase, better yet, dedicate the circuit to your load. Any load past the idler motor should just be a 3 phase load. Get your lights and such from somewhere else. It would be alright to use the motor circuit for your controls, just don't use the manufactured phase.


AlpineRam/Fronty,

The center point of the wye is nearly always available here as well. What you are referring to is called differential protection. You can arrange it in quite a few different ways, from having a set of current transformers (CT's) on the incoming lines and on the center point of the wye or just running one CT per winding with the incoming line running in through the CT and then the center point cable running back out through the CT with the center point being made up external to the CT's.

Most newer electronic relays can compare the phase current internally, called residual differential protection. However this isn't preferred and is not as accurate as using a true differential CT set. Its sortof the cheap way out as you don't have to buy any additional materials, but the protection simply isn't as good.

Where I work, if we have differential protection on a motor it will be a true differential relay, we don't use residual for those reasons. An internal fault on a large motor can be very destructive and you want the differential to be as sensitive as possible without causing nuisance tripping. On large motors if you catch the internal fault before much happens it can often be repaired.

On smaller stuff its usually just easier to rewind it or junk it altogether.