Please please help with a switch issue hooking up my 3 phase

cincinnati JA

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Ok I have the 5hp rotary phase converter which is a 3 phase motor which is run of 2 legs single phase and the third leg is generated by the motor . Now the issue is I have a master electrician friend who bought me a fusible disconnect that is called a pull type . It is a good enclosure but I cannot use it as an on off switch or let's say I don't feel comfortable using it as a on off switch. So I went to a huge electrical supply store and talked with a card carrying electrician about a on off switch or start stop switch and I wanted it inline with the power going to the phase converter but he kept telling me that it wouldn't work that way. And blah blah he brought out this switch which looked exactly like what I wanted and I bought it and was happy but I pulled it apart and it is a momentary switch which I am assuming I must use a relay with . Which is fine but I have no idea how a momentary switch works with AC power .

I think I understand that the momentary switch energizes the relay and starts the machine , maybe? But I'm still confused . Here are photos can someone please explain this to me . What I want, whether is be a momentary button or breaks type start stop, I want to be able to push start and stop to turn the machine on or off.

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This is the inside of the phase converter I have close ups if anyone needs them .

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These are the two switches the one on the left is a breaker type start and stop and the one on the right a momentary push to start .

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This is the inside of the breaker type switch this is for a three phase but can be used as a single phase as well. But I want to keep it on the shaper head with my Cincinnati mill. Obviously this type switch works with the power online to the motor... I don't know why that electrician was telling me switches can work this way.

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This is the inside of the momentary which I'm not exactly sure how this works so if someone could explain that would be awesome! But again I think I need a relay with this one .

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This is the inside cover I've the disconnect


Basically I have a fusible disconnect and I want a start stop switch in between that and the phase converter . Or should I just take out this disconnect and put a knife type disconnect and just use that as my on off to the converter ? No the converter did not come with its own on odd switch. When you apply power to it . It comes on .

Please please help!
 
Please review the options in this document. There are example schematics in it that should help.

http://www.eriebearings.com/motor-control/files/eaton-motor-control-basic-wiring.pdf

Tony , first off thank you very much for that. I don't know much about electronics so even that article confuses me . I mean I can basically understand it but all of the schematics are for 3 phase momentary buttons . I need single phase 240v hook up going into a phase converter that generates a third leg "T3" I just read a thread on here and I am guessing I need a starter or a relay of some sort ? Maybe I should just get the knife type disconnect and move on!
 
Are you wanting control of the generated 3 phase with the start/stop station, or control of the phase converter?
 
if you were so inclined you could use the start/stop to operate a contactor or motor starter.
that would effectively disconnect the main power when open.
your on/off switch doesn't appear to have the capacity to switch large inrushes of current or voltage.
the contactor or motor starter does have the capacity for large voltage/amperage inrush if sufficiently rated, to switch all power legs simultaneously.
the on off switches would only switch control current to energize the contactor coil.
 
Are you wanting control of the generated 3 phase with the start/stop station, or control of the phase converter?

I want to control the phase converter motor itself on or off. It will be a switch between the disconnect and the phase converter . After the converter it goes to a 3 phase panel and then from there my mill and my grinder will be hooked up and they have their own switches. In your opinion is a knife type disconnect ok to use as a on off switch on a regular basis or is it not ideal? I think I need to sit down and read the link you have me again and do some more educating of myself . It's a lot to take in . I wonder how much it would cost to buy a starter and a relay or if I can get away with just a relay ... Or from the photo of the converter can you see where a starter or relay would be to start the motor? Or 3rd option , just by a non fused knife switch to cut it on and tie it into the fused disconnect .

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if you were so inclined you could use the start/stop to operate a contactor or motor starter.
that would effectively disconnect the main power when open.
your on/off switch doesn't appear to have the capacity to switch large inrushes of current or voltage.
the contactor or motor starter does have the capacity for large voltage/amperage inrush if sufficiently rated, to switch all power legs simultaneously.
the on off switches would only switch control current to energize the contactor coil.

So I understand the breaker type switch not being able to carry the load but why? Because it cant withstand the consistant load And does the momentary allow it to carry the load because it is momentary ? So all I need is a motor contractor or starter in between the the switch and the wires to the lugs on the converter ? How would I choose what contractor or starter?
Also the breaker type was hooked up to the 3 phase shaper motor which was hooked up after the starter so is that why that switch can work as a on off on the motor?
 
Since your phase converter is powered by single phase, you only need a 2 pole switch, or contactor.....whichever you choose. It is not necessary to have a contactor if you have a heavy enough switch, BUT, it would be more convenient to use one. In that case, you would set up your push button station to energize the coil on the 2 pole contactor (relay with heater). You will need to either use a contactor with an adjustable heater, or a properly sized fixed heater.

Can you give us the make and model of the phase converter? I'd like to see the schematic for it before I give further advice.
 
So I understand the breaker type switch not being able to carry the load but why? Because it cant withstand the consistant load And does the momentary allow it to carry the load because it is momentary ? So all I need is a motor contractor or starter in between the the switch and the wires to the lugs on the converter ? How would I choose what contractor or starter?
Also the breaker type was hooked up to the 3 phase shaper motor which was hooked up after the starter so is that why that switch can work as a on off on the motor?[/QUOTE]

the breaker switch may not have sufficient capacity to carry the full motor load, you can still gain it's use you would just have to design the circuit differently than the momentary. just remember switching control circuits can be done with light duty switches, there is usually less than a couple amps involved.
when switching motor loads there is potential to switch larger amounts of current, therefore the need for more robust parts.

yes, a contactor or motor starter of your choice can be installed to provide electrical control.

Starters can be rated in Horsepower or Amps drawn. i would suggest for economy to use definite purpose contactors whenever possible. they are widely used in the Air Conditioning,Refrigeration,and industrial applications way to numerous to list.
they are sturdy, cheap and available easily.
i always over rate my contactors, if the circuit calls for a 15 amp, i install a 20 or 25 amp and they last for a long service life.
EBAY is packed with them.

that's correct, the breaker shut off all three phases at the same time. but there is no rule stating that you must use all three lugs at the same time. a single phase motor will pull a lot of current to start, even more current will be drawn by a 3 phase motor trying to start on single phase. once the pony motor is running current levels are dramatically reduced.
start up is the hardest part, once the pony is running the single phase we introduced to the motor is auto generating the third leg through induction, giving the 3rd phase
 
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