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Old 02-04-2010, 11:22 AM   #1
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reversing contactors, dismantle and modify


times are tight, I need a pretty big three-pole contactor, so used is OK. my finished product doesn't have to pass code or ANY sort of elec'l inspection. I've noticed reversing contactors sometimes sell for less than 'normal' three pole contactors on ebay. I need to end up with something in the 'nema size 2' range. thinking maybe I can buy a reversing contactor, remove the 'additional crossbar' connectors, and end up with a normal (non-reversing) contactor plus some spare contacts...obviously, I'm not talking about the 'new-fangled' solid-state contactors here (nor do I want one)

so, that a doable do?

if cutting or grinding (of the phenolic contactor body, or of steel, or copper bars is involved, I can handle all that "no sweat"

please, no 'dire safety warnings' or 'OSHA threat' type replies. this is just a 'assuming the correct skillset, and the right tools, can it be done?' type question; not looking for 'binding legal opinions' or seeking safety advice

thanks, guys

shag
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Old 02-04-2010, 11:58 AM   #2
 
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Short answer: no, it shouldn't be done; yes, it can be done. Exactly how will depend on the manufacturer and model.

Easiest way would be to use the reversing contactor as is without any modifications. As you know, the electrical interlocks and mechanical linkage prevents both contactors from being energized at the same time. If you don't provide control power to the 2ND contactor it can't come on so you have no problem.

If you you do remove the linkage and decide to control the 2ND contactor separately, remember the incoming power to the second contactor has two of the phases swapped and the load side of the contactors share a common overload block.

None of the above addresses proper fusing and disconnecting means.
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Old 02-04-2010, 08:02 PM   #3
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Most reversing contactors are simply two normal contactors that have both mechanical and electrical interlocks so that only one can be on at at a time. They also share an overload relay.

The mounting base is where you might run into trouble. Certainly, the reverse contactor can be removed, but it leaves half of the base unused. I suppose this part could be cut off, but I've never done it.

The power connections to the reverse contactor is either a set of busses, or simply wire. Either one is easily removed.

The mechanical interlock is easy to remove as well.

The electrical interlocks are wired through auxiliary contacts, again, easy to remove.

The reversing contactor usually doesn't have electrical ratings stamped on it, but almost all parts are interchangeable between the two.

This should be fairly easy to do.

Rob
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Old 02-04-2010, 08:12 PM   #4
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what are you trying to hook up?ive probably got a used 3 phase contactor from a condensing unit you can have it will work for ya
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Old 02-05-2010, 10:19 AM   #5
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Quote:
Originally Posted by shag_carpet View Post
times are tight, I need a pretty big three-pole contactor, so used is OK. my finished product doesn't have to pass code or ANY sort of elec'l inspection. I've noticed reversing contactors sometimes sell for less than 'normal' three pole contactors on ebay. I need to end up with something in the 'nema size 2' range. thinking maybe I can buy a reversing contactor, remove the 'additional crossbar' connectors, and end up with a normal (non-reversing) contactor plus some spare contacts...obviously, I'm not talking about the 'new-fangled' solid-state contactors here (nor do I want one)

so, that a doable do?

Yes, Its very doable and easy. Disassemble the reversing contactors and use all the parts as you like.

if cutting or grinding (of the phenolic contactor body, or of steel, or copper bars is involved, I can handle all that "no sweat"

Never alter the contactor. If you cannot use it as it is, do not use it at all.

please, no 'dire safety warnings' or 'OSHA threat' type replies. this is just a 'assuming the correct skillset, and the right tools, can it be done?' type question; not looking for 'binding legal opinions' or seeking safety advice

thanks, guys

shag
This is performed all the time in a pinch for control electricians. Usually temporarily until the correct parts can be obtained. But taking a reversing contactor set and separating them is no issue.

A good example: You need a reversing contactor set but only have single contactors. Two single contactors can be wired to work like a reversing contactor without the mechanical interlock.

How much do you plan to spend on a NEMA 2 starter? You can buy a new one for very cheap if you stay away from Square D and Allen Bradley. Look at "Benshaw and Weg" for low cost, high quality.
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Old 02-05-2010, 10:33 AM   #6
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Quote:
Originally Posted by Pro_DYIer View Post
Easiest way would be to use the reversing contactor as is without any modifications...
right, but space limitations being what they are, I'd prefer to fit the thing into a 'smaller rather than larger' enclosure...


Quote:
Originally Posted by Pro_DYIer View Post
None of the above addresses proper fusing and disconnecting means.
right, understood, thanks, pro

Quote:
Originally Posted by micromind View Post
not all quoted back, but rob's tremendously helpful reply was here
...
This should be fairly easy to do.

Rob
so *thanks* rob

Quote:
Originally Posted by plummen View Post
what are you trying to hook up?
well, I guess it's safe to divulge: I'm in the mid-stages of gathering parts to build a "ten hp idler motor" rotary converter. I'm wanting to make a "one button, self-starting" type. these are the component parts I've gathered so far. I have a "pretty good" idea of what parts I still lack, but "still a little imprecise" on the spec's, of some parts, eg: the contactor. I think it really 'ought to be' a motor starter, NEMA size 2. by the way, the 3 timers (pictured on site above) arrived and I tested them - they turned out to be a 'total bust', none of 'em work (they're non-functional for various reasons; I might post details and images of them and the 'whys' they're no good later). so that means I'm "back to" considering (needing to aquire) a potential relay, steveco 90-66 or equiv (that or another mini-timer) to 'fire off' the start caps, which, is 'probably not all that great' an idea)


Quote:
Originally Posted by plummen View Post
probably got a used 3 phase contactor from a condensing unit you can have it will work for ya
I *sure* appreciate that offer. not that beggars can be choosers, but how big is it? know what nema size it is? coil voltage? got an aux contact hangin' on it? (old, dusty, and pitted contacts "no big problem" )

tried to send you a PM, through the forum, but it appears 'that's an undoable do'. I'll contact you through your site's form-mail. or you can contact me direct e-mail through any 'page bottom center' link on my 'rotary converter parts' site above, or, here's where I'm at


*thank*you* very much, plummen
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Old 02-05-2010, 10:54 AM   #7
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Quote:
Originally Posted by J. V. View Post
This is performed all the time in a pinch for control electricians. Usually temporarily until the correct parts can be obtained.
right, understood, *thanks* JV

...

Quote:
Originally Posted by J. V. View Post
How much do you plan to spend on a NEMA 2 starter?
as little as possible. I'm like a SUPER-cheapskate . however (like with my recent speculative "3 timers" buy) sometimes I DO actually have to spend money (which makes me cry

Quote:
Originally Posted by J. V. View Post
You can buy a new one for very cheap if you stay away from Square D and Allen Bradley. Look at "Benshaw and Weg" for low cost, high quality.
have my eye on (a few more speculative, used/cheap) items on that bay site we all 'love to hate'....sort of a 'huge diceroll' what type of quality I'll get when I spend the types of money I'm lookin' to spend...I'd actually prefer to SWAP stuff (rather than spend money), seeing as I have a 1500 sq foot warehouse full of tools, hardware, and machines/machinery components...but that's not always practical (somewhat like myself

thanks again JV
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Old 02-05-2010, 10:58 AM   #8
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the one i have is a GE #CR353AB3BHOAB heres the specs off the side of it
:240v LRA 150
:480v LRA 125
:600v LRA 100

FLA 25

resistive amps per pole 35

let me know if it will workfor ya and illstick it in a box for ya,you just pay the shipping
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Old 02-05-2010, 11:38 AM   #9
 
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You may want to consider a combination starter which would include the disconnect, fuses contactor, overloads and room for your start stop buttons on the cover. There may be room for some additional components within the enclosure.
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Old 02-05-2010, 02:29 PM   #10
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Quote:
Originally Posted by plummen View Post
the one i have is a GE #CR353AB3BHOAB heres the specs off the side of it...illstick it in a box for ya,you just pay the shipping
thanks again *much* plummen. spec's (that i can comprehend) for contactors are harder to find than hens teeth - sorry to say this, but I'm more of a "how many poles does it have, what NEMA size is it, and what size hp motor is it rated for at 230 volts" type'a guy.

plummen, thanks again for your kind offer

Quote:
Originally Posted by Pro_DYIer View Post
You may want to consider a combination starter which would include the disconnect, fuses contactor, overloads and room for your start stop buttons on the cover. There may be room for some additional components within the enclosure.
I believe you're right about that, so I updated my wants list accordingly, about an hour ago. the 'learning curve' involved with these things is fairly steep...for ol' bubba here.

thanks pro

Last edited by shag_carpet; 02-06-2010 at 08:05 AM.
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