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#184845 - 02/23/09 09:13 PM 208 volt contactor  
rcksmith127  Offline
Member
Joined: Apr 2005
Posts: 33
Danvers, Ma, USA
Need some help. Are there voltage ranges for a coil? I have a 3 phase 208 volt 3 hp motor with a NEMA Size 1 contactor with a 208 volt coil and a start/stop built in.
After the initial smoking of the coil, it had a 24volt coil instead of the 208 volt varity the box label stated. Lesson learned...
Anyway, I now have the correct coil but it won't pull in, it chatters. I read the voltage to actually be about 225 volts between phases which is not something I have come across much in this neighborhood.
Is there a "range" that the coil should work in? This started as a simple "favor" for a friend and it is turning into more of a time consuming problem.
Any input is appreciated.



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#184847 - 02/23/09 10:42 PM Re: 208 volt contactor [Re: rcksmith127]  
ghost307  Offline
Member
Joined: May 2005
Posts: 900
Chicago Illinois USA
Chattering is often the result of installing a DC coil on an AC control circuit.
When the drops to zero (before reversing polarity) the coil loses its field and the contactor starts to spring back open.


Ghost307

#184848 - 02/23/09 10:44 PM Re: 208 volt contactor [Re: rcksmith127]  
gfretwell  Offline


Member
Joined: Jul 2004
Posts: 9,069
Estero,Fl,usa
Is this the type with a pick and hold coil, selected by a side switch? You may be wired to the hold side.


Greg Fretwell

#184854 - 02/24/09 12:08 AM Re: 208 volt contactor [Re: rcksmith127]  
smokey  Offline
Member
Joined: Apr 2001
Posts: 41
cctxusa
i am experiencing the same problem with a set of contactors that control heating elements for a water heater.they keep chattering .even after replacement.i am now in the process of replacing them with a larger contactor 70a instead of 50a .i am thinking that the load is to much for the contactor.im not sure if this is helpful to you.im not sure if the higher voltage would effect the contacts inside the contactor.


#184857 - 02/24/09 01:01 AM Re: 208 volt contactor [Re: smokey]  
JBD  Offline
Member
Joined: Jul 2001
Posts: 599
WI, USA
Load does not affect the contactor sealing in.

The three most common reasons that contactors make noise are:
Low coil voltage. Most coils will pull in at 85% and drop out at 65%.
Jammed mechanism from dust or worn slides.
And probably the most common; rust, dirt, or scratches on the magnet poles faces which prevent them from mating correctly.


#184860 - 02/24/09 10:02 AM Re: 208 volt contactor [Re: JBD]  
SteveFehr  Offline
Member
Joined: Mar 2005
Posts: 1,205
Chesapeake, VA
It could simply be defective from the factory. We ran into a few defective chattering contactor solenoids last year in an application where problems like that are unheard of (high-end UPS systems).

It can be hard to tell the difference between a wrong part and a defective one, especially if you're pulling the replacements from the same defective batch.


#184877 - 02/24/09 08:33 PM Re: 208 volt contactor [Re: SteveFehr]  
JBD  Offline
Member
Joined: Jul 2001
Posts: 599
WI, USA
One more question.

You say it does not pull in, it just chatters.
Do you mean that it chatters while you hold the Start button in and then it drops out when you release the button?
Not holding in would be caused by a bad holding circuit contact or a wiring error.
Chattering, like rapid pickup then dropout, could be a wiring error where a contact from the starter is actually turning the circuit off instead of holding the circuit on.


#184880 - 02/24/09 10:24 PM Re: 208 volt contactor [Re: JBD]  
mb95307  Offline
New Member
Joined: May 2008
Posts: 4
Ceres, CA
Most contactors are equiped with a shaded pole. This shaded pole holds the contactor shut while the AC current crosses the zero point. If it is chattering, this is the first thing that I would look for...


#184881 - 02/24/09 10:26 PM Re: 208 volt contactor [Re: mb95307]  
gfretwell  Offline


Member
Joined: Jul 2004
Posts: 9,069
Estero,Fl,usa
got my attention...


Greg Fretwell

#184890 - 02/25/09 09:39 AM Re: 208 volt contactor [Re: mb95307]  
SteveFehr  Offline
Member
Joined: Mar 2005
Posts: 1,205
Chesapeake, VA
Originally Posted by mb95307
Most contactors are equiped with a shaded pole. This shaded pole holds the contactor shut while the AC current crosses the zero point. If it is chattering, this is the first thing that I would look for...
How does that work, are there two solenoids in the contactor, one with a straight winding and one with a shaded pole?


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