Contactor controlling fans

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Liteitup

Member
I want to set up a contactor controlling 5 circuits on a timer. Any suggestions? Do I use an electrically held contactor (N.O.)? Mechanically held? Fans will run for about 18 hrs a day. Fans are 1/4 HP, 115vac.
 
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dicklaxt

Senior Member
I see no reason to use anything other than an off the shelf N.O. timer controlling the contactor which in turn would control the 5 motors,,,,,,,,,there is of course several ways to configure the system schematic but would need to know more info.

dick
 
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Liteitup

Member
Ok I used: 2 pole and 3 pole NO contactors. Timer pulls contactors in from 6am to 12 midnight. I mounted the contactors inside a pullbox. Everything was working fine. Now I get a call from client says there is a loud buzzing coming from pullbox so he turned off timer. What is going on? Going to check it out tomorrow morning. Could it be heat inside the pullbox?
 
T

teco

Senior Member
Location
Mass north shore
Did you use all new controls? If they are used, the contacts on one of them could be pitted and are not seating together correctly. Remove them and check um out. If new maybe your mounting screws are not tight. One of the coils not seated right. Are they din rail mounted? Sometimes din rail vibrates a lot if they are din mounted. As already said there is always some sound and vibration but it shouldn't be so loud that someone has to shut it off. Disconnect one coil and see if its just one unit making the noise. Check all connections. If nothing works try rubber washers or return it.
 
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LarryFine

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
When the pole pieces don't meet squarely and fully, the contactor hums, often loudly. The moving pole piece usually pivots on the armature.

I have quieted old contactors by lubricating the pivot with WD-40 and working the pivot loose. You may have to disassemble the contactor a bit.
 
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hillbilly1

Senior Member
Location
North Georgia mountains
Occupation
Owner/electrical contractor
Many times it's debris from metal shavings, concrete dust or other contanimants getting between the pole pieces. Sometimes squirting it with WD 40 or compressed air will clear it.
 
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Liteitup

Member
They are both new contactors. They are attached directly to the pull box with 8/32's. I will see about it tomorrow. Also were not noisy besides a little hum upon installation.
 
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Liteitup

Member
Ok, checked the contactors. What a loud buzz it was making! What was it? Well it seemed to be that they were kind of sticking or not seating properly. I turned off the fan circuits. Of course I checked all my voltages and that looked fine. I then opened and closed the contactors first with the time clock and then manually. 4 or 5 times. The buzzing went away. Could not get the buzzing to come back. This is good but will it come back again? I really hope not. Client is happy for now but if it happens again...
 
LarryFine

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
Liteitup said:
I then opened and closed the contactors first with the time clock and then manually. 4 or 5 times. The buzzing went away.
Click to expand...
It sounds like you worked the contactors until the pole pieces moved a bit and mated closely. It should stay quiet.
 
C

Cow

Senior Member
Location
Eastern Oregon
Occupation
Electrician
I'd bring another new contactor or two out with you next time. Just change it, callbacks are expensive.

I usually rap on the side of the contactor with my screwdriver handle when they hum to loud. Most of my installations are ag or industrial, so the customers wouldn't even notice the hum. It just bugs me...
 
G

gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
101018-1735 EDT

Change to latching contactors. You do not need an energized coil all day long. Or change to DC excitation if these contactors will work well on DC. It would be a substantially lower voltage for the same coils. Or change coils to ones for 120 VDC.

AC relays, contactors, and solenoids are always a possible source of noise for the reason Larry mention above.

Do you have one or many contactors?

Also your mounting method created a nice sounding board.

.
 
Jraef

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
Cheap contactors are cheap for a reason. I'd be willing to bet you used Definite Purpose contactors, the cheapest of the cheap.

"Lighting contactors" are more expensive because... they don't buzz!

There are also some very nice IEC contactors out there that do not buzz. Siemens, LG, Telemecanique, Allen Bradley etc. are all good in my experience. ABB, not so good as far as buzzing goes. GE is the worst, but at least a little bit better than DP... Nothing is worse than DP contactors.
 
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Liteitup

Member
It is both of them. Although not sure at the same time. When I was there last I got them to buzz one at a time. When they are pulled in and you jiggle the solenoid the buzzing would go away. They are mounted side by side inside of a pull box and the pull box is mounted on the wall above the time clock. I admit they were probably the cheapest ones at the supply house. In the $20-$30 range if I remember right. My supplier says he has sold "thousands" of them without a complaint. I forget the brand. I was originally thinking of a mechanically locked contactor but thought it might be too pricey. I am leaning towards the cheapness factor here. The wiring is correct, voltages correct, current was normal. I'm baffled. Maybe I should have spent the extra money. Now two callbacks later...
 
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