DP contactor coil.

Status
Not open for further replies.

Besoeker

Senior Member
Location
UK
Hooking equipment up to temp power source we find a 10 hp compressor that has run for years @ 480v. Coil on contactor is 240v. Is there enough impedance on this type of coil that it doesn't matter? SQ D.

If you're asking if a 240V coil work on 480V then the answer is don't even think about trying it.
 

topgone

Senior Member
Hooking equipment up to temp power source we find a 10 hp compressor that has run for years @ 480v. Coil on contactor is 240v. Is there enough impedance on this type of coil that it doesn't matter? SQ D.

If there is no transformer, did you see a neutral conductor involved in the control wiring? 480/sqrt(3) = 277 volts just about 15% over the coil rating. If the location is very far from the DP, actual local voltage could be lower than the 480 volts at the source giving the coil a lease in life. A control wiring diagram can be helpful here.
 

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
Got a model number and mfr of that DP contactor? Furnas, who was very big in DP contactors, had a dual voltage coil option, 240 or 480 sepending on how you connected it.
 

Besoeker

Senior Member
Location
UK
Why, how did it work for so long? Any thing I miswired takes only seconds for the smoke to escape.
Still don't think you have explained the problem or even if there is one.
What was the applied voltage coil previously and what was its voltage rating?
What is the applied voltage coil now and what is its voltage rating?
 
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
Me too, I'd sure as hell smoke it if I wired it up...?:huh:

Did you ever meter the voltage when the coil sucked in to see if it stayed a true 480?

No, it had been running in the past when the guys were there. This is a fire damage job and we were hooking it back up to temp power. Most basic starter setup. Motor, starter, pressure switch. No more than 20' of wire from 600 amp feeder to Motor. Not now and not before the fire. Maybe 3' to and from the pressure switch.
 
T

T.M.Haja Sahib

Guest
Measure the impedance of that odd coil applying 480V or 240V AC and compare it with that of the new installed 480V coil.This may reveal the secret,if there is any!
 
Last edited:
Status
Not open for further replies.
Top