# Compressor Magnetic Starter meltdown



## Gaffer (Jun 9, 2020)

I have a Husky Pro, 7.5 HP, 230V 1PH, 80 gallon air compressor. I purchased it used a couple of years ago. It had meltdown before I bought it, but they fixed it and I've had no issues until tonight. One of the feeds melted down, and what brought it to my attention was that it sounded like the air line at the compressor blew because it was exhausting air at a furious rate. I couldn't find a blown line, but noticed one of the 115v feeds lines was smoking at the connector. I figure it's time for a new one but am concerned why it didn't trip something to interrupt it. I shopped replacements and found prices range from about $170 hundreds more. Mine is a Square D 8911DPS042V09. In the photo, to right, you can see the melting damage from the previous failure. To the left of it is my meltdown. I appreciate any and all advice. Thanks!


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## benmychree (Jun 10, 2020)

What was the full load amps of the motor?  I suspect that the contactor was undersized, maybe the incoming wiring as well.


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## Nutfarmer (Jun 10, 2020)

Could have been a loose or corroded wire where it burnt. Below the contactor are the heater strips so it had over load protection. Think about how many times the compressors cycles on and off. It may have just wore out.


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## mksj (Jun 10, 2020)

Agree with above, it may have been corrosion or loose contacts.
Might check this one out,  $135 with shipping.








						SQUARE D ELECTRIC MOTOR STARTER  8911DPSG42V09 7.5HP 40AMP 208-230V 1-PHASE  | eBay
					

Find many great new & used options and get the best deals for SQUARE D ELECTRIC MOTOR STARTER  8911DPSG42V09 7.5HP 40AMP 208-230V 1-PHASE at the best online prices at eBay! Free shipping for many products!



					www.ebay.com
				




or 3 phase and run a jumper from T2 to L3 for single phase








						SQUARE D ELECTRIC MAGNETIC MOTOR STARTER CONTROL 7.5HP 230V 3PH 8911DPSG23V09  | eBay
					

Find many great new & used options and get the best deals for SQUARE D ELECTRIC MAGNETIC MOTOR STARTER CONTROL 7.5HP 230V 3PH 8911DPSG23V09 at the best online prices at eBay! Free shipping for many products!



					www.ebay.com


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## Bi11Hudson (Jun 10, 2020)

Looks like it failed before and was repaired. If that is indeed the case, I would speculate the starter is too light. That center lug top was obviously loose. Looking to the right, it has been loose before and been jerry rigged once already.

.


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## Reddinr (Jun 10, 2020)

You could also have a look at Automation Direct and replace the contactor and overload and keep the enclosure.  Likely cheaper.   Have a look at  SC-E2S-220VAC  contactor with a  TK-E2-4200 overload.    About $114 I think.     The contactor is three poles but you only need to use two.  Anyway, worth a look to be sure it is a fit.   Based on what is on the contactor you have it looks like the overload is 40 Amps and the contactor coil is 220 VAC.  That is what I based the part numbers on.   Check the dimensions to be sure everything fits comfortably in your box.  You might also find something on Ebay even cheaper.  

I agree with the loose wire theory or maybe burned contacts.  Either one would not trip a breaker.  It would just heat up.


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## markba633csi (Jun 10, 2020)

Undersized wiring and poor crimps, most likely.
7.5 HP that's a bunch of amps
-M


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## Reddinr (Jun 10, 2020)

I think a 7.5HP motor is about 25 or so amps continuous at 230V.  There would be some start-up current for a few seconds above that.  If the CB feeding the thing is 40A, the wiring should be at least 8 AWG.  If it is fed with a 30A breaker then 10 AWG would be safe enough.  However, a 40A breaker and larger wire may be more appropriate to deal with the start-up currents.  A 30A breaker might be just big enough to ride through the start-ups though and cool down between cycles.   If the wires were #10, or even undersized at #12 that is unlikely to be the root cause.  Just a loose connection of some sort or charred contacts.  Those definite purpose contactors are on the quality low-end of contactors in the grand scheme of all contactors.  If it were me, I might up-size the wiring/breaker.  Sorry for getting off topic.  You just needed a new motor starter!


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## pdentrem (Jun 10, 2020)

On the ones that I had to replace at work, it is either a slightly loose at the terminal, undersized and the points burned out. I had one that one of the three contacts was welded together, but it had seen a long service life. Due to the fuse link still intact, it was a loose connection. Crimped wire ends are suggested. 
Just like the old aluminum wiring in the houses, the wire becomes loose over time and heats into a fire. The corrosion that aluminum wire has occurs over time is also an issue. There is a fix for that.
Pierre


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## Gaffer (Jun 10, 2020)

I appreciate the responses. The owners manual called or 10AWG and that is what I ran directly from my panel. I believe the old unit is worn out and likely not treated well in the past. The contacts look bad and the one shows tremendous heat. Should I replace the pressure switch while I'm at it, or is that not an issue?


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## Ulma Doctor (Jun 11, 2020)

the contactor should be a 40 amp 208/230 coil , the overload relay can be 30 amp


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## hman (Jun 11, 2020)

Smokin'!!!!


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## tq60 (Jun 11, 2020)

Have not read all posts but will comment on photo.

Contactor rated just right for motor, no head room.

Get one rated for 10 but be sure it has adjustment for protection.

Wires too small!!!!!

7.5 HP needs much larger than number 10.

Number 10on a 7.5hp motor makes for good heater under load.

Too early to specify wire sizes but others do this in their sleep, seek and take their advise.

Short length of wire is cheap so larger is better and pennies more.

Sent from my SAMSUNG-SM-G930A using Tapatalk


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## westerner (Jun 11, 2020)

markba633csi said:


> 7.5 HP that's a bunch of amps


As alluded to above, it seems to me that wire was undersized, and ANY compromise in connection efficiency was just gonna build heat. 
Do you really need 7.5 horse? Do you own a paint shop? In the world I work in, by the time you get to that amount of power required, they go to a rotary compressor. They accept the fact that the rotary will not make the PSI the reciprocal did, but volume is the issue, and maintenance costs drop after a time. The tire guy is ******, but everyone else is happy....


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## Gaffer (Jun 12, 2020)

It's a beast, but I bought it specifically for my car restorations and to have plenty of CFM for sanding and painting. I've been sitting on a '73 Cuda 340, 4-speed since 1987, and a convertible, '70 Cuda since 1989. Then I got married, had kids, and there was no way I could afford to go through them. I drove both for a couple of years. The '73 was brutal in traffic though. The guy I bought it from built a wicked W2 engine and the clutch gave me a workout. In stop and go traffic it was ridiculous. As for the 70, it's a 318 console car, but the guy I bought it from in San Francisco had converted it to a 440, 4-speed car. The body looked okay, but I'm confident it contains a lot of Bondo. I intend to strip it and fix it correctly. Since it's been cloned, I decided to keep it that way, and over the past 30 years, I have acquired a shaker hood, '70 HP440 long block, a 6-pack manifold, and nearly all of the accessories required to complete the job. The block has been machined by a reputable speed shop and I have all the guts to assemble the short block. I only have to make a decision on the heads and buy the carburetors. Lastly, there's the car I bought in 1983 that I still have. It's not as collectible as the other two, but it's my love affair. It's a 1978 Camaro Z-28. I sold the lousy 350 it came with and the 350 trans in the early 90's with the plan to install a ZZ3. In the mid 90's, I acquired a 700R4 and had it built to handle the horsepower. Due to smog regulations and the world of LS, I'll probably go that route. 

The compressor's owner's manual claims the motor is 7.5 HP and 31 amps. The sticker on the motor says the service factor amps are 36, the wires from the motor are 8 AWG stranded. I'm neither, and electrician or engineer. I've seen no heat damage any place other than what you can see in the photos I've posted. I'm going to replace the starter as recommended above and we'll see how she does.


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