Compressor Magnetic Starter meltdown

[Ulma Doctor]

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

 

[hman]

Smokin'!!!!

 

[tq60]

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

 

[westerner]

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....

 

[Gaffer]

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.