[Phatteus]

It is a Model 75SH8 two stage Brunner air compressor with the original tank and possibly the original motor, a WEG 10 HP 220v. (Probably not the original motor. I reached out to WEG for info and was told that this motor is too old for them to have any info on it.)

See attached photos of the set up. It totally works according to the previous owner. He wanted it out of his work space so I purchased it for $140. This unit is heavy at over 1200 pounds. Of course hydro pressure testing the tank is my first priority and replacing blown capacitors on the motor. The inside of the tank has a few inches of oil and water sludge and the sides of the tank are quite rusty. The start capacitor was blowing about every 18 months which is why it was put out of commission.

Interestingly, from what I can figure, and I am no expert, both the start and run capacitors are properly sized for the motor yet two of each are attached in series. Did someone miss wire it at some point or am I missing something? Could this have something to do with why it blows one of the start capacitors every 18 months?

If the tank passes a hydro pressure test that I will conduct with a pressure washer to 300 psi, being sure to remove all air from the tank, then I am considering using electrolysis with sodium carbonate to remove rust from the inside. Then follow that with a good brushing and a rust converter/preventer coating. Or maybe powder coat the interior as a rust preventative and to mitigate hydrogen embrittlement caused by the electrolysis. Or if it passes the test, just use it as is.

All comments and suggestions are welcome. That is, if anyone is interested.

Notice the stack of five full size truck tires sitting next to the compressor. This thing is huge!

 

[sledman8002002]

Welcome to the forum Phatteus!

This thing is huge!

I'll say! Great find for that price IMO

 

[stevon]

Phatteus,

Welcome to the forum and may I say that you got a smokin deal on that compressor! The parts scrap are worth more than that! Addressing your problem, in an electric motor the start capacitor is only used for the first part of initial rotation of the rotor (90 deg) under load. If your start circuit or start switch is closed or has welded contacts the start capacitor will burn up, it is only supposed to be in the circuit for a fraction of a second if the starting system is working properly, the HVAC motor demo in this video explains the principle see:

An electric motor repair shop should be able to help you, I don't think that you need to re-wire the windings, just the start circuit serviced, ask for a quote for that. WEG motors are a good value industrial electric motor company, I used one to upgrade the motor on my compressor

Stephen

It is a Model 75SH8 two stage Brunner air compressor with the original tank and possibly the original motor, a WEG 10 HP 220v. (Probably not the original motor. I reached out to WEG for info and was told that this motor is too old for them to have any info on it.)

See attached photos of the set up. It totally works according to the previous owner. He wanted it out of his work space so I purchased it for $140. This unit is heavy at over 1200 pounds. Of course hydro pressure testing the tank is my first priority and replacing blown capacitors on the motor. The inside of the tank has a few inches of oil and water sludge and the sides of the tank are quite rusty. The start capacitor was blowing about every 18 months which is why it was put out of commission.

Interestingly, from what I can figure, and I am no expert, both the start and run capacitors are properly sized for the motor yet two of each are attached in series. Did someone miss wire it at some point or am I missing something? Could this have something to do with why it blows one of the start capacitors every 18 months?

If the tank passes a hydro pressure test that I will conduct with a pressure washer to 300 psi, being sure to remove all air from the tank, then I am considering using electrolysis with sodium carbonate to remove rust from the inside. Then follow that with a good brushing and a rust converter/preventer coating. Or maybe powder coat the interior as a rust preventative and to mitigate hydrogen embrittlement caused by the electrolysis. Or if it passes the test, just use it as is.

All comments and suggestions are welcome. That is, if anyone is interested.
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Notice the stack of five full size truck tires sitting next to the compressor. This thing is huge!
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[Phatteus]

Thanks for that video, Stephen. I will look into the circuitry to see if it has a start relay. My first thought was that it has a centripetal switch that cuts the start capacitor out of the running circuit but I have not investigated it. Those don't cut the circuit until the motor reaches a specific rotational speed which takes a moment or two. The start relay you pointed out would cut the circuit before even a full rotation of the shaft. It could be that this motor does have a centripetal switch and over the course of eighteen months enough extra current has run through the stat capacitor to blow it? The video you shared shows the start capacitor failing almost immediately due to a bad relay switch. The one on this machine takes eighteen months to blow apart. I definitely have some things to look at. Thanks for the comments and insights.

Do you have any insights about why this motor came with two start and two run capacitors hooked up? Both types of capacitors are properly sized to do the job alone from what I can tell using capacitor sizing formulas found online yet there are two of each in series. I can't make any sense of it so far. Possibly someone replacing capacitors with half sized ones in series and then later someone else replacing those with full sized ones also in series. But then the machine worked as is without issues for eighteen months at a time. I have lots to understand and would appreciate any insights. Especially what size capacitors did WEG originally supply with this motor?

This project isn't so much so that I can have 42 CFM of air. There is no need for that in my garage unless I wanted to blow out all the sprinkler systems on my block at one time! This project is purely for me to challenge myself with a new puzzle to understand and fix. That's my true hobby. And I think the compressor looks cool. If I can't get it working correctly and safely my wife said it would make an interesting lawn ornament. But this machine is destined to keep going. The previous owner says it sounds really cool when on. Not at all like todays compressors. That would be cool to hear.

 

[stevon]

Phatteus,

Yeah this is a nice project for sure, I hope you have at least 200 amp service to your house! LRA of this motor could be 200 to 300 amps from a loaded dead start! That's one reason the lower current start, 3 phase is so popular with these high HP motors at industrial sites. The centrifugal start switch pretty much disengages the contacts before a full revolution. I don't know your particular motor but most AC motors use the same system. That motor is very expensive to replace and if working perfectly quite valuable, definitely worth fixing. The series use of capacitors I'm not sure if that is for aerodynamics (joking) or other reason. I haven't seen any documentation on the 10HP WEG motor. An electric motor repair shop works on all types of motors and can come up with a solution that would work for you, heck filing the contacts or replacing a spring may be all that's needed. it's possible a simple phone call might solve all of your questions. Physics do not change over time so maybe you can get a clue from this motor:

10 HP Air Compressor Duty Electric Motor 215T Frame 1720 RPM Single Ph

10 HP 215T Single Phase 1720 RPM WEG Electric Motor This listing is for a brand new WEG 10 horsepower air compressor motor model number 01018OS1CCD215T, this motor is 208-230 volt, 44.2-40.00 AMPS, 60 Hz, 215T Frame, single phase, 1-3/8" diameter shaft, and 1720 RPM. This motor is specifically...

compressor-source.com

01018OS1CCD215T

good luck!

Stephen

Thanks for that video, Stephen. I will look into the circuitry to see if it has a start relay. My first thought was that it has a centripetal switch that cuts the start capacitor out of the running circuit but I have not investigated it. Those don't cut the circuit until the motor reaches a specific rotational speed which takes a moment or two. The start relay you pointed out would cut the circuit before even a full rotation of the shaft. It could be that this motor does have a centripetal switch and over the course of eighteen months enough extra current has run through the stat capacitor to blow it? The video you shared shows the start capacitor failing almost immediately due to a bad relay switch. The one on this machine takes eighteen months to blow apart. I definitely have some things to look at. Thanks for the comments and insights.

Do you have any insights about why this motor came with two start and two run capacitors hooked up? Both types of capacitors are properly sized to do the job alone from what I can tell using capacitor sizing formulas found online yet there are two of each in series. I can't make any sense of it so far. Possibly someone replacing capacitors with half sized ones in series and then later someone else replacing those with full sized ones also in series. But then the machine worked as is without issues for eighteen months at a time. I have lots to understand and would appreciate any insights. Especially what size capacitors did WEG originally supply with this motor?

This project isn't so much so that I can have 42 CFM of air. There is no need for that in my garage unless I wanted to blow out all the sprinkler systems on my block at one time! This project is purely for me to challenge myself with a new puzzle to understand and fix. That's my true hobby. And I think the compressor looks cool. If I can't get it working correctly and safely my wife said it would make an interesting lawn ornament. But this machine is destined to keep going. The previous owner says it sounds really cool when on. Not at all like todays compressors. That would be cool to hear.