compressor shut off question

[Warren Lake]

have the same 5 HP 80 gallon two stage compressor for 36 plus years. Its been good but I burned it out with random orbits and sandblasting. Its loud as its hammering but have used it that way for a while and it works. Know ill buy one or rwo same to replace it.

A month or so ago it didnt turn off, I have it set higher to turn off at 180 PSI for the last 20 years. That helped with sandblasting even though I use a pressure blaster and low pressure. When it didnt turn off I looked for lose wires and tapped the shut off high low thing and then it was fine. After a month of so it stopped turning off again, tapped and no change. I noticed that if I put the Stop button in and turn it so locking stop it just kept running??? that should not be.

Can a start switch get fuzzed up over time and the stop fail? my view is it must have been wired wrong from the start. have to get at it and get some photos. Its off now on the breaker on the panel if I flip the breaker it starts and runs and pretty sure wont shut off. Pretty sure it will do this as well with the stop switch in the lock out position but will check.

Question is logic can the pressure switch over ride the stop switch, logic says no but since I had tapped it past and the thing shut off fine at high pressure I thought id done a fonzie repair.

[Bradley Gray]

pressure switches go bad every day. They are also fairly cheap so might be a place to start.

[Bill Dufour]

Sounds like the contactor is hanging up. Make sure the pressure overload valves are working. I would open up the control box and blow out the dust, exercise the relay and make sure it drops down freely. Probably have rust and crud on the armature. I would pul the armature and wire brush it and the coil inside clean. A gun cleaning brush would be good for the coil interior cleaning.
Could be the contacts are welding shut. Doubtful if they freed up with a tap.
Bill D

[Robert M Richardson]

My guess would be that you have a magnetic starter where the run contacts are held in by a coil which is energized when you hit start and is deenergized by either the pressure switch or the stop switch. They should be in series with each other so if either opens the coil that holds the run contacts releases them and the motor stops. Since neither of these switches stops the motor I'd look at the starter contacts. After 36 years they may be stuck closed for any number of reasons.
Good luck
Robert

[John Pendery]

Pretty much the same thing happened to me last year. Replaced the pressure switch and fixed the problem. Hope that solves your problem as well.

[Warren Lake]

thanks ill try and get to it tonight at least clean out blow out and see. Air conditioner stopped working as well so likeliy post about that usuallyi the condensor goes, its never had any service was working then thought it was a few days later and realized the fan was on auto from the thermostat but the condtioner not running, humidity meter says 94 percent I just walked through a cumulo nimbus cloud. My machines are reporting me for abuse in their living quarters.

[Warren Lake]

fonzi tap worked it stayed locked and unlock ran and shut off on the high as it should. Ill blow that all out and its done its time for sure with few issues other than me burning it out. time to give it some attention but need it to run and work at the moment. Its in a bad place under a stair case with firewood from neighbours apple tree in front. I had looked at the pieces and had a hard time putting them into the wood stove. Compressor box open and ill post in the off topic thread. thanks and yeah it needs some attention maybe it is wired right and always has been just gunked up ill look for a new pressure switch. Past had one brand of electric starters with a number that failed. This is a better brand likelyi Danfoss.

[Bill Dufour]

Pull the pressure release handle and make sure it moves and vents. That is the last safety preventing the tank from exploding and taking out the shop and possibly shoppers. There really should be two or more blowout valves set a few psi apart.
Bill D

[Warren Lake]

thanks thats a good idea plus tank has rust bottom from this too damp place and is older and I run it higher at the 180 shut off good idea thanks

[Bill Conerly]

Maybe time to give it a gold watch and farewell party.

[Warren Lake]

likely time a while ago. ive watched some auctions and just missed a better one customer working me too hard on site and no time to follow it. If I buy new ill decide on one or two same make more sense for future sandblasting.

[Warren Lake]

Actually it did work fine with a tap after testing and shut off on its own and the turn stop switch locked it out and shut off on the second test. Next day it did not shut off on high and stop did not work. Took covers off last night and it sailed past high limit and I ran shut it off at main panel.

That is a good point about the contactor maybe stuck in I actually cant tell even looking at it. Most switches ive manually pushed in wtih a wood block travell approx 1/4" or bit less the didnt even feel ike a 1/16" movement I dont get it. I hope to get the same electrician over later.

In the meantime have sent out feelers for industrial suppliers around Toronto to brampton vaughan Missauga and oakville as i a travel that to get to the customer. Ill do the pressure switch first just based on age then second step if needed. If so be nice if I have a switch in stock as do have several from past not installed new in box will check that here is what the pressure switch is. did see some amazon but rather get it from a compressor place or some industrial supplier.

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[Bill Dufour]

I hope you are not using that pressure switch to switch the load. It is only rated for 3hp single phase so you risk welding the contacts closed. That switch should just switch power to a contactor coil. Let the contactor switch the full load power.
On my compressor I put a small toggle switch on the contactor to turn power on and off to the pressure switch. I did not want it cycling on in the middle of the while I was not home. It sits next to my drill press so it can not come on unexpectedly while using the dp.
Bill D
Bill D

[Warren Lake]

thats the switch that it came with big company 36 years ago. I likely got the contactor mag starter from another company and they told me the wiring. Its been fine used hard 36 years. Ill check what you said or have the electrician later thanks for that info. if its wrong and has welded then that is how long its taken with random orbits and sandblasting this compressor has been tortured. Im tough on machines.

Took him seconds to figure it out disconnected the pressure thing and said turn the power on and it ran, he said it shoiuld not run. I said can we do that with the top button pushed in and he said sure. It ran just the same so contactor welded. I guess it was sticking intermittent. Have to check with a few suppliers now.

[Warren Lake]

called my two main suppliers for a Danfoss and no luck both only have King said no ill keep looking. Likely have to skip woodwork suppliers and go to industrial had one other brand saved past US made.

I think Danfoss not sure maybe last made in Poland. Suspect this one that just went made somewhere else past. Will see when i get it off the machine. Past I did take switches apart file contacts and they worked perfect. Only thing odd time a spring got away on me and across the room and hid in a pile of shavings. Worse than a needle in a hay stack.

Looked on the Danfoss site and cant tell if they sell starters anymore.

[Warren Lake]

With a little luck think ive found the exact contactor and parts for the switch in Danfoss. While not making them anymore told old parts still in stock. this is good if so as I can leave the back of the starter case in place and all the wiring is all cut to length and just re hook up. Number 10 wire ill accept it all cut to length. Contactor and starter and overload may come as parts and I have to assemble and wire.

I was looking at the pressure switch and can replace that as well even if its not the cause. Its wired to the left, is the right side the same set up and you can just hook up to that or is it for another reason. What is the green switch there in between, its sort of spring loaded. When the solenoid went in the truck I was told flip the front bolt 180 degrees and you have a new surface. I got a new solenoid and brushes as it made sense. Is this the same as the solenoid bolt where you get a second chance.

504126

[Bill Dufour]

Probably a two pole switch capable of 240 volts. But only wired for single pole. You can just shift the switched wires over one notch to the right and be using brand new, old stock contacts.
Brushes? you mean contact points?
Bill D

[Warren Lake]

compressor running Elec checked at work their Maint guy and felt its not worth rebuilding. Switch is in works perfectly ill lower the high cut off to put less stress on it. Know im due for a new one or two. Few sell replacement pumps as well.

Bill the contact was the starter motor I was comparing the bolt guys said that I could turn 180. Electrician said he thinks its fine to use the other side of the switch. Said he would have wired it different using both sets but said there are several ways. Service was excellent at the place for the switch parts. They showed me the brand they carry now to replace Danfoss as well. Danfoss got out of making those switches. Nice they had old stock same made in Denmark stuff exact.

[Warren Lake]

used the compressor after the electrician left and 30 seconds in a bang and smoke. Next day Electrician came back and tested said the overload must have tripped and will reset itself but it didnt. Took the contactor apart and the coil had burned Ordered 220 single phase and it was a 110 - 120 coil in it. On the drive there I had a thought drove this far why not buy a second contactor. At the pick up desk diff person served me already paid for first one, asked for a second coil listening to inner voice for a change. He made a face like i was a bother and they were closing soon. Guy came back with a second contactor and cover and said just take them they were sitting in my office and know they dont carry the stuff anymore.

Lucky I asked for that once this coil blew elec took the coil out of the second one and it was proper and all running in some minutes and hoping it stays that way. Company has the correct coil waiting for free. Too my suppliers who said you will never find it and we sell Grizzly a lesson in being Colombo some amount of time it does pay off just takes time. Reason I wanted the same it did 36 years and offshore cant touch that. Second how it was mounted leave the back replace the insides and the number 10 wire all cut to the right lengths and bend a pain to work with so plug and play. All good just took a bit to get there.