POWERMAX 45 ARC-OUT WHEN COMPRESSOR KICKS IN

[enzed]

I have been using a Powermax 45 via a CNC system (driven by Mach3) for some time with practically no problems. Recently however, a problem has appeared, the source of which I cannot find and will be very grateful for any advice. The problem is as follows:

After cutting for a short time and as soon as the compressor kicks in for the first time since the start of the cutting process, the arc cuts out immediately and the gantry also stops moving. Air continues to pass through the torch and only stops when 'Stop' in Mach3 is clicked. The power supply (220V) does not trip when this happens.The compressor kicks in at 6.5 bars (94.3 PSI). Is this perhaps too close to the cutter's lower limit, triggering a shut-down in the cutter? Other compressor specs are: 3HP(2.2kW), 13.7A and 8.8 CFM (250l/min).

I have had an electrician check for earthing problems and loose connections but none were found. The compressor voltage was also checked before the compressor kicks in and during its run. This drops from 228V to 218V. Could this drop of 10V perhaps be the cause of the problem, i.e. that the cutter senses the drop in voltage and cuts the arc?

I also disconnected the computer and replaced the machine torch with a hand torch. When the compressor kicked in while I was cutting, the arc also died but re-pressing the trigger again re-activated the arc, indicating that the cause of the problem is not due to a computer or software fault. As with the machine torch, air continued to flow during the arc-out.

An engineering friend suggested that it could perhaps be the compressor motor condenser which may be faulty (even though the motor appears to start and run normally), and which causes a power spike, in turn triggering a shut-down in the Powermax. Could this be the cause?

I will be very grateful for any comments and advice as I am at my wit's end with this problem.

enzed

[jimcolt]

Install a pressure gauge hard plumbed at the inlet to the plasma (it will not be accurate if anywhere else on your system). With your compressor at its low pressure point activate the air flow at your torch by turning the amperage knob fully CCW. You will see the newly installed gauge pressure drop....and if it drops below 90 psi than there is your issue. You may need to increase the minimum pressure on your compressor by adjusting the on / off cycle switch. Jim Colt Hypertherm

[enzed]

Wonderful, thank you very much for the advice Jim. I will report back on the results so that others can also learn and benefit from this problem.

Just one point I'm unclear about however: Must I activate the air flow at the torch by turning the amperage knob CCW when it is cutting, or when it has not been activated to cut but with the Powemax 'on' (live)?
enzed

[see&see]

I have had an electrician check for earthing problems and loose connections but none were found. The compressor voltage was also checked before the compressor kicks in and during its run. This drops from 228V to 218V. Could this drop of 10V perhaps be the cause of the problem, i.e. that the cutter senses the drop in voltage and cuts the arc?
enzed

Low air pressure is usually the problem as Jim pointed out. But the coincidence of losing arc at the exact time the compressor starts brings up some possible inrush current issues starving the cutter of necessary operating current as you stated.

Does the voltage drop from 228V to 218V with the motor constantly running or is that only on startup? At 218 volts the motor can handle the work but you are getting down to the lower limit of useful function to operate the compressor. Also a constant drop to 218 volts running the compressor tells me the wire gauge in the run from the transformer is to small or it's aluminum wire.

The instantaneous peak current measured in micro seconds at motor startup can reach 4 to 10 times the amount of current needed to run the motor normally. A normal current or volt meter won't reflect the actual peak inrush current or startup voltage drop.

At this point everything comes into play, distance from the power company transformer to your shop, wire size/gauge and type of wire etc. A good clue is if the lights in the shop flicker or dim when the compressor starts the electrical current available could most likely be the problem.

[beefy]

Don't suppose you have any friends that could lend you an Uninterruptable Power Supply. If momentary voltage drop is what's causing this, then a UPS may be the cheapest fix.

An electrician will need to do more than just check the voltage with the compressor on and off. He'd need to have some test instrument that can record the momentary voltage drop when the compressor motor kicked in, and see how bad it was.

[enzed]

Hi see&see and beefy,

The voltage drops from 228V to 218V and stays there while the compressor is running. And the wiring and distance to the power supply transformer have not changed. So If the cause of the problem is the quantity and quality of the power supply (as it seems to be, from what both of you are saying), then this would make sense as the problem is a new one; everything worked perfectly a month ago.

And yes, the lights in the workshop do not flicker but dim noticeably for a split-second when the compressor kicks in.

See&see, you say "The instantaneous peak current measured in micro seconds at motor startup can reach 4 to 10 times the amount of current needed to run the motor normally." Would a faulty motor condenser on the compressor contribute to the problem, even though the motor appears to start and operates normally?

Regarding a UPS, I unfortunately do not know anyone having one. The electrician however did suggest the installation of a device to regulate voltage, which may be the solution, but I do not know enough about electricity to agree or disagree with him.

enzed

[see&see]

beefy,

If the start capacitor on the motor was bad it would not start at all..

I was just thinking about this, you could have a stuck unloader valve on the compressor. Some compressors have them and some do not but what the unloader valve does is unload the pressure on the piston when starting up and the motor does not work hard at all to come up to speed. Once the motor is up to speed the valve closes and the pump makes air. If you don't have an unloader valve contact the compressor manufacture and find out if one is available..

I have a 5 HP vertical MATCO compressor in my garage at home and it does not have an unloader valve. My voltage in the house garage is 243 volts most of the time and the compressor starts instantly and runs at around 240 volts. We had a power outage a few years back and I power the house with a 12 KW Hatz diesel generator. With almost nothing on in the house using the generator it will not spin up my compressor.. Just sits there and hums with the generator at full load.. If I disconnected the line to the tank check valve from the pump I'm sure it would spin up easily using the generator.. That generator will power the whole house easily but will not spin up the compressor under load due to the large inrush of current required.

[beefy]

See & See,

good one about the potential of the unload valve causing a heavier than usual load.

Enzed,

the two voltage levels with the compressor running and not running are just the steady state levels. The bit in between is where the problem MAY lie, i.e. when the motor starts and the voltage takes a very short but significant dip. I'm guessing this is affecting the PC and it turns off the torch and stops motion.

When I suggested a UPS I meant for the computer only, sorry if that was not clear and you thought something else. You can get them at various electrical/electronic goods type shops.

Unfortunately this is just calculated guesses so please don't hate me if you buy one and it doesn't fix the issue

Possibly a cheaper "attempt" at a solution is to get a quality PC power supply. Maybe they can handle the momentary interruption in the PC power supply and it will fix things ??????

You know what, I'd even think about joining some electrical forum lack "Stack Exchange" where lots or pretty knowledgeable guys hang out. Whenever I have a specific problem, I look for related forums where guys jobs are related to the problem at hand.

[enzed]

Hi again.
I tired Jim's suggestion but that made no difference. I forgot to mention that the Powemax is "hard plumbed" with a pressure regulator, gauge and water trap at its backside.

Regarding the computer possibly cutting out, this does not appear to be the problem as I tried to cut with a hand torch after I disconnected the Powermax from the computer and the same thing happened - as soon as the compressor started, the arc died simultaneously. But unlike the CNC, I re-pressed the torch trigger and continued while the compressor was pumping up. But getting a UPS is a good idea, and I certainly will not hate you beefy; I'm only too grateful that you and see&see have taken the trouble to try and assist me, and for your detained replies!

The stuck unloader value is something new and could possibly be the cause of problem, or contributing to it. When I switch off the compressor on the pressure regulator switch, I hear air blowing for about 1-2 seconds, like something being deflated. Why would this happen only when I turn the switch to off? Other than this, I don't know what an unloader valve looks like, or where it is located. And as for the manufacturer providing advice, this is Chinese compressor, in which case I guess that it will be very difficult to get any advice from them. But I can try with the agents, and compressor repair companies.

And thank you also for the suggestion about getting specialist advice from electrical specialists, I will certainly follow this up with them. I have meanwhile discussed my problem with an electrician who said that he will check the power supply from the transformer to the house, and we'll take it from there. When the problem is hopefully found and fixed, I will let you all know what it was.

Thanks again,
enzed

[beefy]

Aahh that makes a lot of sense now. The plasma cutter seems to be what is being affected by the voltage drop and it shuts off. Then of course the Arc OK signal is gone and the cnc controller halts motion (assuming THC was enabled).

Might also be worth telling this to Jim in the Hypertherm section and see if he has any feedback about your plasma cutter model and what sort of momentary voltage drop may cause this. Is this getting to the chicken or the egg scenario ? Has the voltage changed or has something changed in the plasma cutter ??

Anyway, hope you get it all sorted.

Keith.

[see&see]

It's normal for the unloader valve to exhaust air for a few seconds when the compressor shuts off so that's unlikely to be the problem.

Most of the time low voltage problems don't show up until the motor burns up due to running at over the temperature limits. And that's almost always caused by low voltage supply. Out on a job a contractor burned up several small electrical pumps in a week using an 100' 14 gauge electrical extension cord. I loaned them my 10 gauge 100' cord and the next pump lasted a month until the job was done. The big box china 14 gauge cords are always cheaper and the skill saw/electrical tool sellers love those cords..

Here's a link to a voltage drop calculator page that is real handy to calculate distance and voltage drop with any type of wire.

http://www.calculator.net/voltage-drop-calculator.html

[acourtjester]

The unloader valve is to remove line pressure between the compressor and the tank normally this is so the compressor starts without pressure so it starts load free. If you look at the line to the tank you may find a small hole in the fitting that is where it unloads. The better compressors have a mechanical on the compressor with a small line for the discharge.
https://www.grainger.com/product/4X997? ... adType^PLA

[sphurley]

There is also a check valve at the tank. They go bad a lot. On lower cost compressors the release valve is just a quick release at the end of the cycle.
If the check valve leaks then the compressor starts up against the pressure. Pop out the check valve, it will look like a brass fitting going into the tank. Clean it up and see if that helps.

[sphurley]

https://www.youtube.com/watch?v=pduPuJ9k9Bw

[enzed]

Hello everybody,

Thank you so much for your comments and advice and the web links, I really appreciate it. I doubt very much that it is the Powermax that is faulty, but will take it up with Jim as you suggest beefy. Most likely a power supply problem and/or a fault with one of the compressor valves. We have been having a lot of power supply problems lately, so this is something which I need to have inspected again very carefully by an electrician.

enzed

[jimcolt]

Borrow an adequately sized generator and run either the plasma or the power supply separately. If everything starts and runs fine then you need to get an electrician to come determine where your power problem is occurring. Jim Colt Hypertherm

[Old Iron]

A bit of thinking outside the box, so to speak.
The transformer outside your shop may be marginally too small to carry the load. Since your voltage drops by 10 volts then it is taxing the transformer.
Wire size coming from the transformer into the shop may be too small too.
When the power company came out to install a new pole, they said that was the case at my place. They changed out the transformer at no expense to me.
Another thing to check, is the compressor and Powermax on the same circuit? If so change that too.

[enzed]

Thank you Jim and Old Iron, I will do so.
enzed

[enzed]

Hello everybody,
As I promised to do at the start of this posting, I am reporting back on the cause and solution of my problem with the Powermax 45’s arc switching off when the compressor kicks in, so that my experience may be of benefit to others who experience a similar problem in the future.
I am very relieved to say that my problem has finally been solved!
As some of you suspected, the cause of the problem was a power starvation problem and not any fault with the compressor, as was also suspected. With the assistance of an electrician, it was found that when the Powermax was cutting and the compressor kicked in, the voltage dropped from 228 to 209.
So it was consequently decided to replace the wiring – the main cable from the house to the garage (a distance of about 12 m (40 feet), as well as the wiring from the circuit-breaker unit to the cutter and compressor. This was replaced with thicker wiring (6 mm – ¼ inch). In addition, the power supply to each of these machines was separated from the circuit-breaker unit, and each was provided with a 60A isolator switch.
Since these upgrades were made, no more problems with the cutter arc switching off when the compressor kicks in!

Thanks again to all who provided advice and guidance.

enzed

[Creative25]

I read this post with great interest and recognized immediately. Because I have exactly the same problem.

Our local power company is a disaster. And I have exactly the same problem.
When I just switch the compressor on voltage drops to about the same as yours.

If I cut at 45 amps voltage drops to about 180v at about 17“ volts the plasma cutter cuts out. Air keeps coming to cool the torch. That is quite neat so it saves my consumables.
Cuts out at random depending on how much power my neighbours are using. I found the plasma cutter runs reliable at 35 amps when the compressor kicks in torch goes off and program poses. So I have to wait until the tank is full and the compressor goes off.

I checked out the voltage drops and it is actually the wiring from the transformer to my house.
The transformer is 500meters away from my house.
It is a 100kw transformer and there are about 30 houses connected.

I contacted the utility company asked them to upgrade the system. There is a main line going close to our neigbourhood. The answer I got is this. It is impossible to overload a 100kw transformer. And it is impossible to overload the main line that connects to the houses. Obviously they don’t know what they are talking about.
So they offered me two things connect me to a different phase with less load on it. Or stepping up the voltage.

So they changed the phase. Now voltage is more stable but still the same voltage drop.

So basically the 60 amp connection can only supply 10A without significant voltage drop.

When I complained again they said I should get a three phase connection. But what does it help if I have 3x 10 amp in my house??
And have to spend lots of money for it.


So basically I can forget about reliable electricity.

I thought in the long run it would be nice to have a large solar system that can run the plasma cutter and run the compressor on utility power.

But for now I am looking for an affordable work around.
So far I have been thinking of two options.

Get some extra air tanks maybe gas bottles.
The other option convert the compressor to run with a gas driven engine.

Is there anyone who has the same type of problems?

What solution would you recommend?

[adbuch]

Either one of those 2 options sounds like a good solution. If you power your air compressor with a gas driven generator, then assuming that you size your generator correctly - it should work well for you and also give you a backup power source in case your local electrical grid goes down.

Having additional storage tanks connected to your compressor is a good idea as well. This will let you cut longer between compressor on/off cycles.
The option to use compressed gas bottles (if that is what you mean) would require an appropriate pressure regulator or flow meter to step down the several thousand psi in the gas bottle to the 100 psi you need for your cutter. Also, you would need to continually take these gas bottles to have them refilled.

Another option might be to monitor your air compressor air pressure and figure out a way to pause your cut when the compressor tank pressure is just about low enough for the compressor to come on. Then drain out some of the air to force you compressor to cycle, and then when it turns off resume your cut. If this is a hobby with only occasional use, that might be a workable solution.

David

[Creative25]

Thanks for your reply.
As far as gas bottles goes.
I would use empty propane bottles for extra air storage.
I just wonder if you could control the compressor with linuxcnc. Have an electric unloader valve. And start the compressor with a relay.

[adbuch]

Thanks for your reply.
As far as gas bottles goes.
I would use empty propane bottles for extra air storage.
I just wonder if you could control the compressor with linuxcnc. Have an electric unloader valve. And start the compressor with a relay.

I was suggesting that you monitor the air pressure, and when it drops to a level just before the compressor would normally turn on - pause your cutting and let enough air out of the air compressor tank so that the air compressor turns on. Then when it turns off, resume your cutting. I don't know that it matters how you do this. You could use a solenoid valve to let the air out of the tank until the compressor turns on. There are many ways I can think of to do this, depending on how elaborate a scheme you want to use.

Once the air pressure drops to the cut-in pressure the compressor is set at, it will turn on by itself - so no need to start it with a relay.

David

[Creative25]

Yes I understand this would also work. Somehow I would like it to stop at the end of a cut. I will post on the linuxcnc forum to find out what is possible.
Thanks for your idea.
What kind of pressure sensor would you suggest?

Do you have something in mind?