LOW AIR PRESSURE AND POWER TRIPPING

[enzed]

Hi,

I am running a Powermax 45 on a CNC table, cutting into a water pan. At times during cutting, the power unexpectedly trips. When this happens, I have noticed that the air pressure drops to about the lower limit of the recommended minimum of 90 PSI,or perhaps just below it.

Can this possibly be the reason for the power tripping? I would think not? Alternatively, could it perhaps be water splashing onto the T45m machine torch which may be causing an electrical short, in turn causing the power to trip? The water surface ranges from 1" to 3/4" from the bottom of the material.

Any opinions and advice on the cause of this problem and its solution will be very welcome.

Enzed

[urbnsr]

Is your source power enough? I don't think it can be a wet torch. My torch is wet many times and have not had any problems like this. A quick first thing for me is the compressor wants to kick in and while the plasma power supply is running, it's too much load for the circuit. Obviously, I don't know your setup, so I can't say for sure.

How many amps is the circuit able to supply?

Paul

[jimcolt]

Assuming when you say "the power trips"....that you mean your circuit breaker in your AC power panel is tripping. I suspect that you either have a circuit breaker that is weak or undersized for the load. That will not have any effect on air pressure....so not sure what may be happening there. The Powermax unit is an inverter with internal current control. Water around the torch will not change the amperage line draw.

Can you provide info about your power circuit? The size of the conductors, the breaker size, the actual line voltage with no load, line voltage measured while cutting? It would be helpful to measure the current on the power lne with a clamp on ammeter as well while cutting. What thickness are you cutting when the breaker trips?

Jim Colt Hypertherm

[enzed]

Hello urbnsr and Jim,

Thank you to both of you for your responses. I seem however to have found the problem, which actually arose as a result of being incorrectly informed by an electrician.

My initial suspicion when this happened on a previous occasion was an overload of the power supply, resulting in the circuit breaker tripping. But I was informed by an electrician that the circuit breaker can handle the load. So when this happened again, I was totally perplexed as to what could be the cause.

I consequently called another electrician for a second opinion, who attached the necessary testing instruments to the power line to measure voltage and amps before and during the operation of the equipment (as your suggested Jim) and I then I re-ran the system, to cut 1.6 mm (about 1/16") mild steel sheet. What became clearly evident was that when the Powermax is running, and especially at higher amps, and the compressor kicks in at the same time, this results in an overload of the system, leading to the circuit breaker tripping.

So the circuit breaker will be replaced by a suitable one and I'm confident that this will sort out this problem.

Thanks again,

enzed

[sls7474]

You better make sure you have the right size wire before changing the breaker.

[see&see]

When a 5 HP compressor kicks in when you're cutting you need a full 200 amp system along with the proper sized wire..

[enzed]

Thank you for the advice, I agree. I will leave it to the electricity specialists to sort out.
enzed

[jimcolt]

I have a 100 amp entrance (230 volt single phase) in my shop. My compressor has a full load draw of 31 amps (which...if you do the math is as much as 9 HP).....and draws a lot more than that when starting. Circuit breakers with a longer time delay are usually used on high inductive starting loads....not a circuit breaker with a higher trip amperage rating. It has been running for years on a 30 amp breaker.....tripped once on a 20 degree morning before the heater warmed up the shop!

My Powermax85 has been running for 6 years in the same shop on a 60 amp breaker. I rarely cut at 85 amps.....and have never tripped the breaker. Plasma cutters have a high "Inrush" current every time the arc fires. This is actually similar to inductive motor starting loads, but is much higher in amperage but shorter in duration. On larger industrial plasma's (260 to 800 amp cutting power) special circuit breakers with a high inrush rating are often used to prevent tripping.

A 100 amp entrance in a shop with single phase power will support a 5 hp compressor and a Powermax85.....as long as these units are on separate circuits. Also.....you probably cannot run a welder and the plasma cutter at the same time!

Jim Colt Hypertherm

[enzed]

Hi Jim,

This is extremely useful advice; thank you very much. I will keep a copy of these details and will also pass them on to the electrician who will be making the modifications.

Thanks again and best wishes,
enzed