Running a small cnc mill on a generator

[0jw]

Hello everyone, I'm hoping to find a bit of advice on this so I don't blow my machine up.

I have a pm727 converted to cnc useing dmm dyn4 drive and 750w servos. All 3 servos are on one 40a line filter for power and a 30a line reactor on 40a 240v breaker.

The spindle is a marathon 1.5hp 3 phase useing a teco E510 vfd. The vfd has a 20a line filter and is on its own 20a 240v breaker.

I have a champion 100155 dual fuel generator. It's 435cc 9kw starting 7kw running. It's claimed to be a 5% THD (total harmonic distortion) unit.

I've noticed when welding with the generator on 120v there is a long lag going on as the engine revs up. So I'm concerned about running the machine on it.

Should I consider adding a capacitor bank to the system for power factor correction? I know this is done with phase converters sometimes for balancing.

I thought about splitting the load so the spindle is not on the generator.
The alternative is running 500 ft to a new sub panel.
Any suggestions or experience with this is greatly appreciated!

 

[ultraguy]

Hello everyone, I'm hoping to find a bit of advice on this so I don't blow my machine up.

I have a pm727 converted to cnc useing dmm dyn4 drive and 750w servos. All 3 servos are on one 40a line filter for power and a 30a line reactor on 40a 240v breaker.

The spindle is a marathon 1.5hp 3 phase useing a teco E510 vfd. The vfd has a 20a line filter and is on its own 20a 240v breaker.

I have a champion 100155 dual fuel generator. It's 435cc 9kw starting 7kw running. It's claimed to be a 5% THD (total harmonic distortion) unit.

I've noticed when welding with the generator on 120v there is a long lag going on as the engine revs up. So I'm concerned about running the machine on it.

Should I consider adding a capacitor bank to the system for power factor correction? I know this is done with phase converters sometimes for balancing.

I thought about splitting the load so the spindle is not on the generator.
The alternative is running 500 ft to a new sub panel.
Any suggestions or experience with this is greatly appreciated!

You're going to be dealing with all the fumes and fuel and electrical issues every time you run the machine, plus the noise.

You could opt to do what I did and that is build an extension cord long enough to reach the sub panel if it's existing. Just add a welding plug on the panel and plug in the cord when you want to use the machine. There is also an added benefit of being able to deliver a lot more high quality juice to where you're working by using larger breakers and a beefy cord.

I have 150ft of SOOW 600v cord cable tied to the wall running from a plug that I just plug into my 3 phase 600v outlet when I want to use the machines.

 

[Freedommachine]

You should be fine on a generator that size. The nice thing about vfd's is the ability to change the ramp up / down time when turning on / off the spindle motor. This will reduce the large starting load and give the generator time to keep up. I don't know that adding caps before the vfd would be a good idea.

 

[0jw]

Thank you. I had came to somewhat of the same conclusion about slowing the ramp speeds. Probably a good idea for the servos also. Although I don't go over 400 Ipm.

Looking into it more I think for piece of mind it would absolutely be worth upgrading to something like a mep-803a.

 

[gustafson]

Have a braking resistor for decel

Worst case it is probably like running on a phase converter, if you pull too much startup current, voltage to the control drops and trips it out


Maybe worst case a PC sized UPS for the control, assuming it runs on 120v

 

[0jw]

Unfortunately while the power is there, it looks like the outlets don't support it.
It has 4x 120v 20a gfci, 1x 120v 30a and 1x 120v/240v 30a.

The dyn4 take ac in and can use 120v 240v 1ph and 300v max 3ph. Although I don't think it's the best option with the 750w motors.

I have some dyn2 drives that run on a meanwell dc psu and can run the 750w at 1/2 speed. It has an active voltage sense for regulating the DC output And I believe already has substantial filtering built-in. So that might be a good option.

 

[0jw]

You're going to be dealing with all the fumes and fuel and electrical issues every time you run the machine, plus the noise.

You could opt to do what I did and that is build an extension cord long enough to reach the sub panel if it's existing. Just add a welding plug on the panel and plug in the cord when you want to use the machine. There is also an added benefit of being able to deliver a lot more high quality juice to where you're working by using larger breakers and a beefy cord.

I have 150ft of SOOW 600v cord cable tied to the wall running from a plug that I just plug into my 3 phase 600v outlet when I want to use the machines.

Sorry for the late response. I'm not sure if you mean to be running single phase or 3 phase through the extension. I don't think I won't to linking 4 150ft chords together. But if I did I would probably want to do anything I could to lower the amps.

 

[CITIZEN F16]

I would just make sure you are getting steady, within tolerance power through the control circuit. If you are going to use extension cords make sure they are sized correctly to prevent an excessive voltage drop. Once you got everything hooked up do a nice long dry run to look for trouble. Some electronics have no issues being run of generators, others do. I have a friend who has a high end espresso maker that refuses to run off his generator, but his PC will.

 

[Phil in Montana]

Dont do it, you have a made in China p o c generator. very poor volt reg, if you had a quilty 10 kw set maybe but not a air cooled 3600 rpm china job. just wire in the power from the house...Phil

 

[CITIZEN F16]

I thought about splitting the load so the spindle is not on the generator.
The alternative is running 500 ft to a new sub panel.
Any suggestions or experience with this is greatly appreciated!

The spindle is the component least likely to have issues running off a generator.

 

[0jw]

I'm trying to decide if this is necessary to buy an oscilloscope to check the output of the generator.

I see a lot of people simply just checking the waveform with old scopes.
From what I understand I should be checking it with a scope that has FFT function to get the THD.
I don't know much about oscilloscopes, but I understand that it needs to be floating like a portable unit and probably need a 10x or 20x probe so it's within the input range.

I forgot to mention that it's not an inverter generator. Just alternator. So I'm concerned about the motor governor.
I've seen a lot of conflicting opinions about both types. But from what I've seen and I may be wrong, I don't think the bigger diesel generators are inverters.

 

[0jw]

Dont do it, you have a made in China p o c generator. very poor volt reg, if you had a quilty 10 kw set maybe but not a air cooled 3600 rpm china job. just wire in the power from the house...Phil

Yeah, I can see how the power demand will ramp up the governor and mess with voltage and frequency.

I'm hoping to get a mep-803a Diesel military genset. But had also considered hooking up a pto generator head to my Stepvan. It's a Detroit Diesel fuel pincher.