Thread: Power requirement for Mazak QT250

Hi Guys,

I already posted this question in the Transformer/VFD forum but I figured I should ask here as well. Does anyone know the power requirements for a 1998 Mazak QT250. It says 49 KVA on the tag at the back but doesn't list the actual amperage requirements for 230V. It's going to be powered by Phase Perfect 380 which is fed by a 125A line, I know it should have about 200amp input but that's all I could get. The people at Phase Perfect said I'd have 76 amps of 3 Phase with 125amp input. I also have a Haas VF2 that will run off the PP. Would it be possible to run both machines, not balls out, but 50-60% of full load at most.

Cheers

There are a million online calculators out there. A quick figure on one 125amps of 240 3-phase gives you 51kva. 125 amps single phase is 30kva.

I also believe that Mazak says your stuff needs way more than it really does. Had one machine that said 136 amps of 240, ran
it on a 100amp breaker, never blew it. My lathe here, old QT20N, 20hp continuous. Ran that and a Fadal on a 25 and then a 30hp rotary running through
a 60amp single phase breaker. Granted the lathe could only run in low gear and had to set the spindle drive for 5 second ramps.

Your biggest draw is going to be ramp up and ramp down of the spindle. You may need to change that to a second or 2, or more.

Yeah, I had a feeling that number must be some worst case scenario. I mean the Haas has a 20HP, okay 20 Haaspower motor, which is really more like 10-15 and 3 axis drive motors and only needs 40amps full load. The Mazak has a true 20HP motor, 2 axis drive motors and the hydraulic motor. Sure it will need more power than a Haas but double????? I can't see it needing that much. I don't plan on running either machine hard, if I have to I can always shut the other one down.

Originally Posted by Fixed_Gear

I don't plan on running either machine hard, if I have to I can always shut the other one down.

Whether you run the machine hard or not is irrelevant. You will need to slow down the spindle accel parameters like Bobw said as the machine is likely set to accelerate to 120% spindle load on startup. When I did extensive amp draw testing on my machine, the highest load was drawn on spindle start-up from 0 RPM. A little tweak of the accel parameters cut the load about 20 amps, but only took a few extra seconds to reach programmed speed.

Philabuster,

Thanks for the tip. Hopefully I get the thing, then I'll be back to bug you guys how to make that parameter change. Just wondering, in your testing what was the maximum amperage drop you were able to achieve? Was is 20 like you mentioned or could you have gone more? Is there a limit on how far you can adjust the spindle acceleration or is it infinite? Not that I want it to take 15-20 seconds to spin up but an extra 3-5 seconds wouldn't bother me and I doubt I'll be going over 2000-3000rpm very often. Cheers

Not sure about your model, but on my older 1986 Mazak ST25 lathe (25 hp, 2 speed), the spindle accel / decel is controlled by 3 DIP switches on the FR-SE spindle drive itself. The FR-SE manual shows what combination on/off to set them to get the desired accel rate. Mine can be varied from 0.3 seconds to 10 seconds. I have it set at 8 seconds now.

Also, the RPM you will run and the mass of the chuck will GREATLY affect the amp draw on start-up. Big heavy 12" chuck programmed to go to 3000 RPM will take more power to accelerate than same chuck ramping up to only 2000 RPM. A small collet chuck (low mass) spun up to max RPM will not strain the machine nearly like a big chuck. Regardless of the chuck, once the spindle hits target speed, the amp draw falls like a rock.

My PT380 will feed 85 amps then it seemed to limit the current the machine could draw. I changed the accel parameters and I saw about 62 amps max. After the spindle hit 3000 RPM, the amp draw fell to about 15 amps. Machine uses 5 amps when you kick on the breaker (fans and transformer), and uses 11 amps when control is switched on (hydraulic pump runs).

The FR-SE manual says the VFD will regenerate power on decel. The max decel amps I saw was 30 amps, but not sure if that was regenerating the 30 amps or using it. My clamp meter shows only amp draw no way to tell which way the juice is flowing. If I had an old school meter on my utility electrical input panel instead of the stupid 'smart meter', I could easily see if I was trying to spin the meter backwards or not.

Philabuster, thanks for all the information. The lathe has one of those fancy ATS S-20 collet chucks on it but I plan on running an 8" Kitagawa 3 jaw which will also come with the lathe and is also brand new . I can't wait to get my PT380, ordered it on Monday but was told they're back ordered from Phase Perfect and have to wait a couple weeks.

Originally Posted by Fixed_Gear

Philabuster, thanks for all the information. The lathe has one of those fancy ATS S-20 collet chucks on it but I plan on running an 8" Kitagawa 3 jaw which will also come with the lathe and is also brand new . I can't wait to get my PT380, ordered it on Monday but was told they're back ordered from Phase Perfect and have to wait a couple weeks.

The PP is worth the wait.

I ordered mine with the optional 32 character readout (extra $125). The readout is intended as diagnostic tool instead of interpreting the LEDs. The readout cycles the display. First it displays voltage in, then voltage out on all 3 legs, and finally amp draw on third leg for about 10 seconds, then repeats. While the readout is cool, the panel needs to be open and switched on to actually see it.

I plan to cut and install a Lexan window in the door to see the readout without needing to open the door. The refresh rate for amp draw on the panel is not real helpful in watching real time machine loads. I did that with a clamp Fluke meter at the machine breaker. The readings I did get from steady state matched very well though.

As stated in other threads, the PP has no knockout holes for electrical. You will need to drill or punch those yourself. Not a big deal as it made my install look cleaner because I put the holes exactly where I wanted them instead of fighting them.

I also installed an ON / OFF switch in the side per the instructions. Much nicer than playing with the main breaker. However, the PP will still send power through even though it is switched off and not making noise, so make sure you disconnect the breaker feeding the PP before doing any electrical work downstream.

I also believe that Mazak says your stuff needs way more than it really does.

I agree with Bob. Mazak overrates their machines a ton! It's a Japanese thing I believe...

You will be fine with the PP running both machines.

Philabuster,

I got the plasma display as well, I figured for the extra $155 would be worth it. How does one hook up several machines to a PP? Does it have a bunch of terminals in it for say 4 machines or do you have to split up the power after the PP?

I hope to get the Haas hooked up a week or two after I get the PP, I'll have to wait probably two months for the Mazak to become mine .

On the PP website the it shows the unit has a overload current over 4 times the maximum steady state current, I guess for motors starting up and what not.
I sure hope it's going to work for I've already ordered the PP and I sure WANT that Mazak. Once I get everything in I will have to put up some pictures of my shop, believe me when I say it'll be a very tight fit .

For only one machine, you feed directly from the PP. For several machines, you feed the PP into a sub-panel, then wire machines separately on their own breaker of correct size, wire, etc. I picked up my 3 phase sub panel with a bunch of breakers for cheap at my local electronic surplus place.

Tight fit you say? I still have to post pics of my setup. I leaned how to run a shoehorn long before I ran machines. The riggers placed the machines exactly where I wanted them. A few weeks later, I realized I needed to move them as I changed my mind where to put stuff. You would be surprised how easily a 10,000 lb machine can be scooted a 1/4" inch at a time with the right leverage. I moved the Mazak 10" in the nose and 20" in the rear to angle it in respect to the wall. I also moved the 7,000 lb turret lathe 22" with some UHMW feet, a come-a-long and a prybar. The 3,000 lb manual / CNC mill moves easy enough on pipes so that one doesn't really count. I still need to take delivery of a small Hardinge sized HC turret lathe, but it weighs only 1,700 lbs and sits close to the door. Easy enough to place with my engine hoist.