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Cut HP vs RPC HP vs Haas Spindle HP

1032screw

Plastic
Joined
Jan 6, 2020
So I have been a bit puzzled by lack of performance on an old Haas VF1 vertical with 10 HP spindle (shocking I know) and I am wondering if it is just the mill (VFD) or an issue with my rotary phase converter setup. Essentially, I have come close to stalling the spindle when roughing aluminum on not that crazy of cuts. I am finding roughly a a calculated 4 HP cut is running my machine up to 45% load at 7500 RPM (maxxed out). If I start to push past 50% load the spindle will stop keeping up and will lose RPM. I was running last night while doing a roughing routine and walked over to my RPC which shows the voltage on the generated leg. Getting into one of those heavy cuts I am seeing the the wild to line voltage drop from 240V to 228V approximately. That seemed excessive to me.

Next step is to use a meter to monitor current and voltage at the machine but I am am worried the phase imbalance showing as a voltage change is robbing me of horsepower or I have some other problem causing a 10 hp spindle to only be a 4 hp spindle.

My Setup:

North America Phase Converter Co. CP-20 panel (20 HP, 48 amps max, 25 continuous)
Magnetek Century E-Plus E457 20HP 230/460V 3-Phase Type MOGB AC Motor 1745RPM idler motor
100 amp breakers from line panel to CP-20
30 amp breakers from panel after CP-20 to machine.

I have never had issues with breakers tripping but don't tip need to run high loads for a long time as it is a small machine.
 

thermite

Diamond
Joined
Sep 21, 2011
Location
Sol, Terra
So I have been a bit puzzled by lack of performance on an old Haas VF1 vertical with 10 HP spindle (shocking I know) and I am wondering if it is just the mill (VFD) or an issue with my rotary phase converter setup. Essentially, I have come close to stalling the spindle when roughing aluminum on not that crazy of cuts. I am finding roughly a a calculated 4 HP cut is running my machine up to 45% load at 7500 RPM (maxxed out). If I start to push past 50% load the spindle will stop keeping up and will lose RPM. I was running last night while doing a roughing routine and walked over to my RPC which shows the voltage on the generated leg. Getting into one of those heavy cuts I am seeing the the wild to line voltage drop from 240V to 228V approximately. That seemed excessive to me.

Next step is to use a meter to monitor current and voltage at the machine but I am am worried the phase imbalance showing as a voltage change is robbing me of horsepower or I have some other problem causing a 10 hp spindle to only be a 4 hp spindle.

My Setup:

North America Phase Converter Co. CP-20 panel (20 HP, 48 amps max, 25 continuous)
Magnetek Century E-Plus E457 20HP 230/460V 3-Phase Type MOGB AC Motor 1745RPM idler motor
100 amp breakers from line panel to CP-20
30 amp breakers from panel after CP-20 to machine.

I have never had issues with breakers tripping but don't tip need to run high loads for a long time as it is a small machine.

Something is odd. I don't know WHAT, but odd.

I pulled up the maker's page for your RPC. Their specs are closer to TEN HP than 20 HP.

Even with a 20 HP Idler.

Ex:

MY Phase-Perfect (10 HP) and my RPC.. when run AS 10 HP idler.. both want about the same 55-58 A on the 240 VAC single-phase side, and both output much the same @ ~ 35 A on the three phase legs, load side.

Your unit should be capable of higher Amperage, sustained, than the 25 A you cite for "continuous"?

Looks as if the RPC is the limiting factor, but with a 20 HP idler it should not be.

I suspect I'd want to compare the RPC, all parts of it.. to the Williams reference circuit. Wire sizes included.

Or are you citing that Amperage @ 4XX VAC, not 2XX VAC?
 

Strostkovy

Stainless
Joined
Oct 29, 2017
Something is odd. I don't know WHAT, but odd.

I pulled up the maker's page for your RPC. Their specs are closer to TEN HP than 20 HP.

Even with a 20 HP Idler.

Ex:

MY Phase-Perfect (10 HP) and my RPC.. when run AS 10 HP idler.. both want about the same 55-58 A on the 240 VAC single-phase side, and both output much the same @ ~ 35 A on the three phase legs, load side.

Your unit should be capable of higher Amperage, sustained, than the 25 A you cite for "continuous"?

Looks as if the RPC is the limiting factor, but with a 20 HP idler it should not be.

I suspect I'd want to compare the RPC, all parts of it.. to the Williams reference circuit. Wire sizes included.

Or are you citing that Amperage @ 4XX VAC, not 2XX VAC?

I think it depends. If the RPC is designed for a 10 HP load and uses a 20hp idler simply for stability of the generated leg and surge current, then it makes sense to me for the output to be fused for and rated to a 10 HP load. Assuming it is; I didn't look at the specs in depth.

As much as I like running wires for double the amps I'll ever pull, I prefer not to.
 

1032screw

Plastic
Joined
Jan 6, 2020
The panel is advertised as a 20 hp unit. The 25 amp continuous rating might be me reading between the lines a bit as the table I pulled it from lists it as "Optimal sizing amperage". The same table lists 48 amps max capacity at 240v. The mill is rated at 30 amps max load. I guess I need to see what is actually drawing for current.
 

thermite

Diamond
Joined
Sep 21, 2011
Location
Sol, Terra
I think it depends. If the RPC is designed for a 10 HP load and uses a 20hp idler simply for stability of the generated leg and surge current, then it makes sense to me for the output to be fused for and rated to a 10 HP load. Assuming it is; I didn't look at the specs in depth.

As much as I like running wires for double the amps I'll ever pull, I prefer not to.

LOL! Trained since childhood to run at least one size up, so I'm the reverse.

That said, I could see the OP hitting the wall at a 12 HP to 15 HP draw, if-even..

but there is No Fine Waaay he should be struggling at under FIVE HP and running-not-starting load at that.

Something is amiss, here.

It might even be OTHER THAN 'spindle" motor loads within the machine-tool's environment and/or degraded power system components?

EG: Is there a VFD or servo amp inside the cabinet? Does it have capacitors gone aged and leaky, limiting - or even sucking - power that b'long to the load?
 

kustomizer

Titanium
Joined
Aug 17, 2007
Location
North Fork Idaho
I am running a job now in my oldest machine, 97 VFOE, I have to run it @70% feed overide to keep from stalling the 15hp advertised on the front of the machine using a 1/2 em in 6061, the same program will run at 160% overide in my newest machine 30hp I think.
 

1032screw

Plastic
Joined
Jan 6, 2020
Must not be vector drive.

No it is not. The machine is a '95 so pre vector drive. It has a third party VFD in it though the name is escaping me. I want to say Magnetek. It has obviously been replaced fairly recently. Receipts for the VFD were in the cabinet. I bought the machine at auction a few years ago for an outrageously low price. Probably because it didn't look well maintained so I would not be totally surprised if the VFD was not configured correctly.

I think to sum up where I am:

My RPC panel may have been slightly embellished in terms of advertised specs (20 hp) though at a 25 amp nominal capacity and 48 amp max it shouldn't be the cause of the problem. Monitoring current and voltage at the machine input will help verify that.

I should probably crack out the VFD manual and check out how it is set up. Perhaps there is a max current draw or output I am hitting.
 

thermite

Diamond
Joined
Sep 21, 2011
Location
Sol, Terra
No it is not. The machine is a '95 so pre vector drive. It has a third party VFD in it though the name is escaping me. I want to say Magnetek. It has obviously been replaced fairly recently. Receipts for the VFD were in the cabinet. I bought the machine at auction a few years ago for an outrageously low price. Probably because it didn't look well maintained so I would not be totally surprised if the VFD was not configured correctly.

I think to sum up where I am:

My RPC panel may have been slightly embellished in terms of advertised specs (20 hp) though at a 25 amp nominal capacity and 48 amp max it shouldn't be the cause of the problem. Monitoring current and voltage at the machine input will help verify that.

I should probably crack out the VFD manual and check out how it is set up. Perhaps there is a max current draw or output I am hitting.

Magnetek is a Yaskawa brand, one of the older and longer-lived of many.

Generally as good as such things got for "industrial grade" VFD, though whom can even guess how it has fared with the passage of time?

If it is over ten years in-service? I'd start with a NEW one.

Replacement caps are almost ALWAYS more expensive than whole new VFD in today's higher-volume mass-market. ISTR Yaskawa were good for a recommended renewal @ 12 years? After that? "Dice roll". Stacked against YOU!

Nature of the beast. More durable caps want easily twice or more the spend and two, four or more times the volume of living space. Or some trade-off of that general nature... cost/size/longevity balances as they are.

Economy makers go small and short-lived, "industrial" makers larger and costlier, a few, rare, "built like a tank" VFD might go 20 years but ... need space according.

JFDWT as needs and budget permit.

It isn't something you can fight, nor cheaply alter at low-risk, as "capacitance" is only ONE parameter of many when it comes to their selection.
 

rabler

Cast Iron
Joined
May 25, 2020
Location
Rural S.W. Indiana
I was running last night while doing a roughing routine and walked over to my RPC which shows the voltage on the generated leg. Getting into one of those heavy cuts I am seeing the the wild to line voltage drop from 240V to 228V approximately. That seemed excessive to me.

3 phase voltage from and RPC is measured phase to phase (not phase to ground). Typically legs A and B are the incoming legs, and C is the generated leg. So the generated leg has a voltage compared to either phase A, or phase B. To fully report the voltages, you'd need to know both voltage from leg A to C and from leg B to C. Is your RPC giving you both of those and you only told us one of them, or is the RPC only reporting one of those voltages for the generated leg?

How does the Haas calculate load? If it is current through only one phase, that can be deceptive with an unbalanced RPC.

Without knowing what's going on in all three legs it is hard to have a lot of faith in the numbers.
 

1032screw

Plastic
Joined
Jan 6, 2020
3 phase voltage from and RPC is measured phase to phase (not phase to ground). Typically legs A and B are the incoming legs, and C is the generated leg. So the generated leg has a voltage compared to either phase A, or phase B. To fully report the voltages, you'd need to know both voltage from leg A to C and from leg B to C. Is your RPC giving you both of those and you only told us one of them, or is the RPC only reporting one of those voltages for the generated leg?

How does the Haas calculate load? If it is current through only one phase, that can be deceptive with an unbalanced RPC.

Without knowing what's going on in all three legs it is hard to have a lot of faith in the numbers.

The meter on the rpc is a single display and measures voltage from a line phase to the generated phase. I'll have to setup a test cut to be able to see what all the voltages and currents are doing when under heavy load.

I will also have to see how the Haas measures load. I am not 100% sure it is used but the VFD can output either an analog signal relative to current load or power level.
 

1032screw

Plastic
Joined
Jan 6, 2020
Magnetek is a Yaskawa brand, one of the older and longer-lived of many.

Generally as good as such things got for "industrial grade" VFD, though whom can even guess how it has fared with the passage of time?

If it is over ten years in-service? I'd start with a NEW one.

Replacement caps are almost ALWAYS more expensive than whole new VFD in today's higher-volume mass-market. ISTR Yaskawa were good for a recommended renewal @ 12 years? After that? "Dice roll". Stacked against YOU!

Nature of the beast. More durable caps want easily twice or more the spend and two, four or more times the volume of living space. Or some trade-off of that general nature... cost/size/longevity balances as they are.

Economy makers go small and short-lived, "industrial" makers larger and costlier, a few, rare, "built like a tank" VFD might go 20 years but ... need space according.

JFDWT as needs and budget permit.

It isn't something you can fight, nor cheaply alter at low-risk, as "capacitance" is only ONE parameter of many when it comes to their selection.

It is a magnetek vfd. From the receipt in the cabinet it was replaced in 2009 so maybe it is time for a new one. Luckily I have the manual for it as well as the list of parameters Haas used if it needs replacing. It is supposed to be a 7.5 hp drive with the max current bumped up from a factory set 20 amps to 26 amps per Haas settings. I guess I can see if I am actually getting that to the spindle.
 

thermite

Diamond
Joined
Sep 21, 2011
Location
Sol, Terra
It is a magnetek vfd. From the receipt in the cabinet it was replaced in 2009 so maybe it is time for a new one. Luckily I have the manual for it as well as the list of parameters Haas used if it needs replacing. It is supposed to be a 7.5 hp drive with the max current bumped up from a factory set 20 amps to 26 amps per Haas settings. I guess I can see if I am actually getting that to the spindle.

I wasn't clear. Magnetek VFD have never NOT been Yaskawa/Magnetek product.

And that is a feature, not a bug. Yaskawa do good VFD. That's why at one time MANY others re-branded them.

Even so, under powered for the load is exactly what it says it is.

OVERkill is far better for lesser operating STRESS.

Just not by so much the feedback sensitivity is too damned coarse for good regulation.

And Yes, it is time for a new one. VFD do not last "forever" like DC Drives can do. They have a harder job to do. CREATING a complex wave form. Not just switching an existing one delivered ready-to-use off "the grid".

Avoidable downtime is no more "free" than time wasted getting started at earning MORE MONEY is "free". Good gear, run wisely and well, pays for itself, and not-only. Excess frugality and starvation are first-cousins.

Heard it on the radio.

Guy said his wife was always going about wringing her hands and saying
"Oh, frugal me!"

So one day he honoured the call.. and frugaled her!

Guess you'd have to ken "priorities?"

Or maybe just prefer SE grins to chronic whining?

:D
 

CITIZEN F16

Banned
Joined
May 2, 2021
Is your converter balanced properly for your machine? Measure A to B, B to C, and A to C, what do you get? Measure under load, and unloaded. It might need some tuning.
 

1032screw

Plastic
Joined
Jan 6, 2020
Is your converter balanced properly for your machine? Measure A to B, B to C, and A to C, what do you get? Measure under load, and unloaded. It might need some tuning.

I thought it was but I am honestly not 100% sure. The machine wants 240V +/- 10% with its current config. So 216V to 264V. The limiting factor is the generated phase to other phase voltage since it varies depending on load on the RPC. Right now at idle with the machine powered on that generated phase to line phase voltage sits at 260V so not much margin. As previously stated that same voltage under the max load the machine can currently sustain I was seeing something between 225v to 230V. So plenty of margin on the low end. My understanding is if I wanted that under load voltage to come up I would be pushing the idle voltage up as well which I don't really have room to do. Is my understanding correct?
 

1032screw

Plastic
Joined
Jan 6, 2020
I did some testing on this issue and I think I am running into a max torque issue. VFD is set per factory setting. I set up a test cut in 6061 to work the machine while I checked current draw.

3 flute 1/2" End Mill
1" DOC
.1' R DOC
7500 RPM
.006 IPT / 135 IPM

The machine could barely make the cut. Lost RPM along the way Spindle load meter when over 100%. Max current draw at the input was 26 amps.

Interesting thing is I backed the RPM down to 6000 RPM during testing and was able to push feed to 120% so 162 IMP and the spindle wasn't having any issues keeping up. Overall a higher MRR than where the test cut started. I suppose it still could be a tired VFD but it kind of seems max HP is not at 7500 RPM and that is my issue.
 

JST

Diamond
Joined
Jun 16, 2001
Location
St Louis
Check the manual. A quick look at specs showed that max torque seems to be at 2k rpm.

That's not unusual, depending on how they have the motor and drives set up. Overspeeding the motor when you "run out of Volts" leads to decreasing torque as speed increases.

You might need to see if you can determine what the sweet spot for material removal is, vs cutter size, finish quality and other things.
 

mmurray70

Hot Rolled
Joined
Jan 11, 2003
Yeah what you are describing is just the nature of over speeding motors with vfds. My Fadal is same way. 10hp motor but I can barely make a 4hp cut at 8000 rpm.

The load meter on mine isnt that advanced at all, just measures vfd current, so max load at high rpm is when meter shows like 30-40% or something. Sounds like yours is the same.

Just get used to optimizing roughing at lower rpm, make the best of the machine you have. Use the higher rpms for finishing and smaller tools.
 








 
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