CNC LATHE

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I have a new hurco lathe has no electrical specs and tech at factory repeated name plate: Largest motor 25 kva 36 amp, fla 60kva 150amp. The owner says its 16000 rpm and 47Hp at spindle. My question is ,have the motors and total loads calculated at 150amp is there any other calculations necessary. There is a handle on a device that looks like a disconnect at the control panel and it accepts the line side three phase wires and its rated at 150 amps by partial label on device. also if 150 amps is full load the disconnect at gutter tap would preferably be a 200amp 3 phase disconnect with 150 amp fuses to give best current limiting over current protection. Is this machine calculated already and will never see the FLA? Wire size 1-0 at 60" and 150 amp fuses? Thanks any additional advice would be appreciated. I am currently on this thread 1-15 2013 @10 51pm tejas time GOD BLESS ,and thanks for your time
 
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pfalcon

Senior Member
Location
Indiana
Machine tools are a closely related but different beast than normal electrical wiring.

Although it sounds like you've found the disconnect, it also sounds like you're not sure it's the disconnect. You should find someone familiar with working on machine tools before continuing to pursue this. There are some strange high-energy devices that can be present inside that panel. A qualified person should be able to pull the brand and model number off the disconnect to look it up on the web.

Specifically to the nameplate question: The FLA on the nameplate is the highest current the line-side of the disconnect should see under normal use, not prolonged use. It's supposed to include special or unusual currents under some circumstances. The machine nameplate is also required to repeat the largest motor's nameplate information. That motor may never see those amperage values during normal use.
 
main disconnect for CNC Lathe, Fuse or Circuit breaker? with Fuses at main disconnect

main disconnect for CNC Lathe, Fuse or Circuit breaker? with Fuses at main disconnect

I hope this is not to confusing my dilemma is the fuse vs circuit breaker for CNC lathe disconnecting means and straight up 150amps due to manufactures calculations ( choice of circuit breaker per owners budget, I told him time delay fuses open in less cycles). I'm delivering the power to the lathe, I could not get any specs on this for its new and nothing on the manual about line (power source and disconnect) the tech person said its 145 amp ,and 58 kva > full load amps =150 amp and to use fused disconnect. IF I go by the manufactures name plate as full load amps of 150 amps ,60kva / 398 =150.75 is there should not be any further calculations for the fuses for supply?, or is 150 amp gospel by manufactures nameplate and my responsibility is to deliver 150 amp supply , I hear what your saying about it'll never see this amperage due to intermittent starts and other equipment . In this shop of 50 or so CNC lathes I have yet to see one fuse-able disconnect to any individual motor( per last electrical co. with Challenger panels and breakers). The 150 amps that I propose to install will tapp off a gutter that feeds 2 panels, the main power source is a 200 amp fuse able disconnect tapped from gutter then fed from meter,selective coordination over current device (200 amp 3 phase fused disconnect should have current limiting fuses,therefore the gutter down line would be ok with a circuit breaker disconnect for the 150 amp lathe. I have eliminated one three phase panel to accommodate the 150 amps due to machines not being used. My question is the current limiting and quick action of the fuses more favorable at the power source and down line, or is it not necessary due to selective coordination(main 200 amp 3phase disconnect with fuses).. the gutter that will feed the 150 amps already has a 200 amp fuse-able disconnect feeding these panels so circuit breaker is acceptable? Thanks fore the sound board and any advice on the supply power source and disconnecting means. If its confusing I'm tired and will check before bed or morn if anyone can give some solid advice
 

jim dungar

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Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems
My question is the current limiting and quick action of the fuses more favorable at the power source and down line, or is it not necessary due to selective coordination(main 200 amp 3phase disconnect with fuses).. the gutter that will feed the 150 amps already has a 200 amp fuse-able disconnect feeding these panels so circuit breaker is acceptable?

You will only achieve complete coordination if you have a minimum of a 2:1 ratio between upstream and downstream fuses. You can achieve basic coordination (e.g. coordination for overloads vs short circuits) just by the nominal size of the fuse.

Without any other input I would be using Time Delay Class RK1 fuses for the feed to an expensive 'electronic machine' like a CNC.
(Look at Bussman LPS-RK, Merzen A6D, or Littelfuse LL-SRK). Although after a little more research, I would not be surprised if the CNC manufacturer would accept a less expensive Class RK5 (FRS-R, TRSR, and FLSR respectively).
 
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CNC Lathe Discription

CNC Lathe Discription

name plate ac volts 3phase 400, foreign ? this is a name plate on top of the name plate with a hole punch like they put the wrong plate over a sequence of numbers, at the bottom it has 230 volt 3 phase . Owner and tech who will be starting up the CNC,say that the spindle motor is 47 HP. the name plate says 25 kva 36 amp. A 50 amp 230 volts 3phase is 130 amps so is the 47 a total of mtr loads , told to him or is he being mislead, because I,m not seeing it. The tech saw the name plate and could not explain the discrepancy he said talk to the Hurco rep. the rep said 58 kva with options (430-22a ). The disconnect handle is mounted to a main rated at 150 amps is it also a circuit breaker,CNC rep call? If so 430 22a calls for 140% (58kva / 398 =145.72x1.4=204, 200 amp fuse) will this calculation not protect the CNC if the breaker is a 150 amp disconnecting on off switch mounted on equipment. OR should further intermittent duty ,at 90 %or 85 % from 430-22a , more of a operators job task ,which every one is different. For a $100,000.00 machine , would like to be more accurate. Needing some reassurance ;200 amp 3-phase disconnect ,200 amp time delay fuses ,feeders =150 x125%=187,2-0 awg cu. CNC CO. response :Engr?ing Tech Spec (757-4002-630) calls out 58 KVA as Service Req for VMX24HS. Sure 58KVA is full load with options. Since we do not know application and this machine model?s servo axes and spindle regenerate back to line Hurco will not indicate a lesser value. Electrican of course can derate if they so choose. Appreciate any help ,God Bless
 
My experience with Hurco and most other CNC machines is they already have service disconnect and all other motor protection in the cabinet... All you should have to do is protect your wires (breaker) and provide a service disconnect should the machine need to be removed. (breaker in the panel marked as Service Disconnect may qualify if within sight etc.)

Note: make sure the protection has been changed to correct voltage and frequency.
Most of the foreign equipment I've worked on this would require re-tapping all transformers, motors, etc, changing out overload coils, some motor controllers, relay coils etc.

You might want to have a factory tech to come in and do this for you or at least check it for you... then when something does blow up it would be manufacturer's responsibility to replace the invariably expensive components.:thumbsup:
 
CNC mystery

CNC mystery

Thanks for the input . the owner saying the CNC has a 47 hp motor( have no Idea , maybe a salesman, and the name plate calling for a largest mtr 25kva @ 36 amps. So all the start up and motor feeds are already done and the 150 disconnect is the total for wire size and circuit breaker. 1-0 awg and 150 amp disconnect, thats a deal. Am I just over thinking it and breaking my peace. Thanks
 

pfalcon

Senior Member
Location
Indiana
First off, please draw a breath when typing. That is, please break up long posts by using line breaks (enter key) between topic changes. Makes it far easier to read and find your questions.
I hope this is not to confusing my dilemma is the fuse vs circuit breaker for CNC lathe disconnecting means and straight up 150amps due to manufactures calculations ( choice of circuit breaker per owners budget, I told him time delay fuses open in less cycles).
The best choice for equipment protection is a type 2 fuse. Bussmann has a lot of instructional documents you can read.
I'm delivering the power to the lathe, I could not get any specs on this for its new and nothing on the manual about line (power source and disconnect) the tech person said its 145 amp ,and 58 kva > full load amps =150 amp and to use fused disconnect. IF I go by the manufactures name plate as full load amps of 150 amps ,60kva / 398 =150.75 is there should not be any further calculations for the fuses for supply?, or is 150 amp gospel by manufactures nameplate and my responsibility is to deliver 150 amp supply , I hear what your saying about it'll never see this amperage due to intermittent starts and other equipment .
A 150A fuse doesn't instantly trip at 151A. Which is a good thing. Most of our machine tools have transformers immediately after the disconnect. The inrush on a transformer is 35 to 85 times the FLA of the transformer (depending on who you ask and who the OEM is). So a 150A transformer pulls 5000A to 12750A during inrush. That's why there are special fuses for transformers. Typically dual-element.
Short answer: If the machine tool maker says use a 150A fuse then use a 150A fuse at the disconnect.
Selective coordination is tough to perform with circuit breakers. To properly install selective coordination both devices must have been tested together. So rarely can you ever cross brands. Most selective coordination is done with fuses. Jim gave a good fuse selection. But I would point out that the best ratio offered by Bussmann is 2:1 if you pick the right fuses. Other combinations require ratios much higher such as 8:1.
In this shop of 50 or so CNC lathes I have yet to see one fuse-able disconnect to any individual motor( per last electrical co. with Challenger panels and breakers). The 150 amps that I propose to install will tapp off a gutter that feeds 2 panels, the main power source is a 200 amp fuse able disconnect tapped from gutter then fed from meter,selective coordination over current device (200 amp 3 phase fused disconnect should have current limiting fuses,therefore the gutter down line would be ok with a circuit breaker disconnect for the 150 amp lathe.
The disconnect for the motors on a machine tool is typically the disconnect on the main electrical enclosure.
I have eliminated one three phase panel to accommodate the 150 amps due to machines not being used. My question is the current limiting and quick action of the fuses more favorable at the power source and down line, or is it not necessary due to selective coordination(main 200 amp 3phase disconnect with fuses).. the gutter that will feed the 150 amps already has a 200 amp fuse-able disconnect feeding these panels so circuit breaker is acceptable? Thanks fore the sound board and any advice on the supply power source and disconnecting means. If its confusing I'm tired and will check before bed or morn if anyone can give some solid advice
Presume that the machine will draw current equal to the FLA when sizing things. Put the 150A fuse in the machine disconnect as the manufacturer specified. The majority of our machines only use normal coordination - not selective.
 

pfalcon

Senior Member
Location
Indiana
Thanks for the input . the owner saying the CNC has a 47 hp motor( have no Idea , maybe a salesman, and the name plate calling for a largest mtr 25kva @ 36 amps. So all the start up and motor feeds are already done and the 150 disconnect is the total for wire size and circuit breaker. 1-0 awg and 150 amp disconnect, thats a deal. Am I just over thinking it and breaking my peace. Thanks

First follow the advice from DaveTap. ALWAYS (even when domestic) read the machine nameplate to make sure you're providing the named voltage, phase, amps, frequency. If you provide according to the nameplate then Hurco gets to foot the replacement if they wired wrong.

You should only have to check motors if the machine doesn't have it's own transformer after the disconnect. But you might have to make sure they provided the correct transformer (or tapped it right).

And as DaveTap suggested, though I would wire it, I would also keep it locked out until after a Hurco rep came in and inspected.
 
CNC second Tech Rely

CNC second Tech Rely

Thanks for the input, I can take a deep breath now for your sage help and advice( I apologize for the typing, I was anxious ). Another factory rep told me late Friday , basically what Dave Tapp was saying, " that the main on the electrical cabinet was all the calculated loads and I would Have to supply." To protect the wire feeder with a circuit breaker of 150 amps.

Is the fuses the best bet due to current limiting without equipment damage? Even though the second rep and owner insist on circuit breaker?
would Liability release be in order,just throwing it out there? If it fails you know who gets to own it no matter what.

The 400 amps 3 phase I believe is 230x1.732=398.36 rounded up to 400.

The last tech I talked to said " 47 hp mtr is intermittent duty of one minute and sounds like the owner and the start up tech don't realize this and made a assumption of this mtr operating @ continuous duty.



The tech also said; If the voltage is 240 3 phase, instead of 230 3 phase that it would need to be cleaned up. what ( buck -boost transformer) and where would one find more info on the specs and hook up requirements. THANKS & GOD BLESS U & AMERICA!
 
CNC DROP

CNC DROP

The tech says the penetration is on top. I saw a plastic two piece grommet.

Will the cord from top be more practical and safe in a open cabinet for operator or some type of nonmetallic sleeve over wire in cabinet?

my disconnect is on the wall not from top buss bar or other.

I have never seen a 1-0, 4 cord and what usage Type sct or other ( no traffic ?

I was thinking 1 1/2 seal tight flex mounted on strut and penetrating side of cabinet but don't think that's what their looking for.

I'm thinking this cord will be expensive and back ordered any suggestions or related experience?
 
CNC transformer

CNC transformer

WEll (its deep) the voltage is A-240, B-240, C-245(high leg),
The tech says he wants 230 volt 3 phase and no more or less, I'am about to walk away from this but still need to make that decision. I went to school for this in 85 and have never used that knowledge and am not confident enough on a 100,000 dollar machine.
I am still searching for the answer have looked on previous threads.
Its obvious that I need expertise in the motor industry , any suggestions will be appreciated. Thanks
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems
Machine techs will always blame the electrical supply.
They always say they never have these issues in any other facility.

You are over thinking this installation.

Once you figured out your branch circuit ampacity, you simply choose a standard protective device. Anything specific for the machine is contained inside of the machine or else it is clearly spelled out in the instructions. (By the way, current limiting does not mean there is no damage, so this is not a controlling concern).

The nominal voltage in the US, including you facility. is 240V. If you need to supply 230V then you need a simple buck-boost transformer.
There is no service that will deliver an exact voltage, remember the utility is allowed +/- 5% variance at any time.
Except for specialized machining, like in the semiconductor field, I have never seen a 'constant voltage' source used for a CNC.

If guarantees are required, then walk away.
 

pfalcon

Senior Member
Location
Indiana
... Is the fuses the best bet due to current limiting without equipment damage? Even though the second rep and owner insist on circuit breaker? ...
The machine tool disconnect should already be a circuit breaker or a fuse. Don't change it. If it's a fuse set then install the size and type recommended by the machine tool builder. The upstream OCPD can be whatever you want. The liability shifts to you only if you change the machine.
 

pfalcon

Senior Member
Location
Indiana
WEll (its deep) the voltage is A-240, B-240, C-245(high leg),
The tech says he wants 230 volt 3 phase and no more or less, I'am about to walk away from this ...

Machine techs will always blame the electrical supply. ...The nominal voltage in the US, including you facility. is 240V. If you need to supply 230V then you need a simple buck-boost transformer.
There is no service that will deliver an exact voltage, remember the utility is allowed +/- 5% variance at any time. ... If guarantees are required, then walk away.

For comparison, my plant has 480Vac 3phase +/- 10%.
 

pfalcon

Senior Member
Location
Indiana
The tech says the penetration is on top. I saw a plastic two piece grommet.

Will the cord from top be more practical and safe in a open cabinet for operator or some type of nonmetallic sleeve over wire in cabinet?

my disconnect is on the wall not from top buss bar or other.

I have never seen a 1-0, 4 cord and what usage Type sct or other ( no traffic ?

I was thinking 1 1/2 seal tight flex mounted on strut and penetrating side of cabinet but don't think that's what their looking for.

I'm thinking this cord will be expensive and back ordered any suggestions or related experience?

Top penetration means leaks into the enclosure. Things vibrate and shift around here.
Cord isn't typically used on a machine tool. Conduit is more common.
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems
For comparison, my plant has 480Vac 3phase +/- 10%.
I find it odd that your utility is allowed a 20% voltage swing.
Your utilization equipment may have that rating, but utilities are normally closer to a 10% range (+/-5%).
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
PE (Retired) - Power Systems
What can I say? I got that from the plant facilities electrical engineer for what he's providing to my machine tools.
I often get two choices where I work - :rotflmao: or :cry:

Utilities are usually limited to +/-5% with another 5% swing from internal facility operations. The end result is a theoretical +/-10% voltage range at the actual utilization equipment.
 
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