Miyano 34T CNC Lathe

[eager2learn]

230v 3 phase
Main motor horsepower 7.5
Total Horsepower 17.5

I need to know how to size the conductors accordingly

Please advise

I'm confused. Do I use the main motor horsepower or the total horsepower?

Thank you in advance

Need asap

 

[chris kennedy]

Total KW not on nameplate?

 

[petersonra]

Total KW not on nameplate?

the code requires a nameplate on the machine. the information from (1), (2) and (3) in the nameplate will allow you to size the feeder conductors and choose the rating of the OCPD.

670.3 Machine Nameplate Data.
(A) Permanent Nameplate. A permanent nameplate shall
be attached to the control equipment enclosure or machine
and shall be plainly visible after installation. The nameplate
shall include the following information:
(1) Supply voltage, number of phases, frequency, and fullload
current
(2) Maximum ampere rating of the short-circuit and groundfault
protective device
(3) Ampere rating of largest motor, from the motor nameplate,
or load
(4) Short-circuit current rating of the machine industrial
control panel based on one of the following:
a. Short-circuit current rating of a listed and labeled
machine control enclosure or assembly
b. Short-circuit current rating established utilizing an
approved method

Most times the manufacturer of the machine supplies this nameplate.

 

[eager2learn]

No there is no kw on the nameplate

 

[eager2learn]

If I size the conductors off of the 7-1/2 horsepower rated at 230v I get 22 motor amperes with a 45 amp sized breaker #10 thhn 3/4 " emt

 

[eager2learn]

If I use the 17-1/2 horsepower or total horsepower than I will have 54 motor amperes with a 100 amp breaker with #4 thhn in 1" conduit

 

[eager2learn]

I just need to know what calculation to use. The previous owner was running the equipment off of a 200 amp main breaker that ran directly into the cabinet. I want to make sure that I am doing the install correctly. Any information will be greatly appreciated

 

[Fulthrotl]

If I use the 17-1/2 horsepower or total horsepower than I will have 54 motor amperes with a 100 amp breaker with #4 thhn in 1" conduit

that is where i'd put it.

all the breaker is protecting is the wire.
the equipment has it's own protection.

the last thing you want to have happen is
to have that breaker open 'cause you undersized
it, in the middle of a heavy fly cut.

 

[eager2learn]

Okay so your saying I should witevit up for the 17-1/2 horsepower just to be in the safe side but my customers don't want to pay for the additional cost in material. Thank you

 

[JFletcher]

Okay so your saying I should witevit up for the 17-1/2 horsepower just to be in the safe side but my customers don't want to pay for the additional cost in material. Thank you

extra cost for what? if you need #4 and 1" conduit, that's what you need. Its not like you're gonna be able to run 14/3 NM to it... labor is probably much more than materials anyway isnt it?

Does the customer even have 240V 3 ph, or is he working with 208?

eta: if you are at 54A you could use #6 in a 3/4" conduit. Its unlikely that lathe will ever see a max load and would never be started under a load.

Dont forget to factor voltage drop if it's a long distance from lathe to panel.

 

[JFletcher]

I tried looking up a manual for that machine, every site wanted me to register for a pdf... not happening. I would presume the electrical specifications are in the manual... if not, a friendly call to someone with one of these machines may get you further than guessing at what to wire it with. Personally, I would not go with 3/4" conduit, because if #6 is too small for some reason, you cant pull 3/4 #4 in 3/4...

After looking up that model, it's more than a standard lathe... has cooling pumps that will run constant, main spindle motor, and I presume at least one other motor for xyz milling/drilling.

 

[eager2learn]

Thank you all very much for your input. I decided to install #6 with 3/4. Thanks again

 

[petersonra]

Thank you all very much for your input. I decided to install #6 with 3/4. Thanks again

for a 240V 3 phase system

17.5 total HP = 48 Amps (extrapolated somewhat from the tables)

25% of 7.5 Hp = 5.5 Amps

total 53.5 Amps

it would appear if those are your only loads the wire ampacity meets code.

 

[JFletcher]

Thank you all very much for your input. I decided to install #6 with 3/4. Thanks again

You're welcome. Good luck. What breaker size? Is 100A right for a 54A draw? The main motor is 7.5 HP, total 17.5 HP. If someone would be so kind as to direct me to a code section dealing with sizing OCPD when there are multiple motors involved, I thank you in advance.

 

[Fulthrotl]

Thank you all very much for your input. I decided to install #6 with 3/4. Thanks again

in the late 1980's ~ early 1990's i did nothing but machine shop hook ups
for a machine tool broker.

based on that.... i'd pull #2's in a 1" conduit, and fuse it at 100 amps.
i'd also put a T condulet at the 90 above the motor drop, and pull straight
thru it.

machine shop owners are worse than pigeons when it comes to putting crap
everyplace. in six months, you'll end up putting a 10 amp 3 phase load
piggybacked off that 100 amp circuit to feed a disconnect powering up
a little surface grinder he bought at auction.

i've done a lot of machine shops.

also, i've learned in the aerospace job shops around LA, get your material
costs up front.... everything i learned about chasing money owed to me
was taught by a machine shop owner for the first lesson.

they are really good teachers.

 

[Jraef]

Since it IS a machine tool, if more than one of the motors have a have a VFD on them, there are some here who will argue that it changes the conductor sizing equation.

<Tosses grenade into the room and runs for cover... hmy:>

 

[JFletcher]

Since it IS a machine tool, if more than one of the motors have a have a VFD on them, there are some here who will argue that it changes the conductor sizing equation.

<Tosses grenade into the room and runs for cover... hmy:>

*picks up grenade*

Please elaborate. I didnt check or notice if the OP's machine had VFDs, but if it did, how would that affect conductor sizing? Would he need multiple circuits vs one?

and yes, I deal with VFDs about 0.001% of the time - looking to learn about them some here, before the grenade blows...

 

[Ingenieur]

Since it IS a machine tool, if more than one of the motors have a have a VFD on them, there are some here who will argue that it changes the conductor sizing equation.

<Tosses grenade into the room and runs for cover... hmy:>

hmy:
lol

I can't imagine that the machine does not have a nameplate, a manual or that the mfg will not provide support