Understanding foreign nameplate rating

[delectric123]

Its been awhile since I had to calculate circuit requirements so I'm a bit rusty. Trying to determine correct circuit ampacity requirements without overkill. The specs are confusing as they use different terminology and voltage. This is a CNC lathe with multiple motors. The 35 kva does not match the 220 volts x 101 amps(38,485 va)
101 x 1.25 amps requires 1 awg copper , but that 101 amps technically makes a 125 amp breaker insufficient. but doing 38,485 va with 230v brings 96.6 amps which makes me good to go
Or should I just use the 35 kva?
Can someone direct me the correct path for calculating this? thanks.

 

[Ingenieur]

you can use the 125 cb (can be smaller than
the conductor, but not larger, except for motors)
imo since #1 is 130 you could use the next size up (150?)

so the conductor is good for the 101 A or 35 kva
and the 125 will protect the conductor

 

[delectric123]

Thinking this over a bit more. Do I actually need to factor in 125%?
On Equipment with NEC labeling it would state minimum circuit ampacity with 125% already factored in.
Not sure how IEC or such does that.
That would bring me down to 3 AWG and 100 amp circuit = less $$. Quite honestly that looks like a more reasonable size.
The machine isn't purchased yet, so I can't look it over to see what the load actually consists of, but do know the main motor is 20 HP = 54 amps. + a few small ones.
Thanks

 

[jumper]

Thinking this over a bit more. Do I actually need to factor in 125%?ecec
On Equipment with NEC labeling it would state minimum circuit ampacity with 125% already factored in.
Not sure how IEC or such does that.
That would bring me down to 3 AWG and 100 amp circuit = less $$. Quite honestly that looks like a more reasonable size.
The machine isn't purchased yet, so I can't look it over to see what the load actually consists of, but do know the main motor is 20 HP = 54 amps. + a few small ones.
Thanks

No, it does not say MCA so you cannot assume it is factored in.

Usually MCA is a HVAC spec.I doubt that is the case here.

FLC does not mean MCA.

 

[Besoeker]

Its been awhile since I had to calculate circuit requirements so I'm a bit rusty. Trying to determine correct circuit ampacity requirements without overkill. The specs are confusing as they use different terminology and voltage. This is a CNC lathe with multiple motors. The 35 kva does not match the 220 volts x 101 amps(38,485 va)
101 x 1.25 amps requires 1 awg copper , but that 101 amps technically makes a 125 amp breaker insufficient. but doing 38,485 va with 230v brings 96.6 amps which makes me good to go
Or should I just use the 35 kva?
Can someone direct me the correct path for calculating this? thanks.

View attachment 19750

The nameplate has an error in expressing rated power as kVA. Power ought to be given in kW and could be 35kW with a lower than unity power factor resulting in the 38kVA.
It's one explanation for the apparent disparity.

 

[Ingenieur]

The nameplate has an error in expressing rated power as kVA. Power ought to be given in kW and could be 35kW with a lower than unity power factor resulting in the 38kVA.
It's one explanation for the apparent disparity.

that would make sense
35 kw / (sqrt3 101 220) ~ 0.91

 

[ActionDave]

Thinking this over a bit more. Do I actually need to factor in 125%?
On Equipment with NEC labeling it would state minimum circuit ampacity with 125% already factored in.
Not sure how IEC or such does that.
That would bring me down to 3 AWG and 100 amp circuit = less $$.

I would skip the 125% and run a hundred amp circuit.

 

[delectric123]

Thanks for all the replies, looks like no oppositions with 100 amp circuit. When we have the machine I'll go over all the motors to see for sure. But for now I just want to have a plan in place. From what I've seen on other lathes the other motors' FLA amount to nothing significant. Though it would be interesting to know how the foreign machinery nameplate terminology should be applied.

 

[kwired]

Thanks for all the replies, looks like no oppositions with 100 amp circuit. When we have the machine I'll go over all the motors to see for sure. But for now I just want to have a plan in place. From what I've seen on other lathes the other motors' FLA amount to nothing significant. Though it would be interesting to know how the foreign machinery nameplate terminology should be applied.

Unless it gets put to really hard usage, it probably never draws 101 amps. Lathe type machine would have to be making wide or deep cuts (or both) into harder cutting type materials to load it that hard. Most typical uses probably are lesser loading conditions, then speed the spindle is operating at factors into the loading conditions also.

Rough cutting is likely going to be higher load demand as the desire is usually to remove unwanted material quickly, finishing cuts and polishing actions are going to be lighter load demands as material is removed at slower rates, higher spindle speed possibly but not nearly as deep of a cut.

 

[petersonra]

I run across this kind of thing now and then. I would probably put a 150A MCCB on it and have the electrician run 1/0 copper. It is more cost effective than worrying about it and having to explain it to a bunch of people, and then having meetings about it. No one will argue that a 150A MCCB with 1/0 copper is not acceptable. The $50 or $100 you might save by using a smaller conductor is not worth the aggravation of having to explain it later.

JMNSHO

 

[Mgraw]

I run across this kind of thing now and then. I would probably put a 150A MCCB on it and have the electrician run 1/0 copper. It is more cost effective than worrying about it and having to explain it to a bunch of people, and then having meetings about it. No one will argue that a 150A MCCB with 1/0 copper is not acceptable. The $50 or $100 you might save by using a smaller conductor is not worth the aggravation of having to explain it later.

JMNSHO

I agree. It is cheaper to do it right the first time than to redo it on your own dime. I can see this machine tripping on startup with a 100 amp breaker.

 

[Ingenieur]

I run across this kind of thing now and then. I would probably put a 150A MCCB on it and have the electrician run 1/0 copper. It is more cost effective than worrying about it and having to explain it to a bunch of people, and then having meetings about it. No one will argue that a 150A MCCB with 1/0 copper is not acceptable. The $50 or $100 you might save by using a smaller conductor is not worth the aggravation of having to explain it later.

JMNSHO

agree
#1 not 1/0 though?

 

[petersonra]

agree
#1 not 1/0 though?

JMNSHO. The motor nameplate is not NEC compliant since it does not show a HP rating. Just how would you select the ampacity required from the charts since there is no HP listed on the nameplate? I would just as soon run a general purpose 150A branch circuit that no one can argue with and be done with it.

 

[GoldDigger]

JMNSHO. The motor nameplate is not NEC compliant since it does not show a HP rating. Just how would you select the ampacity required from the charts since there is no HP listed on the nameplate? I would just as soon run a general purpose 150A branch circuit that no one can argue with and be done with it.

FWIW, European motors may use kW instead of HP on the nameplate to refer to mechanical output rather than electrical input. If that is the case here a straight numerical factor conversion from kW to HP would be interesting to look at to get an idea of what would be the HP rating on a US standard nameplate.
In this particular case, the fact that the nameplate shows kVA rather than kW complicates things further.

 

[Ingenieur]

I'd size it on the larger of the 2, 35 kva or 101 A
35 kva = 92 A (35000/(sqrt3 220) )
so 101 x 1.25 = 126, #1 75 C 130 A

I don't consider it a single motor
imo a machine or control panel

 

[jumper]

I'd size it on the larger of the 2, 35 kva or 101 A
35 kva = 92 A (35000/(sqrt3 220) )
so 101 x 1.25 = 126, #1 75 C 130 A

I don't consider it a single motor
imo a machine or control panel

If a train driver speced a #1, I would run it but left to my own decision I would do the 1/0.

Since there might be a variable or two that I am not aware given the machine is different then what I was used to, I would hate to be caught short after I used the smaller size.

This is from an installer’s point or view.

 

[Mgraw]

I'd size it on the larger of the 2, 35 kva or 101 A
35 kva = 92 A (35000/(sqrt3 220) )
so 101 x 1.25 = 126, #1 75 C 130 A

I don't consider it a single motor
imo a machine or control panel

It probably has 6-7 motors in it.

 

[jumper]

I am more worried that given just given the nameplate and being around the ~100A level and #1 or 1/0 level that 110.14(C) could come to play.

I would run the numbers like Iggy did, but not exactly knowing if I had 60C or 75C terminals, I like a bit of CYA. Foreign made equipment.

 

[Ingenieur]

If a train driver speced a #1, I would run it but left to my own decision I would do the 1/0.

Since there might be a variable or two that I am not aware given the machine is different then what I was used to, I would hate to be caught short after I used the smaller size.

This is from an installer’s point or view.

either way is a better option than a 100 A ckt

me #1 and 150 cb (if the motors are vfd possibly 125 cb)

another variable is length, v drop may be an issue at 220
though in this case supply is likely 240

 

[jumper]

either way is a better option than a 100 A ckt

me #1 and 150 cb (if the motors are vfd possibly 125 cb)

another variable is length, v drop may be an issue at 220
though in this case supply is likely 240

The 100A ckt. was someone else’s idea, I would never have done that unless ordered to in writing.