Understanding foreign nameplate rating

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kwired

kwired

Electron manager
Location
NE Nebraska
petersonra said:
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
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All we got from OP was picture of nameplate and very limited information, I'd at looking at what this machine truly is and taking that information into consideration before just assuming a 100 amp circuit will be fine. But from the information we do have seems there is a good chance 100 amp circuit would seldom if ever be overloaded.
 
D

delectric123

Senior Member
Location
South Dakota
Thanks for all the replies. I don't have more information on the machine to offer right now. The 20 HP motor is VFD, 100 amp would likely work load wise, but to be on the safe side of legality I'll probably do #1 and 125A CB.
 
kwired

kwired

Electron manager
Location
NE Nebraska
delectric123 said:
Thanks for all the replies. I don't have more information on the machine to offer right now. The 20 HP motor is VFD, 100 amp would likely work load wise, but to be on the safe side of legality I'll probably do #1 and 125A CB.
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Is a 20 HP motor plus controls all there is for loads? If so and even if on VFD driven a 60 or 70 amp breaker probably never trips because of the soft start nature of VFD driven applications.

20 HP @ 208 or 240 volts only requires #4 copper before any adjustments come into play, if that nameplate is 101 amps there must be other loads though.
 
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delectric123

Senior Member
Location
South Dakota
kwired said:
Is a 20 HP motor plus controls all there is for loads? If so and even if on VFD driven a 60 or 70 amp breaker probably never trips because of the soft start nature of VFD driven applications.

20 HP @ 208 or 240 volts only requires #4 copper before any adjustments come into play, if that nameplate is 101 amps there must be other loads though.
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20 Hp plus small motors, don't have info on the small motors yet.
 
Jraef

Jraef

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Location
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Electrical Engineer
A typical Moro Seki CNC center will have upward of 7 motors (mentioned earlier) depending on its vintage, function etc. The spindle will be the biggest, then it will have a separate smaller tool spindle, lube pump, at least 2, maybe 3 Servo/Stepper axis drives, possibly a tool changer (Servo or stepper), screw cutter drive etc etc.

https://youtu.be/ar79zQMWnGM

Every motion you see in this video is a separate motor, most of them Servo drives, so like VFDs, they are powered via electronics. Inrush current and power factor isn’t an issue, hence the total load being expressed as kVA.
 
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teco

Senior Member
Location
Mass north shore
Mgraw said:
In post 26 OP stated 20 hp motor plus other motors. The 101 amps is fla not mca.
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Same answer.
35 KVA = 91.96 3-phase amperes.
20 hp spindle motor = 54 x 1.25 = 67.5 largest motor.
91.96 + 13.5 = 105.46
Still #2 copper, still 125 amp breaker.
This is based on 35 KVA not fla.
Though the fla in this instance must be the total current as it’s listed under tool not any particular motor.
Btw, the spindle motor hp listed in the specifications of this machine model number is 15 hp continuous rated.
 
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