# Cletis Question......Starter Voltage vs. HP



## micromind (Aug 11, 2007)

Since they won't let Cletis back on here and it's sorta slow around here, I thought a good ol' fashion Cletis question might liven it up a bit......

A size 3 NEMA starter is rated at 25 HP @ 200 volts and 30 HP @ 230 volts. It's also rated at 90 continuous amps. 

Do the HP ratings apply to the system voltage or the motor nameplate voltage?


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## macmikeman (Jan 23, 2007)

micromind said:


> Since they won't let Cletis back on here and it's sorta slow around here, I thought a good ol' fashion Cletis question might liven it up a bit......
> 
> A size 3 NEMA starter is rated at 25 HP @ 200 volts and 30 HP @ 230 volts. It's also rated at 90 continuous amps.
> 
> Do the HP ratings apply to the system voltage or the motor nameplate voltage?


We had to look at that stuff on the daily code tip from Mike Holt all last week for crying out loud............:thumbsup:


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## NC Plc (Mar 24, 2014)

Motors are rated with peak HP I think.


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## triden (Jun 13, 2012)

Hence why IEC starters are selected based on FLA. No confusion :whistling2:


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## JRaef (Mar 23, 2009)

micromind said:


> Since they won't let Cletis back on here and it's sorta slow around here, I thought a good ol' fashion Cletis question might liven it up a bit......
> 
> A size 3 NEMA starter is rated at 25 HP @ 200 volts and 30 HP @ 230 volts. It's also rated at 90 continuous amps.
> 
> Do the HP ratings apply to the system voltage or the motor nameplate voltage?


Motor nameplate voltage. A motor designed for use ONLY on a 208V system will be a 200V winding design, 230V windings are for a 240V distribution system, 460V for a 480V system, etc.

The blurry line is in smaller motors with "208/230V" on the nameplate. That's really a compromise and the windings are really 230V, but with a little more iron to handle the extra heat if run at 208V. You can think of those as being 230V +10, -15% tolerance instead of +-10%. But you won't find that nameplate on a 25HP motor, the mfrs stop at 10HP with those nameplates. So a NEMA Size 3 starter will show the different HP ratings


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## emtnut (Mar 1, 2015)

JRaef said:


> Motor nameplate voltage. A motor designed for use ONLY on a 208V system will be a 200V winding design, 230V windings are for a 240V distribution system, 460V for a 480V system, etc.
> 
> The blurry line is in smaller motors with "208/230V" on the nameplate. That's really a compromise and the windings are really 230V, but with a little more iron to handle the extra heat if run at 208V. You can think of those as being 230V +10, -15% tolerance instead of +-10%. But you won't find that nameplate on a 25HP motor, the mfrs stop at 10HP with those nameplates. So a NEMA Size 3 starter will show the different HP ratings


I thought the bigger motors also had dual ratings, for reduced voltage starting... but the HP remained constant which is what you base your starter on.


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## AK_sparky (Aug 13, 2013)

triden said:


> Hence why IEC starters are selected based on FLA. No confusion :whistling2:


Ya, IECs are way better than NEMAs! Can I get a "hell ya!" from everyone!


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## emtnut (Mar 1, 2015)

micromind said:


> Since they won't let Cletis back on here and it's sorta slow around here, I thought a good ol' fashion Cletis question might liven it up a bit......


Who is this Cletis you speak of, and why thee have forever banished,as was done with Moses ? :blink:


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## JRaef (Mar 23, 2009)

emtnut said:


> I thought the bigger motors also had dual ratings, for reduced voltage starting... but the HP remained constant which is what you base your starter on.


230/460 or 9/12 lead for reduced voltage starting, yes. But you would not see 208/230V as a low voltage rating above 10HP.


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## B-Nabs (Jun 4, 2014)

emtnut said:


> Who is this Cletis you speak of, and why thee have forever banished,as was done with Moses ? :blink:


Do a thread starter search for Cletis. He was a member here who used to post ridiculous questions, and usually his threads would go on and on with people debating the minutiae of what was, to begin with, a silly troll question. Basically he is the quintessential ET troll. People will still occasionally refer to a ridiculous thread as "cletis". Personally, I miss him.

Sent from my SM-G920W8 using Tapatalk


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## Meadow (Jan 14, 2011)

AK_sparky said:


> Ya, IECs are way better than NEMAs! Can I get a "hell ya!" from everyone!



I think we need NEMA equipment with IEC rules for application. Best of both worlds.


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## micromind (Aug 11, 2007)

I figured it was actual nameplate voltage and not supply voltage as well. 

I don't know for sure, but I'd bet that at least some motors marked 208-230/460 are actually designed for 220/440. Same goes for 115/208-230, actually 110/220. 

So lets say we had a Baldor #EM2535T, 30HP, 230/460, 70/35 amps. The nameplate also states 'usable at 208 volts and 74.1 amps'.

It seems that if this motor were supplied by 208, it'd need a size 4 starter. Or would it? 

Both magnetizing and locked-rotor current would be less on 208 than 230, so it would be less of a strain on the starter, and the full-load current is less than the maximum continuous current of a size 3, so requiring a size 4 makes no sense. 

Or does the maximum of 25HP for a size 3 apply only to motors marked 200 volts?

Baldor also makes a 200 volt version of this motor, its FLA is 81. But its locked rotor current is 514 amps vs. the 230 volt model 447 amps. Presumably, the magnetizing current would be higher as well. 

I can easily see needing a size 4 for this motor, but not for a 230/460 one that's also rated for and operated at 208. 

I don't know about anyone else, but I really enjoy ultra-technical sometimes useless stuff like this. Lol.


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## micromind (Aug 11, 2007)

While IEC stuff certainly has its place, a lot of my motor experience has been mines, rock crushing plants, asphalt plants, concrete plants and other 'high abuse' environments. 

My experience is that IEC starters don't hold up very well but NEMA does.


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## JRaef (Mar 23, 2009)

micromind said:


> ...
> Or does the maximum of 25HP for a size 3 apply only to motors marked 200 volts?...


"Officially", a NEMA Size 3 is good for 30HP at 230V, then _25HP at 200V_. But that's because "officially", the NEC says that a 200V 30HP motor will have a FLC of 92A, and a NEMA Size 3 starter is rated for 90A continuous. So "officially", they can't say that a 30HP 200V rated motor can be started by a Size 3 starter, because "they" have no idea what the ACTUAL FLC of that motor is, the starter mfr must go by the NEC charts. 

Also remember, NEMA is not actually a regulatory body, it is a collection of mfrs who publish a guideline for selecting equipment. Officially, UL tests them according to the maximum continuous current based on an inductive load (assuming that a resistive load is less strenuous, therefore no need to worry about it). So if you look carefully in NEMA motor starter charts, the wording is something like "Full Load Current must not exceed Continuous Ampere Rating". THAT is what actually matters.

If the motor FLC at 208V is listed as only 74.1A, I would not hesitate to use the Size 3 starter.


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## JRaef (Mar 23, 2009)

micromind said:


> While IEC stuff certainly has its place, a lot of my motor experience has been mines, rock crushing plants, asphalt plants, concrete plants and other 'high abuse' environments.
> 
> My experience is that IEC starters don't hold up very well but NEMA does.


I've done a lot of crushing plants too. We used to say that IEC stood for "*I*mpending *E*lectrical *C*atastrophe". I've seen some spectacular failures of IEC components in crushing plants. As my partner always loved pointing out;

_Fred Flinstone and Barney Rubble worked at a rock quarry. They still do..." _meaning that the operators in that industry are still Neanderthals.

IEC for pumps, fans and little conveyors moving boxes of cotton balls, no problem, in fact NEMA is over kill for most of those applications.


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## Tony S (Jan 27, 2014)

JRaef said:


> _Fred Flinstone and Barney Rubble worked at a rock quarry. They still do..." _meaning that the operators in that industry are still Neanderthals.


If that’s your attitude, I’m going to sulk!

I’ve got to agree, a quarry operative can wreck anything without even trying. After 24 years of mayhem I went in to the steel industry, out of the frying pan in to the fire.

We always looked for contactors to BS-EN60947-4-1 (similar specifications to NEMA) in the hope they would survive. Some of the batch feeders would start 60/70 times per hour, given the number of feeders failures were surprisingly rare.

These were the preferred type.
http://www.hubbell.co.uk/pdf/Contactors.pdf


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