1/2 HP FLA is Strangely High

B

bwat

EE
Location
NC
Occupation
EE
Designing a panel that will control some motors and customer told me the FLA for the 1/2hp blower motor is 2A (@480V/3ph). This sounded at least 2x too high, so asked for a picture of the nameplate. Attached.

I agree that this is what it looks like it shows (0.5HP and 2A for 460V). Isn't this current wildly high for 1/2hp?

I can't get to that same current even after considering the efficiency and awful PF listed. I don't think I've seen a nameplate FLA so much higher than NEC FLC table.

(There's something like 12 of them that we are controlling and supplying, so any error is off by 12x).
 

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I agree with your assessment, but your choices are to use the nameplate data or go back to Baldor with your query.

Even with 12 motors, the impact on your panel design should be pretty minimal - a larger main breaker, perhaps?
 
Have you put an ammeter on phase leggs to see actual running draw?

Which brings another question. Will amperes be total current between phase a,b and bc and ac ?
 
retirede said:
I agree with your assessment, but your choices are to use the nameplate data or go back to Baldor with your query.

Even with 12 motors, the impact on your panel design should be pretty minimal - a larger main breaker, perhaps?
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Yeah it ends up influencing a main conductor and breaker size when totaling up everything else (250A vs 300A) that have some lead time differences between the two. I think we have to just roll with it
 
Googled a few motor charts. One stated that a 1/2 HP three phase 1800 RPM motor on 460 volts draws 0.86 amps. Second chart stated 1 amp, third stated 1.1 Amps Fourth stated 1 amp. Is there any way of running one of these 1/2 HP fully loaded and take ampere reading on all three legs ? Baldor always was best in class motor manufacturer. Years ago we had maybe a dozen 5 HP chocolate pumps on old equipment that had 1950 era U frame motors. When they replaced them with modern motors the shafts did not extend as far out so they installed three groove pulleys and only used the outer two extended a little past end of shaft. First three brands they tried broke motor shafts within a month or two. Then tried Baldor and the shafts never broke. I never liked the obsolete motor ampere chart in the NEC. They appear to be 10 to 20% higher then the 99% of plain Jane NEMA 2 & 4 pole General use motors that I came across. You might want to contact both Baldor & your AHJ on any current adjustments that could be changed. I strongly disagree with NEC motor ampere charts whenever a VFD without a bypass is used. We always set the ramp.up time for at least ten seconds and a lot longer on pumps & fans that ran 24/7. I ran several 100 HP 480 volt motors with a 124 FLA from a drive that was only feed by 150 amp quality time delay fuses. Some on AHU fans and others on pumps.
 
retirede said:
The Eff and PF are on the nameplate. Using those values doesn’t reconcile. That’s his question.
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I see your point. Wouldn't be the first time I've seen odd Baldor plate data. I come up with 1.16A at 460V, but he will be running 480.

If it goes all the way up the commercial flag pole, it's probably a good idea to both contact Baldor, and either get an explanation or get their error in writing. They may have added other factoring such as voltage sag.
 
I did a google search for the specification number on the dataplate. I didn't find any exact matches but I did find a bunch (from Baldor) that were the same voltage, speed, and horsepower, but with half the current.

IMHO this is worth a call to Baldor to confirm the numbers.
 
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