New IE4 Motor - Pulling more Amps but less kW

[Richo106]

Hi All

Apologies for a random but maybe a very simple question, last week we replaced an IE2 200kW motor for an IE4 200kW motor

The FLC on the existing IE2 was 318A and the FLC on the new IE4 motor is 347A at 415V - both 4 pole - controlled via VSD

The new IE4 motor pulls quite a bit more Amps than the existing IE2 motor

However when we checked the energy monitor over the weekend, the new motor used 80kWh's less over the same period and runs on average 10kw lower.

Could someone please explain how we are pulling more Amps but using less energy (kw)

Any advice/information would be greatly appreciated!

 

[wcaseyharman]

Why do you need to use the nameplate values? You’ve already said that the new motor is using less kWHs. A lower power factor for the newer motor would easily explain the higher current.
One of my mentors often said “Why calculate when you can directly measure?” which seems applicable in your case.

 

[davidbeach]

You don't pay for "amps", you only pay for the portion of the "amps" that is in phase with the voltage. The portion of the "amps" that is in quadrature with the voltage doesn't show up in a kW or kWHr reading. Amps went up but the portion in phase with the voltage went down.

When one this sentence into the German to translate wanted, would one the fact exploit, that the word order and the punctuation already with the German conventions agree.

-- Douglas Hofstadter, Jan 1982

 

[waross]

If your plant does not have automatic PF correction equipment the extra Amps may still incur a financial burden.
While you are not billed directly for the quadrature Amps the they do contribute to the penalties for a poor Power Factor.
If the PF is left uncorrected, you may easily pay more in penalties than you save in consumption charges.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[wcaseyharman]

KVAR charges depend on the individual utility tariffs. I think the utility I work for charges $0.001 per kVArh per the industrial rate schedule(nothing for residential and commercial) which is almost meaningless.

 

[waross]

I have seen penalties of over 80% of the consumption billing.
The PF was less than 10%.
In the early days, a standard penalty was 1% of the consumption charge for every % below 90% PF.
So, 80% pf would be (0% - 80% = 10% penalty.
Some tariffs were even more expensive.
Back then, the PF was a monthly average.
Now I understand that some utilities base their penalties on actual KiloVARhr consumption.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[jraef]

It’s being run from a VFD, the PF will be .95 regardless of what’s going on in the motor.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[zlatkodo]

The fact that the FLA (Full Load Amps) of the new motor is higher than that of the old one does not mean that the new motor draws more current than the old one.
You should only compare the actual running Amps of both motors rather than the FLA values from the nameplate.
Regards
Winding Design and Analysis