Motor Current Discrepancy

I cannot explain this from the information you've provided us. I suspect a difference in the wind inductance has lead to different power factor. Then again you might have made a reassembly misalignment that is leading to excessive bearing wear, too.

I would say you increased the RPM ...you might have a 50hz motor running on 60hz power supply...?

Did you try to discover the missing data by Goggling the mfg. motor number from the name plate.

Motor RPM? Frequency?

Provide adequate information for an informed answer.

These are all 50Hz motors with 50Hz supply, alignment is perfect. The only factors that are different are shaft diameter, maybe RPM may have changed from 950 to 990RPM.The new motor is a high efficiency motor.

Can these factors alone can cause the change in amps.

~ 12% increase in airflow could account for the additional power demand...it's possible there was some restriction in the airflow previously? ...or the rpm on the old motor was something around 870...or the fan blades were really dirty and have since been cleaned....

At the time of motor replacement, were any air passages also cleaned? If so, the increased air flow could explain (at least some of) the increased amperage.

This is a significant increase in power demand; (50%)

The only things I can think of that result in higher amps from one motor to the other are:

Increased load (air flow,bearings,alignment,etc.)

Improper direction of rotation?

Pulley size change or excessive belt tension, if belt driven.

Wrong frequency or voltage connection (wye,delta); double check connections on motor.

Is there a perceptible increase\decrease in air flow?

My first thought after reading the request was also that of wye/delta connection, followed closely by the outcome of the inevitable maintenance done on the air flow path and any screens aka cleaning.

Others already there with the descriptions.

Recalling P=VI= I²R, so R=P/I², the old has more resistance/impedance than the new by roughly 50%, so you better check do insulation test for both not operating and compare.

You may also look at P=Tω.

Casing or bearing housing to shaft alignment and preload condition might be different also. Types of bearing used between the old and new could also be an attribute.

Fluid dynamics of the work piece might also be an issue.

If the new motor is operating inside the full load current of the existing installation, can someone please explain why the <...We...> has a perceived problem to solve?

I was looking at this as a possibility as well, it seems this motor is only about 40% loaded....so the motor is over sized for the application... Ideally the motor should be loaded 60-80%....The power factor is probably <60 ....

https://www.energy.gov/sites/prod/files/2014/04/f15/10097517.pdf

Thank you, clearly aligns with our set up. Just to note, Everytime we replace these Hyundai motors with a new motor we notice a change in amps, it is more noticeable in this application, maybe due to the motor being oversized.

Amps is something Process people look at ,it is a challenge to change that.

"Amps is something Process people look at ,it is a challenge to change that."

Amps change not only with power factor, but also with voltage swings. I personally don't like using amps on a motor as a process value. Spend a few dollars more and get a kW meter. kW ALWAYS correlated to actual shaft power, which is meaningful no matter what other changes are going on. the nice thing now is that there are many "smart overload" relays that will give you an analog output proportional to kW, so rather than have multiple devices on the same circuit, you just swap out the OL relay for a smart one and get the info from that.

Industrial users of electricity have 3 charges:1 for KWH, 1 for KVAR(power factor),and one for Demand.

The billing is based on all three factors,with a steep multiplier for high demand and low power factor.

These used to be separate meters,but they are now recorded digitally and an instantaneous real time usage is available to the user.

Some older plants still insist on having the old analog meters in addition for verification.

Whatever the cause of the high amp draw,it is costing the company at least 50% more to run the new motor.

A small change in speed (because your newer motors have lower slip) will increase power consumption significantly for a centrifugal fan, the higher amperes is likely due to the higher air flow, due to the higher speed. Power factor may have some small impact on the observed amperes.

Quite. Power consumption varies with something like the cube of the impeller tip speed.

Why the <...process people...> are interested in <...amps...> is somewhat abstruse.

"A small change in speed (because your newer motors have lower slip) will increase power consumption significantly for a centrifugal fan, ..."

Excellent point. Yes, power required by a centrifugal fan increases at the cube of the speed change. So even a small change in slip speed will have an amplified effect on power consumption.

A 50% increase in current however would require a 14% increase in speed alone; more than just what you might expect in a slight difference in slip speed on a motor of the same pole count. It's likely a combination of a higher slip speed AND a lower power factor.