Replacing 500V Motor With a 400V Motor

The reasoning behind not using the telephone to contact ABB directly, and posting here instead, would come as a great enlightenment to all the sleeping beauties at CR4. Do, please, explain as it would fill the readership here with great awe.

I have two other motors of same rating except that their voltage is 400V. I want to buy a 400V motor against all these three motors. Thats the worth.

If my transformer gets faulty I will be able to supply the frequency drive with my 400V power supply. Thats the worth.

Motor manufacturers can assure the motor specs, and drive manufacturer do the same for drives abilities.

Reason for posting it here that I cant understand the design for putting this one 500V motor where all other motors are of 400V.

Is the 500 V motor stating 500 V as an upper limit for the windings insulation? Is the 400 V motor the same power, less power, the same?

Sounds like you are wanting to someone to pass on a blessing to take a shortcut. We are not here for that, you hear?

Current through windings is what produces the magnetics the motor depends upon. You may not be able to produce sufficient current in a 500 V motor if the winding resistance is greater than for the 400 V motor, depending on what was designed initially for the site, or if this is merely jury-rigged.

<...transformer gets faulty...> Why would that happen? Inadequate maintenance?

The only way to understand why this particular motor is 500V and the others are 400V is to talk to the people who did that reasoning when the equipment was designed and originally purchased.

Is there some reason why a strategic spare motor of the correct voltage and capability of being a 1-for-1 swap for a dud one is not currently available? Budget cuts, for instance?

Is there some reason why motor protection circuitry is so inadequate as to ensure the longevity of the 500V motor that a failure is likely to occur? Budget cuts, for instance?

Is there some reason why the surplus 400V motors cannot be realised on the open market to raise the purchase price of the correct 500V one as a strategic spare?

500V is a common voltage for a dc motor. It sounds like a mistake, then executed upon. How old is the installation?

The 400V solution makes sense.

Use the telephone, and you will cover the required miles much faster. Motor supplier should have a wealth of information on this.

500V is not an AC motor voltage standard I have ever seen. So someone would have had to have some very specific reason to have ordered this as a special, which means you need to be doing a VERY detailed investigation of EXACTLY how it is being used and why.

500V is, however, a very common DC motor voltage. Make sure you are reading the nameplate correctly.

500V was used in mines and quarries

"500V was used in mines and quarries"

Learned something new today... thanks Tony!

I think you may need to rethink the electrical supply to the motor when switching to the lower voltage motor, such as (1) make sure the MCC can handle the extra current, (2) that the breaker upstream of the VFD can handle that current, and (3) the cabling to the new motor may need to be increased gauge to handle the current without heating issues.

What did ABB have to say about your set-up? Still have not called them? Why?

Yes I contacted ABB. They said they assure that there will be no problem with the drive as below as 380V motor. Motor is of siemens.

What is the absolute upper potential limit to be applied to this new motor, 400 V? No higher?

If 400 V is a hard limit, you really don't leave a lot of wiggle room in the set up.

Caution - <...they...> cannot say anything about the site cabling! Consult a qualified local Electrician, who will be able to calculate, advise, install, test and certify as safe on completion.

Drives out put should not be more than 400 volt for 400 volt motor. For proper torque and RPM control VFD to be re-programmed and put name plate details of the motor in the programe. Moreover the motor should be VFD compatible.

Provided the VFD and the cables can handle the higher current (up 25%) should be OK IMO, but worth checking with ABB.

Just an idea hit my mind. Can I ask my motor manufacturer to make me a common spare motor having current capacity (conductor dia of 720A as of 400V motor) and insulation level as per 500V motor (no issue of current as it will be less).

It can be installed against any of two motors in case of emergency.

Is this possible. I think yes.

Usually, the asking does not cost much if anything. It is the acquiring that costs.

haha. true

Mechanically it may not fit your install conditions for all motors, but if your 400V motors fit where the 500V motor is, you should be good. The internal motor insulation is unlikely to change, but you will need more room for copper, and bigger rotor bars.