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Replacing 500V Motor With a 400V Motor

04/11/2017 9:15 AM

I have a 3 Phase AC SC induction motor which drives an EP Fan (Exhausts gases of electrostatic precipitator) of a cement plant. Motor rating is 500V, 355KW,490A. Motor is driven by a frequency drive (ABB ACS 800 Series). We have 6300V (MV) & 400V (LV) voltage system at our plant. I want to replace this motor with a new motor of exactly same power rating (355KW), but with voltage rating of 400V,610A. My drive can supply 380-500V to the motor. Can i do it without any problem? Is their any thing to take care off doing this?

The distance (Cable Length) from drive to motor terminal is about 60 meter.

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Pathfinder Tags: 400V 500V AC Induction motor replace
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#1

Re: Replacing 500V motor with a 400V motor

04/11/2017 9:21 AM

For what the replacement motor is worth, the supplier will not only do the maths for you, but give a warranty on the outcome.

Please discuss this with your motor supplier for clear understanding and professional support.

If you are concerned about their response, then send it to the Frequency drive supplier for their confirmation.

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#2

Re: Replacing 500V motor with a 400V motor

04/11/2017 9:23 AM

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.

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#3

Re: Replacing 500V motor with a 400V motor

04/11/2017 10:05 AM

From 490A to 610A is almost a 25% increase. Do you really think the original motor cable was oversized that much?

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#4

Re: Replacing 500V motor with a 400V motor

04/11/2017 10:19 AM

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.

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#6
In reply to #4

Re: Replacing 500V motor with a 400V motor

04/11/2017 10:39 AM

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.

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#7
In reply to #4

Re: Replacing 500V motor with a 400V motor

04/11/2017 10:42 AM

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

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#9
In reply to #4

Re: Replacing 500V motor with a 400V motor

04/11/2017 11:37 AM

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?

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#18
In reply to #4

Re: Replacing 500V motor with a 400V motor

04/12/2017 12:40 PM

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.

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#5

Re: Replacing 500V Motor With a 400V Motor

04/11/2017 10:34 AM

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

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#8

Re: Replacing 500V Motor With a 400V Motor

04/11/2017 11:15 AM

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.

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#16
In reply to #8

Re: Replacing 500V Motor With a 400V Motor

04/12/2017 3:17 AM

500V was used in mines and quarries

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#22
In reply to #16

Re: Replacing 500V Motor With a 400V Motor

04/13/2017 6:16 PM

"500V was used in mines and quarries"

Learned something new today... thanks Tony!

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#10

Re: Replacing 500V Motor With a 400V Motor

04/11/2017 11:57 AM

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?

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#11
In reply to #10

Re: Replacing 500V Motor With a 400V Motor

04/11/2017 1:00 PM

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.

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#12
In reply to #11

Re: Replacing 500V Motor With a 400V Motor

04/11/2017 1:59 PM

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.

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#13

Re: Replacing 500V Motor With a 400V Motor

04/11/2017 10:59 PM

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.

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#14

Re: Replacing 500V Motor With a 400V Motor

04/11/2017 11:54 PM

Yes i understand that we have to reprogram the drive as per new motor data and execute an ID Run of the motor after feeding new motor data. Drive can support 400V motor, so thats not an issue. I will write to our plant manufacturer about this design. If i get an answer from them, i will surely post it here.

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#15

Re: Replacing 500V Motor With a 400V Motor

04/12/2017 3:06 AM

You have to further check the rated current carring capacity of your installed cable and it's suitability for 610 A application. Also check the current delivering capacity of the VFD because the VFD must have the capacity to deliver current of 610 Amp at 400 V.

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#17

Re: Replacing 500V Motor With a 400V Motor

04/12/2017 11:19 AM

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

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#19

Re: Replacing 500V Motor With a 400V Motor

04/13/2017 12:31 AM

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.

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#20
In reply to #19

Re: Replacing 500V Motor With a 400V Motor

04/13/2017 11:49 AM

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

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#23
In reply to #20

Re: Replacing 500V Motor With a 400V Motor

04/17/2017 6:44 AM

haha. true

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#21
In reply to #19

Re: Replacing 500V Motor With a 400V Motor

04/13/2017 12:54 PM

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.

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