VFD Motor Terminal Heatup Issue

you're over your head, you should never expect to find remedies from an internet forum, call in a professional electrician who services VFDS

IS this an AC or DC motor?

If DC; Check motor brushes for wear, tension, and correct grade, check motor bearings for binding, and check motor windings for faults.

If AC; Check motor winding(s) for shorts and ground(s).

Look carefully at the rotor, stator, armature laminations for damaged insulation and/or burn holes regardless of whether the motor is AC or DC.

Make sure the VFD and the VFD programming are 100% compatible with the motor. (Is the Volts-per-hertz correct,? Is the frequency correct? Is the drive and motor HP matched? Is the output voltage of the VFD correct? IS the VFD input voltage correct? IS the VFD internally shorted or otherwise damaged.)

If you do not know how to do any/all of this, hire a competent technician or rent a reputable technical service company to troubleshoot the problem.

Good luck and stay safe.

No VFDs on DC motors. Maybe a PWMD....

There is no hope of you ever solving this problem. None.Since we know nothing of the VFD or motor, except the motor is ABB.

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Beg them for help.Be prepared with much more information.

Aluminium wiring is notoriously difficult to terminate and requires connectors etc specially made for joining aluminium.

The problem is progressive joint oxidation, which, as it progresses, reduces the current carrying footprint, which make more heat etc = possible runaway positive feedback.

This does resemble your problem, so you might need some help from a pro

I doubt this is the problem. OP sounds like he is getting a new installation to behave so oxidising isn't it (yet)

It's not hard to terminate, no notoriety, if performed correctly.

Crappy Al joints show up as localised heating.

I based my comment on these.

<<Still there is heat up of cable Heatup terminal box, it is found extended to winding leads.>>

I interpreted this to be heating causes by a high resistance connection being transmitted down the wires. These are substantial connectors

<<3.Put the bimetallic washers>>

this sounds like some aluminium to another metal connection, which merits extra attention.

It would be a good idea to use one of those RI thermal readers, or even a FLIR cam

Any and all aluminum connections need special attention, at any and all times. Even new connections that are not torqued correctly at installation.

It's really not a good idea to use a general purpose motor on a VFD since the insulation cannot handle the voltage spikes. Replace it with a VFD rated motor that conforms to the IEC 61800 series, particularly IEC 61800-4.

Just to confirm, you now have 9 x 240mm2 ( 3x 720mm2 per phase equivalent ) and the cable is still cooking?

Have you tried a DOL start to see what happens?

What size Trafo/genset are you using?

1. IT IS VFD MOTOR(MOTOR IS DESIGN FOR VFD APPLICATION)

2. FAN APPLICATION.

3. VARIABLE SPEED IS REQUIRED,SO WE ARE USING VFD DRIVE.

4. TAKING NORMAL CURRENT i.e. BELOW RATED CURRENT.

5. DOL IS NOT POSSIBLE

why are you screaming?

NOISY bugger!

https://en.wikipedia.org/wiki/Variable-frequency_drive

Have a look at all the citations at the end as well and you may find your answer written in one of those. All sorts of issues discussed. I can't read it for you, sorry, it's your sick baby.

D, have a look at these from a CR4 previous thread

http://jmst.ntou.edu.tw/marine/18-2/290-297.pdf

http://www.cired.net/publications/cired2007/pdfs/CIRED2007_0275_paper.pdf

I NEVER recommend using aluminum conductors for running out to motors from VFDs. It is BEGGING for trouble. I do not know of a single VFD manufacturer who does not say that the motor leads should always be copper. I also do not know of a single manufacturer of VFD rated cables that uses aluminum.

One of the main problems with the connections between VFDs and motors is what is called the "reflected wave" phenomenon. This is a capacitive coupling effect in the adjacent conductors because of the high speed switching of the transistor pulses, which causes a voltage to be expressed on the conductors on top of the normal voltage, a "standing wave" if you will. That standing wave travels down to the first point of an impedance mismatch, usually the motor terminals, and bounces back, called "reflecting", where it then adds to the next wave coming at it and increases. The potential on those reflected wave spikes eventually increases to up to 3x the line voltage and breaks down the insulation in the motor windings.

But long before that happens, that first point of impedance mismatch is also the first place the problems begin. Most if not all VFD rated motors will have copper windings. Aluminum has a lower natural impedance than copper so it more easily passes higher frequencies present in the PWM output to the motor. But because the copper windings will have a higher impedance, that not only makes the standing wave creating more likely, the junction also BECOMES the low pas filter (of sorst) for the higher frequency harmonics, "filtering" them by turning them into heat. Using aluminum conductors almost GUARANTEES that there will be a sever impedance mismatch at the motor terminations, and sever heating.

RTFM...