A strange fault and a interesting days fault finding....

[Darkwood]

Its possible the slider hadn't been pulled across fully and only just making contact.

The O/L will be by-passed because thats what your inverter is designed to do unless it covers multiple motors.

As for the motor connections, if you are right is it possible the drive parameter have been set for overspeed because the previous connections may has run it slow and they tried to fudge the speed using the drive.. get a parameter list and check max speed is set at 50hz ... if what you say as all correct it does sound like someone has been fiddly without understanding - it is also possible one of your drive inputs has broken down forcing the drive to slave off 2 phase but this shouldn't effect the output in such a manor as to overspeed it... what make of drive and model is it? - there are simple ways to check the drive with a few command changes.

Your drive will more than likely have external command cues for speed, run stop etc ensure you are aware of all the inputs/outputs and how they work before finding a replacement... speed control can be done with various methods and usually 0-10v or 4-20mA source so check you understand it and whether the control is set as PNP or NPN. Even an identical replacement of the drive may be useless if you cannot configure it and set it up.


If I was you I would do a full disconnect test of the motor without the shorting out termial links in place for IR and winding resistance to ensure it tests out ok, if the motor is small enough you could rig it up DOL to confirm it works without the drive and clamp the phases to check for balance.

I would get the motor plate details and confirm the motor is what you believe it to be (Star/delta) motor... trust me when I say they can be very confusing if you don't know what to look for on the plate other than the basics and even worse when plates are missing, can you get pic of the plate?

 

[Tiny Spark]

Thanks DW.
Cant run her up DOL as its a pretty hefty motor.
I took a pic of the plate but afraid its not great, very dark inside!!



I did a full test of the motor yesterday which was fine.
Hopefully still is!

I did wonder if there was some parameters wrong on the thing causing it to go into over drive.
But as said before i know naff all about drives.
Not to mention I have no paperwork for them.

This is the drive details if its of any interest to you:

 

[Knobhead]

Sorry not read through all of this but a motor driving a fan is liable to “windmill” while idle due to natural draft. Apply 2 phases to a rotating field and the motor will create its own artificial 3[SUP]rd[/SUP] phase and accelerate to more or less normal speed. The O/L’s should have detected this so you’ve several problems.

TS you know where to look for motor testing.

 

[Tiny Spark]

Well I am rather happy to say that today we managed to sort this piece o crap out.
So we original went to this thing with the POV that it hadnt run in a while due to some fault nobody had fixed.
As it turns out there is no way in hell this thing had ever run properly in the condition it was in, Which is very probably when it was modified to be inverter driven.

The final list of faults (and I use that term loosely) is rather long, So we came away with the POV the guy who mod'd it was a flaming idiot who had no idea what he was doing!

Highlights of the problems include:

Burnt out Dis Board
Burnt out breaker
Incorrectly programmed or U/S inverter (not really sure whats up with it)
Incorrect wiring between the Inverter and the Motor
Incorrect wiring of the Motor windings

So thanks again for your time DW, Was extremely helpfull and as usual I learned much from this episode.

Tony, Thanks for the reply, There was no chance of it windmilling but I do know what you mean, Used to have that problem with the air con units at my old site.

 

[Darkwood]

If all your peers at work are old gits then I bet one of them has a lot to answer for but I dare say they will be keeping stum about it all .... :38:

 

[Tiny Spark]

Lol well from what the elders say the guy who probably did the work left a long time ago.

Apparently he was also a muppet.

Not that i would guess or anything

 

[silva.foxx]

Well I am rather happy to say that today we managed to sort this piece o crap out.
So we original went to this thing with the POV that it hadnt run in a while due to some fault nobody had fixed.
As it turns out there is no way in hell this thing had ever run properly in the condition it was in, Which is very probably when it was modified to be inverter driven.

The final list of faults (and I use that term loosely) is rather long, So we came away with the POV the guy who mod'd it was a flaming idiot who had no idea what he was doing!

Highlights of the problems include:

Burnt out Dis Board
Burnt out breaker
Incorrectly programmed or U/S inverter (not really sure whats up with it)
Incorrect wiring between the Inverter and the Motor
Incorrect wiring of the Motor windings

So thanks again for your time DW, Was extremely helpfull and as usual I learned much from this episode.

Tony, Thanks for the reply, There was no chance of it windmilling but I do know what you mean, Used to have that problem with the air con units at my old site.

So have you connected the motor in Delta now, as per motor plate?




The Vacon manual can be found http://www.crtd.co.uk/ac-drives/vacon-nxl.php

Ensure parameters P2.1.6 thru 10 match the details of the motor plate.

 

[Tiny Spark]

Thanks for that Silva ile keep that handy for next time.
And yes it was rewired to Delta.