Motor FLC

[jimmy mustard]

Anyone know for sure what the FLC of this is

 

[Bobster]

Most probable guess, 30Kw so at 415v from the data plate 53A

These numbers tie up roughly, an educated guess only. Does the control gear lend itself to be a motor this size? Can you clamp the motor whist running to check?

 

[jimmy mustard]

I was thinking 30hp 44A but not sure. Its on a 63A type d 60898 which trips depending on the product its stirring.
Im trying to find out if its the correct size motor for the task ( or product)

 

[Bobster]

I think the 44 would be an IP rating

 

[Darkwood]

30HP would be about 22kw giving FLC 38-45amp, if this is the case and its is DOL or Star/Delta starting then I'm not surprised its tripping a 63amp mcb, such a motor started with such methods could warrant its own HRC fused supply and not tapped of a dist' board, knowing all the motor and control characteristics is key to knowing if an mcb is suitable.

Need more info, like has been mentioned, check what controls the motor and what size O/L protects it and this should give you an idea.

Also need to know the history, has the motor always done this job, is the product the same as before or has it changed recently to a stiffer mix, does the motor start under load or is it presented to the mix after starting, when exactly does the mcb trip...start up or after running a while?

 

[jimmy mustard]

I need the flc to begin with then all the rest is based on that. The medium is more viscous than it was when the motor was first installed

 

[jimmy mustard]

Plus it only trips on the higher viscosity product which makes me suspect the motor is too small for the job

 

[Darkwood]

You said the mcb trips, this has nothing to do with FLC and if the motor was too small for the job then the motor O/L would trip.

If it is a 30HP / 22kW motor starting on load then I'd need a lot of questions answered before running it off a MCB as the initial inrush spike can cause it to trip even on a type D whether it be DOL or the change over spike on a star/delta starter, the increase in viscosity will increase the likelyhood of the front end device tripping but won't neccesserally mean anything is wrong.

You need to check out the overload protection for the motor in the controls if the plate cannot be fully understood and also how the controls start the motor as this may change the value of the O/L required which may not match the motor FLC.

Have you clamped the motor for running load
What is the nature of the control system and starting characteristics

Questions like this are crucial to understanding what is happening and causing the tripping but like I said if the KW/HP is correct then supply design is crucial to avoid nuisance tripping, down time costs money and this shouldn't be because it has been installed incorrectly.

Just as info', Schneider tabulates a 22kw motor with a starting time up to 10seconds would be ok on a 50 or 63amp(d)

This is on the assumption the motor is 4pole, I am not sure of your motor speed but wonder if the 985 is the rpm?...this would make it a 6pole, to further help you it may be a good idea to check rotation speed too.

 

[jimmy mustard]

I need to know the flc to make sure everything else including cable size is correct for the motor then it comes down to load.
Its a star delta start and yes a bs88 would be better but it wont get changed , theres too much paperwork and redtape to get through for that to happen.
The mcb could be undersized this is why i need the flc

 

[jimmy mustard]

As for rpm until i get a tacho im guessing 985 is the speed

 

[Darkwood]

As for rpm until i get a tacho im guessing 985 is the speed

I suspect been a stirer of some nature then the motor will be geared down substancially, if it is a 6pole then it will have a higher torque available then a 4 pole and with the gearing on a 22kw motor you would have some pretty substantial available torque at the tool end - may I ask, what the hell is it stiring??? :dizzy2:

 

[jimmy mustard]

Theres no gear box and its actually a shear disperser to disperse powder in a latex product that is quite thick.

 

[Darkwood]

The more info the better, is the latex product been left stood for a while, does this unit trip more often first thing in a morning or is it regular throughout the day.. what I am getting at is, is it possible the product is caking up / solidifying on the shear head but once its loosened and broken free the shear starts up ok then until next time its left with mix to harden on it??

 

[jimmy mustard]

The product doesnt harden or cake up, the motor will run for maybe 30 mins - 1 hr before the mcb trips and at this stage the temp on the side of the mcb is around 90 degs C

 

[Darkwood]

If there is a motor O/L in the circuit then check this works by turning it down as low as you can if possibel, check current flowing through it isn't higher than its setting, it could be faulty, welded closed if its been subjected to a fault.

Check the current been drawn through the mcb, if this mcb is getting hot at no where near its rating then you have either conducted heat from adjacent high loaded mcb's and you are getting a runaway heat effect or a loose connection be it external to the mcb or integral to the mcb or board.

I would change the mcb and if possible relocate its position to ensure the heat isn't been transferred from problems with the board itself.

You have given us the 'at a guess' FLC of the motor, is their other loads on the machine that could mean this mcb is overloading below it tripping curve hence building excessive heat up.