induction motor getting hot help!!

[accyjoiner]

i bought a nice new table saw last year and have only just managed to find a 400mm blade to fit it but when i use it with the big blade it takes a good few seconds to get up to speed and after using it for maybe 10 mins the arbour got hot never mind the motor and this has never happened using blades up to 305mm i don't know if maybe the blade is too thick or the capacitor is bad or what but im frightened of using it now lol its an old one from 1976 called a susemihl su300hns anybody got any ideas? is this normal with an induction motor? i thought they were meant to run cool

 

[Rorschach]

How hot is hot? The induction motor on my lathe gets hot too hot to keep your hand on comfortably, but that doesn't mean there is a problem.

 

[accyjoiner]

well like i said much hotter than when i use smaller blades 210 to 305mm

 

[Rorschach]

If it doesn't happen with the smaller blades then I would say you are overtaxing the motor with the larger blade.

 

[accyjoiner]

it says it will take a 400mm blade so i cant understand it

 

[CHJ]

Does the motor/Blade assembly spin freely by hand?

Are you sure that when fitting new blade you have not managed to get something misplaced and causing friction/fouling?

If Motor is running slow due to friction, excessive current flow in windings will generate heat. (motor needs to run at full speed to control current input)

Does the motor have centrifugal starting switch or is it a simpler one just fitted with start/run capacitor permanently in circuit..

 

[accyjoiner]

the blade is attached to a flange and that is attached to the arbour via a taper so i dont think i could misplace it without the blade running noticeably out of true so i don't think i have as for the centrifugal switch i have never heard a click so i don't think so and it's only got one capacitor

 

[CHJ]

the blade is attached to a flange and that is attached to the arbour via a taper so i dont think i could misplace it without the blade running noticeably out of true so i don't think i have as for the centrifugal switch i have never heard a click so i don't think so and it's only got one capacitor

If the slow start-up was due to capacitor failing, it should not result in significant excessive motor heat when running no load, if the motor slows down due to insufficient torque due to faulty run capacitor when in use though, then the consumed current will increase.

 

[accyjoiner]

ok i will get an amp meter and check it out does anybody have a 400mm induction motor table saw so i could compare motor temp/running amp thanks

 

[user 26031]

I'm not familiar with the machine, but if you have a capacitor, it must be single phase, yes?
It strikes me that a 400mm blade could be too large for a single phase motor.
My old PKA swung a 16" blade an that had a 7 HP 3 phase motor.

 

[accyjoiner]

its what is on the label 400mm max its an induction motor with a capacitor single phase i'll have a look at label another day its buried in the shed haha

 

[dzj]

I'm not familiar with the machine, but if you have a capacitor, it must be single phase, yes?
It strikes me that a 400mm blade could be too large for a single phase motor.
My old PKA swung a 16" blade an that had a 7 HP 3 phase motor.

Yes, for a 400mm blade you need at least a 4HP motor. Probably more for ripping. Not for single phase in any case.

 

[accyjoiner]

i can't see a company a german one at that manufacturing a saw underpowered for the blade that it is designed to use especially one from back in the day machines used to be built like tanks back then haha

 

[dynax]

only a guess but is it possible it's a dual voltage motor wired up for single phase and for using the bigger blades needs to be wired for 3 phase,

 

[accyjoiner]

arent all induction motors capable of running on 3 phase? anyway it says 240v on motor so i don't think thats it i'll have a look now cuz its bugging me haha

 

[accyjoiner]

turns out 240v isn't on the motor neither is any voltage so it is possible is there any way of finding out?

 

[dynax]

probably have to open it up and see what terminals are in it,

 

[accyjoiner]

upon further inspection i can't see any way of altering the wiring like that on a 3 phase machine so i don't think that it is dual voltage

 

[dynax]

maybe worth looking on some electrical forums and see if anything on them can shed some light into the cause,

 

[Myfordman]

Motors can be single voltage and dual voltage and either single phase or 3 phase but never ever configurable between single and 3 phase.