Inverter problem

[Doug B]

I’ve had an inverter on my pillar drill for quite a few years now it’s an IMO I-drive but just recently the display isn’t reading 50 (hertz?) it can be anything from 44 to 3 which it was today resulting in the drill bit turning very slowly.
Turning it on & off a few times uped the display into the low 40’s which was enough to get the job done but it’s been flashing ever since & the value has slowly been dropping, now in the mid teens.
Anyone know what’s wrong with it, it’s worked fine up until recently.

 

[flh801978]

Are you using the inverter just to give you 3 phase at 50hz or do you have a means of adjusting the frequency?

 

[Sideways]

I'd check the manual, possibly do a factory reset and reprogram it.
If you don't want to go that far at first, just read the parameters and check that everything makes sense / hasn't changed.
There are probably some read only parameters and a fault log that can be read back to see if anything odd has happened.
If you aren't into electronics and just bought this already setup and working, you have a decent learning curve ahead of you....

 

[Sideways]

By the way, if there is a potentiometer for speed control, those wear out and it may be a simple fault in the "pot" or it's wiring.
Inverters used without a pot for variable speed often have a simple wire link connecting two small terminals (the equivalent of a pot or volume control turned full on). If this has come loose, broken or corroded, it might cause the symptoms you are describing.
In either case, just replace like for like with a new one.

If an internal fault has developed, it probably won't be economical to repair. A new inverter will cost you £120 odd for a British made one or little over half for a Chinese one.

 

[Doug B]

Thanks for the replies.
I bought the inverter 6 years ago this coming January, it came with a station which gave on/off, speed control, forward/reverse & jog.
As I didn’t need to set parameters I just wired it up & it worked, I will try wiring out the potentiometer as I don’t use it, changing the belt works better for slowing the chuck as using the speed control on slow speeds loses torque.
I’ll dig the manual out tomorrow & have a read up, frightening how quick I can forget things I’m also now wondering if there’s an internal battery

 

[Sideways]

That all sounds sensible.

Just one caveat. A VFD provides overload protection for the motor. If you didn't buy this in a package with the motor, ready configured, then it has no idea if it's connected to a 1/2hp or a 1 hp motor. The overload protection by default probably assumes the motor is the biggest size that the IMO is capable of driving (may or may not be true), and is being used for general duty (true) so it will allow maybe a 50% overload for 30 seconds. If configured for fan or pump duty, a VFD might be factory preset to allow (say) 10% overload for an extended period but immediately shut down above 10% so you don't want either of those options !
If you can, I'd personally want to program the IMO with the actual "full load amps" of the motor you are using, just to be on the safe side.

Your use of the belts for proper low speed torque is excellent. Too many people don't appreciate that !

 

[Spectric]

Hi

If it's that old then just buy a new one and set it up for your motor size like Sideways has said. Not worth fixing because you start chasing failure modes, ie you fix this fault and next week a capacitor blows, then it suffers bitrot in the firmware so start afresh with a new branded one and get on and enjoy the woodworking not fixing the tools.

 

[Doug B]

By the way, if there is a potentiometer for speed control, those wear out and it may be a simple fault in the "pot" or it's wiring.

spot on with your diagnosis Sideways, thanks, basically the inside of the potentiometer had fallen to pieces, new one installed I just need to reinstate it all on the pillar drill which s tonight’s job.