- Thread starter Jacktegla
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Hopefuldave
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Yep, no problem - low volt connection bottom left of the label, 240 in and out VFD capable of 2.2kw (3HP) and 9.5 Amps as per the label (if going with a Chinese budget VFD get a bit higher rating).
You need to wire the VFD output direct to the motor, no switches etc in between, and do a simple bit of rewiring to make the machine's forward/reverse connect to the VFD's control inputs, possibly make up a control box for speed control BUT speed control is no substitute for the machine's own gearing / belt pulleys, a VFD gives progressively less power as you reduce speed, no point having it turn a spindle at 10 RPM when a gnat can stall it!
Dave H. (the other one)
You need to wire the VFD output direct to the motor, no switches etc in between, and do a simple bit of rewiring to make the machine's forward/reverse connect to the VFD's control inputs, possibly make up a control box for speed control BUT speed control is no substitute for the machine's own gearing / belt pulleys, a VFD gives progressively less power as you reduce speed, no point having it turn a spindle at 10 RPM when a gnat can stall it!
Dave H. (the other one)
Good point about the low speed torque , also if there is a cooling fan in the motor running it at to low an rpm wont cool it enough , it's mostly ok for short periods but running it to slow all the time might cook the insulation (if I had to guess I would say half speed would be fine but check the motor case temperature when your running it.)
Seadog
Save the planet. It's the only one with rum!
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Just to clear you up on one point, it's not single or 3-phase. Just because it says 230v it doesn't mean single phase. It will be 230v 3-phase with delta connection or 415v 3-phase with star connection.
You alter the winding configuration in the terminal box to suit your supply voltage.
Hopefuldave
Intergalactic pot-mender
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Good point about the low speed torque , also if there is a cooling fan in the motor running it at to low an rpm wont cool it enough , it's mostly ok for short periods but running it to slow all the time might cook the insulation (if I had to guess I would say half speed would be fine but check the motor case temperature when your running it.)
Most VFDs have relay outputs you can use, look in the Book of Destructions for "supervisory frequency" or similar as a setting, and how to set the relay to open above it (so the fan's powered below the configured frequency AND when the motor isn't running / VFD isn't powered - the fan switches through the normally-CLOSED contacts) - I set mine to 30Hz and use it to switch an external sock-blower OFF when it gets close to normal RPM and the motor's fan can take over. Having it run when the motor's stopped reminds me to switch off when I'm done, helps with senior moments
Dave H. (the other one)
Most VFDs have relay outputs you can use, look in the Book of Destructions for "supervisory frequency" or similar as a setting, and how to set the relay to open above it (so the fan's powered below the configured frequency AND when the motor isn't running / VFD isn't powered - the fan switches through the normally-CLOSED contacts) - I set mine to 30Hz and use it to switch an external sock-blower OFF when it gets close to normal RPM and the motor's fan can take over. Having it run when the motor's stopped reminds me to switch off when I'm done, helps with senior moments
Dave H. (the other one)
Ah sorry , I was a bit vague , I'm talking about a built in fan on the rotor of the motor, I have only noticed this (had warming issues) when using very large hole saws and trying to go very slooooow on the mill.
Your point about a secondy source of cooling is a good point
Hopefuldave
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No prob, I was probably going a bit outside the thread - I know the Chinese import Blidgepolt mills that come with VFDs often have a middle-sized fan bolted to the top of the motor, the small mills with DC motors often have the same problem but they skimp the couple of quid for a fan so they die pretty quickly when run at low revs and high torque - the motor shorting out then takes out the speed-control boards and leaves a repair bill in the hundreds. Why I always recommend putting a cheap PC fan or better on the brush end of the motor!
Dave H. (the other one)
Dave H. (the other one)
duncans
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let me know if you need a 3hp 2.2 VFD mate as I've got one in my shed its the mini one if any good to you it's boxed with instructions but better off finding the correct perimeters out for your needs
