YL620 VFD Drive stopped working on my 2x72 Grinder

D

DSB123

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Hi All,
Hoping for some help and pointers here if at all possible. My 2x72 belt grinder has stopped working. I tried to use it today and it will not start. I have a YL620 VFD wired up to a potentiometer and until today everything seemed to be working great. Today the main display on the VFD is flashing and FOR light is on. When I turn the potentiometer (remote) the display shows increasing frequency but the motor on the grinder does not start at all. Not sure where to start looking. The ambient temperature today is low and the grinder is in my garage - could it be the low ambient temperature that is the problem? I am new to VFD's.

Thanks.
 
Is there a factory reset button somewhere on the unit? Unfortunately these things are too complex to repair unless you have a bench full of electronic test gear and schematics and even with that, getting replacement parts and soldering surface mount devices is enough to discourage anyone
Is the unit recently purchased? Your credit card company may be able to get your money back
-M
 
The flashing "FOR" makes me think that the VFD is unhappy about something regarding the load. Try disconnecting the motor and turning on the VFD. Does it do the same thing? Also, check the motor for continuity. You should see something like 10-200 ohms, but not infinite and not zero.

If all that is as expected, I think it's time to buy another VFD.
 
Is it possible grinding dust got in there? If so, it's probably shorted something out. You could try to clean it, but that sort of thing usually fries transistors. I use a similar unit on my machines, but I remote mount the VFD to keep it away from dust. Cold shouldn't bother them, if anything solid state electronics generally prefer being cold.

Try the other suggestions. Perhaps try starting the motor by hand, keeping your soft bits clear. I suspect it thinks there is a problem and isn't even trying to apply output. You might also try removing the remote control wiring and using the keypad on the VFD to test.
 
KB may have a point there- if one of the motor phases goes open circuit the VFD might shut down to protect itself- check motor wiring and motor
-M
 
IN addition to checking the resistance of the motor coils, also check from the motor wires to ground for anything that might have got grounded.

Gently use compressed air to blow out the VFD and the motor to get rid of any accumulated grinding dust.

How old is the motor on the grinder? Some of the older motors do not like Inverter power.
 
Hi All,
Thanks for the responses. The Motor is newish - i bought it in July last year from a manufacturer in Germany. The VFD is located in a Casing I made out of Plywood. I will do the checks indicated in your responses and revert back.

Regards

Denis
 
Does the plywood casing have adequate ventilation to allow the VFD cooling air? Do you have filter elements over the vents to keep the grinding dust out?
 
Hi All,
Yes the plywood casing has a vent at the bottom, fitted with an induction fan (not connected since not sure how to do that) and a outlet at the top of the casing (for exhaust) , Both inlet and outlet are fitted with filters. I still need to do the checks above - too cold in the garage to mess around at the moment. Let you know what the checks throw up when it gets a little warmer.

Regards

Denis
 
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