Thread: Two GMFs and one VFD

Originally Posted by Stustoys

And yet no smoke was released!
I wonder just how much of this sort of thing these VSDs will really put up with.

Stuart

Just to prove the first time was not a fluke I did it twice more AND only then I realised I probably had not switched that VFD to coasting stop.
Still no smoke

I really gave those interlocks a bit of a work out.

I spent most of yesterday rearranging the bench grinder attachments, which is really just another version of rearranging the screwdrivers, just a lot slower.

Now the 2 variable speed GMFs have the following
One the gold coloured GMF there is the
- thin kerf cutting disc saw and a
- green wheel

On the green GMF there is the
- CBN wheel and a
- multitool linisher

The linisher was on a 1Phase Abbot and Ashby but I wanted it mounted onto one of the variable speed grinders.
The mounting was a bit of a pig because two bearing locating screw heads interfere with the multitool mounting and of course the GMF has longer shafts so I can't attach the outer multitool sanding disc base because the shaft pokes through the space. To get around this I could pack out the multitool base but 'm just leaving this because I don't use the disc anyway as I have a 12" disc on another.

The Abbot and Ashby (which my brother gave me a few years ago sans guards and flanges) is a grunt little grinder and now has a new 8" Scotchbrite wheel and a wire wheel. Mounting the wire wheel needed new flanges made as the residual GMF flanges are too thick for the A&A shorter shaft.

The variable speed Atkins pedestal grinder will become an actual grinder and the old 10" can be disposed off - hey I'm actually getting rid of something from my shed

During the process I have been using the cross over switch between the two GMFs and in general it works very well HOWEVER, one thing I discovered was.

Grinder A running, turn of VFD, quickly switch cross over to grinder B - ALL good (note grinder A still coasting - from full speed it will coast for several minutes)
If I now switch back to grinder A (still coasting at relatively high speed) the VFD of course wants to start/run under a controlled ramp so it rapidly decelerates Grinder A and this can loosen the wheels

All part of a learning curve and hopefully useful for other folks that want to do this,

Originally Posted by BobL

If I now switch back to grinder A (still coasting at relatively high speed) the VFD of course wants to start/run under a controlled ramp so it rapidly decelerates Grinder A and this can loosen the wheels

Have you tried using PD025=1?(including pd032,33 and 34)

Stuart

Originally Posted by Stustoys

Have you tried using PD025=1?(including pd032,33 and 34)

Stuart

No I haven't but reading the manual suggests it is a good idea.
Even if you have one VFD and one high inertia load machine.

Any idea what reasonable settings would be for PD32-34 - go with the factory settings for a first up?

Originally Posted by BobL

Any idea what reasonable settings would be for PD32-34 - go with the factory settings for a first up?

Sorry Bob cant be any help there. To long ago and it was only a "play" I'm not sure I came to a conclusion. Good luck

Stuart