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rotorhead:
I do let the Hz drop to zero before either swapping plugs(before mod), or switching over, as I thought there might be a conflict with the VFD.
But do I actually need to switch the power off to the VFD?
All and any input/info is very welcome, as I don't want to b*ll*cks anything up, funds are a bit tight now.
philf:
--- Quote from: rotorhead on November 15, 2012, 06:51:54 AM ---
I do let the Hz drop to zero before either swapping plugs(before mod), or switching over, as I thought there might be a conflict with the VFD.
But do I actually need to switch the power off to the VFD?
All and any input/info is very welcome, as I don't want to b*ll*cks anything up, funds are a bit tight now.
--- End quote ---
Hi rotorhead,
Yes, I would turn the power off to the VFD before switching from one machine to another. Better be safe than be sorry.
Just thinking that, if you use the VFD to stop the lathe, you made need to set a long decelleration time or connect a braking resistor to the VFD to dissipate the energy stored in the lathe.
Cheers.
Phil.
rotorhead:
Hi Philf,
As I'll be trying the soft start method now, that'll mean engaging the clutch before starting the VFD.
To stop, I can release the clutch, then switch off or turn the down Hz, thereby protecting both.
It's starting to get a little more complicated to achieve a more satisfactory result, but better safe than sorry, eh?
Having thought about this a bit more through the comments in this thread, am I using a realistic combination of 3Hp motor and 4Hp VFD as is, or do they need some sort of synchronizing?
I initially used a 3Hp IMO, but that was for a 1/2Hp motor on my Clarkson Mk1, seeing how well things went with that, I converted my lathe and miller to 3Ph aswell, using 3Hp 3000 rpm motors, and utilising a plug in system to use whichever.
Whilst not actually having any problems with that setup, I did think a bit more on the VFD size side might make things more tolerant.
philf:
--- Quote from: rotorhead on November 15, 2012, 09:33:08 AM ---Hi Philf,
As I'll be trying the soft start method now, that'll mean engaging the clutch before starting the VFD.
To stop, I can release the clutch, then switch off or turn the down Hz, thereby protecting both.
It's starting to get a little more complicated to achieve a more satisfactory result, but better safe than sorry, eh?
Having thought about this a bit more through the comments in this thread, am I using a realistic combination of 3Hp motor and 4Hp VFD as is, or do they need some sort of synchronizing?
I initially used a 3Hp IMO, but that was for a 1/2Hp motor on my Clarkson Mk1, seeing how well things went with that, I converted my lathe and miller to 3Ph aswell, using 3Hp 3000 rpm motors, and utilising a plug in system to use whichever.
Whilst not actually having any problems with that setup, I did think a bit more on the VFD size side might make things more tolerant.
--- End quote ---
Rotorhead,
A 4hp VFD will be more than man enough for a 3hp motor. There is usually a motor current setting on the VFD so you could probably set it for a 1/4hp if you wanted. There is always a factor of safety built in so it would, for some minutes, cope with in excess of 4hp. I guess you've already discovered this for yourself with your Clarkson with a 3hp VFD and a 1/2hp motor. You could probably make a few bob by selling the 3hp VFD and buying a cheap 1/2hp one for that!
Phil.
rotorhead:
Hi Philf,
I'll need to keep the 3Hp IMO especially for the Clarkson, as it's at the other end of my garage/workshop, the boss would have me sell it all, just to keep the swarf out of the house, dare say it would keep us both comfortable for a few months.
But then then I'd be under her feet, It'd be me to go next, even less expense for her.
Anyway thanks for the replies lads, you've all given me things to consider and mull over.
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