626 mill motor/inverter mods

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russ57:
Terminology issue here, maybe, but what do you classify as 'supply side'? Everything I read says nothing to be connected between the output of the vfd and the motor, so that only leaves the' input, or supply side to the vfd. I'm not understanding how an nvr could be used on a control input.

-russ

appletree:
Hi sorry a bit of confusion here, I actually referred to NVR function as opposed to the unit itself.
I n the case of my inverter the start is a short making of the normally open "start" switch. The stop is a short breaking of the normally closed stop circuit.
Not that I have any interlocks on my machine as it is too old to have them as standard, if it did the would be in series with the stop button.
Hope this clarifies things.
By supply side i do mean the 240v input to the inverter.
In industry it is not permitted to derive safety interlocks from electronic data, it must be actual switches.
Try a couple of google searches, as always there is loads of info out there, I can't post links on my tablet.
Anyone else care to offer their two penneth Phil

philf:
Hi Russ,

On my lathe (same would apply to a mill) I have an NVR switch on the mains input to the machine. This prevents anything automatically powering up if there is a mains cut. If the lathe is running I wouldn't normally use this switch to stop it.

I also have start & stop switches connected via a latching relay. A spare set of contacts on that relay goes via a forward/reverse switch to the forward/reverse inputs on the inverter. The start and stop switches are used to start and stop the lathe. The correct decelleration and braking control is then applied to the motor. (As has already been mentioned - if you have a power cut and the lathe is running you don't have the advantage of controlled decelleration.)

Here's my 'crap-o-cad' circuit diagram: (Note to self - must get round to doing a proper cad drawing!)

The forward/reverse switch doesn't drop out the latching relay. I use this when tapping holes.

Chuck guard and change wheel cover switches are connected in series with the Stop button and unlatch the relay.

Hope this is of use.

Phil.

russ57:
Thanks guys, finishing up my mill install including Dro is high on my list of jobs for the year...

-russ

appletree:
Hi Philf
Post is a practical solution which covers most of the bases, and does the required. The NVR contractor provides people ultimate protection but as said is not the every day stop start option.
On my wood lathe the stop start is switches are wired solid on/off and no NVR protection whatsoever, when I did my Raglan Metal lathe I did a bit of head scratching and reading of the manual and did the job correctly.
My inverter is a Mitsubishi Frequal and I knew the facility existed but couldn’t find it how to do it, now I have worked it out I really ought to re-visit the wood lathe, using this set up the NVR function is provided by the inverter, no extra power supplies are required the inverter holds onto the last input signal until the power is interrupted, the safety contacts just go in the stop circuit.

Phil

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