VFD and Surface Grinder Table Question.

I have a Reid 618V which has two motors that are three phase. My question is about the table. When in auto mode the table had a limit switch to reverse the polarity to change direction of the table. Can the limit switch be hooked to the VFD FWD/REV be hooked to the limit switch to control the table? Thanks in advance for your help.

Will


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Surface grinder single phase conversion, thoughts?


The 1/6th hp feed motor (which sounds like its designed for plug reversing constantly) is.. i'm speculating here: likely a special motor designed with a high slip to avoid jerking the table at every reversal, as such it probably does not draw 6 times its full load amps at startup.

If you are intending to run this machine from a single phase supply and need a vfd to drive it, i would buy a 2 hp VFD and plug it in and run it. even if the 1/6th hp motor draws 6 times its full load amps as is usual for an induction motor at startup or plug reversal.. you will probably not overload a 2 hp vfd doing so, unless you are already overloading the 1 hp spindle.


I would be more concerned about the vfd's common mode voltage destroying the spindle bearings (on a very long timeline) than worrying about the feed motor tripping the vfd.. which it shouldn't. (buy a 3 hp vfd if your time is worth money, they aren't that much more expensive than 2 hp single phase input vfds)


If you run the machine from a static phase converter (which is really just a motor starter, they are not actually sources of 3 phase power) the 1 hp spindle motor and the 1/2 hp coolant pump may be enough of a "rotary phase converter" in themselves to drive the table feed. but i wouldn't bet on it. you would also have to derate the spindle to 1/2 hp actual output, and that is hard to measure.

I was thinking of running two separate VFDs and controls for the spindle and the table. This SG does not have a coolant pump so I am not worried about that. My concern is getting the table feed to work with the BFD and if the limit switch can control the VFD to change directions.


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Yes you can use a limit switch to tell a VFD to reverse direction. But is your table motor 3 phase?

Yes, the table motor is three phase.


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