Latching circuit? Is it necessary

[frijoli]

Normally equipment I work with has an "on" circuit. Meaning even though everything is powered up, you can't start it until you push the on button, then you have to press start as well.
That way if you have a loss of main power it won't restart automatically when the power comes back on.

Should I add a latching circuit or is the reset in Acorn sufficient to do this from a safety standpoint?


Clay

[RayL]

From a safety stand-point, a "magnetic switch" is the best, as it is impossible for it to turn itself back on. Softwaare can misbehave, normal switches can fail in an open or closed state. A good magnetic switch, once turned off, simply cannot turn itself back on. And, they are not expensive.

Regards,
Ray L.

[DICKEYBIRD]

From a safety stand-point, a "magnetic switch" is the best, as it is impossible for it to turn itself back on.

+1 on that one. Coincidently, I'm wiring up an A-B contactor with 24vdc coil for the new mill as we speak. An easy circuit but it gives me fits every few years when I have to do one and it's long since been forgotten. I got it done by looking inside the ORAC's control box and scribbling a few notes on how I did it a few years ago

[frijoli]

I wish I had thought of it before I populated the panel. lol

I don't have any room to spare....

[martyscncgarage]

Normally equipment I work with has an "on" circuit. Meaning even though everything is powered up, you can't start it until you push the on button, then you have to press start as well.
That way if you have a loss of main power it won't restart automatically when the power comes back on.

Should I add a latching circuit or is the reset in Acorn sufficient to do this from a safety standpoint?


Clay

My .02 y.m.m.v.

Magnetic contactors are generally a good safety feature for industrial controls. A CNC machine better not start running when power is restored to it....(as in the case of a manual machine).

If the way Centroid designed it works well for the industrial controls, then that's the way I roll. Estop relay can open the circuits of critical systems or systems that you want shut down in the event of a fault or Estop condition. You can go look at the All in One DC schematics to get an idea.
Look at relay CNT1:
http://www.centroidcnc.com/downloads/al ... ic_set.zip
You should use a quencharc suppressor across the coils of the relays.

Marty