Gallery, Projects and General > How to's

Installing a VFD

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PekkaNF:
Very good! I had no problem with the original test.

Now the interesting part: How would you connect chuck guards or other interlocking guard? How about E-stop.

I know what EU regulation says about real production machines, but it get's complicated. Principle would be that E-stop tells VFD to brake and a safety timer will turn out the VFD feed after a propriate delay time from the E-stop signal. In real life it gets a bit more complicated.

Best compromise I now is to put interlocking guards in series with enable/inhibit or stop signal (if it is active LOW) of the VFD.

E-stop I would like to kill all...I.E. cut voltage off from the spindle VFD, but it is not the fastest way to stop the spindle. This needs a little consideration and probably varies a lot depending of the application. Normal E-stop buttons don't handle full current of the bigger equipment, they need to be connected to a contactor.

Pekka

mexican jon:
Guard interlock is relatively easy as this can be tied into the stop or drive enable circuit, setting the deceleration time to suit  :thumbup: E-stops are an interesting thing  :scratch: In reality an E-stop shouldn't take into consideration the effect it may have on the machine (provided it doesn't make the machine dangerous) by that I mean when an E-stop is used in it's correct function it is to safe guard people and therefore doesn't worry about any damage or detrimental effect on the machine. As per their name Emergency Stop compared to a controlled stop which is the normal.

Pete.:
I wire the estop in series with the door/guard interlocks. Also in line with the stop button. That way if you hit stop, estop or open a cover the spindle is braked to a stop.

awemawson:
ESTOP should drop power to the servos / steppers & motors so you are not relying on electronics to stop things. On my CNC Plasma table for instance there are two poles on the ESTOP switch. One tells the electronics to stop everything, but the other drops out a relay in series with the stepper power supply

mexican jon:
Here's an Emergency stop system in its true meaning.

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