Enable pins on Stepper driver, are they required?

[Neale]

I've found a reference to e-stop in the HY VFD manual - it seems that it's possible to define one of the digital input pins to accept an e-stop signal. I need to go through the manual in more detail to find out which of the many parameters will control things like e-stop ramp-down time, or if it just chops output and uses DC braking. I also assume (I'm doing a lot of assuming at the moment) that it will need an external braking resistor to give best results. More research...

My current e-stop switches are built from modular components and are single pole at the moment but could easily have a second pole added, wired either as an independent mechanism or via the second channel of the safety relay. But again, I have to come back to the appropriate level of protection. But then, I'm the guy who removed the chuck guard from his vertical mill as the first action after installing. Instead, I bear in mind that it would be an error to insert finger into revolving cutter.

This thread has drifted some way from the original question about enable pins on drivers, but I don't think that there has been a definitive answer to that one yet...

[cropwell]

Instead, I bear in mind that it would be an error to insert finger into revolving cutter....

Been there, done that, lost a fingernail (but it has regrown, albeit lumpy). This is why I asked about braking resistors, as my little trip to the world of pain was taken while the cutter was on run-down.

Cheers,

Rob

[Neale]

This is why I asked about braking resistors

I've done a bit of googling of HY VFDs and braking resistors and there doesn't seem to be much folk wisdom out there. Plenty on how to make it spin up but very little on how to stop it again. The standard HY stop mechanism (if you just remove "run" signal) is to run down from current frequency to some pre-defined stop frequency at a rate given by a specified parameter, and then either coast to a stop or use "DC braking" according to another parameter. I can't find any specific description of how emergency braking works, but I haven't been through the manual word by word yet. I would have expected "cut power to motor and use DC braking", but in any case it sounds like there is a need for an external braking resistor. The manual does give recommended values for this, and it looks as if they are available from eBay or AliExpress for £20 or so.

[Clive S]

Been there, done that, lost a fingernail (but it has regrown, albeit lumpy). This is why I asked about braking resistors, as my little trip to the world of pain was taken while the cutter was on run-down.

Cheers,

Rob

Rob you should see this then https://www.youtube.com/watch?v=eiYoBbEZwlk they are made commercially they wreck the saw though I think there are types that clamp the blade with an explosive charge like a air bag.

[Neale]

My lathe has an electro-magnetic brake. I was worried that it might not work with the VFD I use to generate three-phase power but it actually works very well and brings a heavy chuck to a halt from 2K rpm in a surprisingly short time. Don't think I'll bother with trying to fit one to my 24K rpm spindle, though...