Hello Guest it is September 20, 2019, 10:56:37 AM

Author Topic: My retrofit nightmare  (Read 20575 times)

0 Members and 1 Guest are viewing this topic.

Offline mvoros

*
  •  141 141
    • View Profile
Re: My retrofit nightmare
« Reply #20 on: May 11, 2013, 06:59:35 AM »
Hi rcaffin,
I thought the purpose of the the e-stop is to cut off all power in an emergency. I'm afraid you have me at a disadvantage, you see i"m not an electronics engineer, just an fitter and turner. Have no clue what those abbreviated words mean.  The machine came to me as a whole CNC already wired up and working. All I'm trying to do is to convert it from USB to ESS. But please explain what will happen to the ESS if I hit the e-stop. Will it damage it (the ESS)?
Mike

Offline Hood

*
  •  25,850 25,850
  • Carnoustie, Scotland
    • View Profile
Re: My retrofit nightmare
« Reply #21 on: May 11, 2013, 08:15:37 AM »
The purpose of the E-Stop is to stop your machine as quick as possible in as safe condition.
This can mean many things and involve many different methods depending on the machine itself.
For example removing the enables from a drive on a machine with friction on the axis will stop it very quickly, doing the same on a machine that has little friction (profile rails etc) can make it travel for quite a distance after the enable has been removed. Then of course there are axes that have gravity affecting them, that requires a brake on the axis so that when holding of the motor is removed it does not fall uncontrollably.

Also and E-Stop should ideally be multi layered, at its simplest is removing the power from the drives (by whatever means) and also informing the control (Mach) of an E-Stop situation so that Mach will halt the motion. A lot of people rely solely on the control issuing the E-Stop, this is not a god idea as if something goes wrong with the software then it will not stop, that is why a multi layered approach is best.

Also you do not really want to remove power (in most situations) from the control in an E-Stop, ie you want to keep Mach (and the ESS) ALIVE.

With your setup a simple approach could be to have a dual pole E-Stop, one NC one NO. The NC contacts would go to Mach via the E-Stop input and the NO contacts would connect to your drives enable signals. So what would happen in an E-Stop is the drives would get a signal on their Enable inputs which would disable them and at the same time Mach would get a signal on its E-Stop input and would halt motion. That is the minimum seup I would go for in your situation with your hardware.

Hood

Offline mvoros

*
  •  141 141
    • View Profile
Re: My retrofit nightmare
« Reply #22 on: May 11, 2013, 10:02:56 AM »
Hi Hood,
Thank you, that is a good explanation. I'm attaching photo of the what the switches look like from inside. I think they are the kind that you say they should be, but you be the judge. On my previous router (a US factory made one) I had the situation, that when I hit the e-stop the axis kept on going because the power was not cut off the BOB., remedied that by changing the e-stop with a dual one. The drawing that Arturo sent me, cuts off all the power from the machine, but by doing that will Mach also stop? I'm measuring 121 volt on the e-stop as well as on the main switch too. This is strange, because the main power to the machine is 220 volt.
Mike
« Last Edit: May 11, 2013, 10:04:59 AM by mvoros »

Offline Hood

*
  •  25,850 25,850
  • Carnoustie, Scotland
    • View Profile
Re: My retrofit nightmare
« Reply #23 on: May 11, 2013, 11:28:36 AM »
Would really need to see the other side to see what they are exactly. Even if they are E-Stops they shouldnt really be cutting the mains to everything.
You can have an E-Stop cut mains to drives in some situations, I do on some of my machines but not solely and really the E-Stop switch itself shouldnt do the mains switching, there sould really be an E-Stop string of a lower voltage which may disable a contactor that has the mains on it.


Regarding the 120v, that could be your location, if in the UK the mains are 240v per phase so your single phase mains consist of a live and a neutral. In the USA I think the 220v mains consists of two live lines of 110v each. If yo are in the USA then that will be why you are only getting 110v on the switch as there will just be one live and you will be measuring between it and a neutral or Earth.

Hood

Offline mvoros

*
  •  141 141
    • View Profile
Re: My retrofit nightmare
« Reply #24 on: May 11, 2013, 03:34:12 PM »
Hood,
They built it as 220 single phase. They sent me a  step up transformer from our 110 volt single phase to their 220.
Mike

Offline Hood

*
  •  25,850 25,850
  • Carnoustie, Scotland
    • View Profile
Re: My retrofit nightmare
« Reply #25 on: May 11, 2013, 04:18:04 PM »
Where does the transformer connect into things? Is it external to the machine or is it internal?
Hood

Offline mvoros

*
  •  141 141
    • View Profile
Re: My retrofit nightmare
« Reply #26 on: May 11, 2013, 05:35:19 PM »
It is external. from the wall outlet to the machine's electrical cabinet.

Offline rcaffin

*
  •  1,003 1,003
    • View Profile
Re: My retrofit nightmare
« Reply #27 on: May 11, 2013, 06:00:44 PM »
Quote
I thought the purpose of the the e-stop is to cut off all power in an emergency.
Hood is right: you want the eStop to remove power from the motors so they do no harm.

Quote
what will happen to the ESS if I hit the e-stop.
The ESS will lose all its programming and it's connection to the computer, and you will have to (basically) stop and restart Mach before you can get the machine to do anything useful.

Cheers

Offline Hood

*
  •  25,850 25,850
  • Carnoustie, Scotland
    • View Profile
Re: My retrofit nightmare
« Reply #28 on: May 11, 2013, 06:29:25 PM »
So if you measure the output of the transformer what is it?
Is the transformer output two live wires or a live and neutral?
Hood

Offline mvoros

*
  •  141 141
    • View Profile
Re: My retrofit nightmare
« Reply #29 on: May 12, 2013, 07:21:04 AM »
The transformers  output voltage is 220. It has two wires, 1 live (220) and one neutral.
Mike