#151
|
|||
|
|||
The leftmost two wires in my diagram need to be swapped. The very left wire is the common for all the pushbuttons, ie. ground. But, if you trace it up to the PMDX, it goes to the dedicated e-stop input.
|
#152
|
|||
|
|||
Thanks for your help Gerald,
The mains e-stop is only 12v dc. Will that cause problems with the 5v circuits having it in the same cable? I could eliminate one of the prox sensors (don't think the z is that important) and run it in that cable. Good catch on the e-stop / common swap. It was the last thing I finished up at 1am before I submitted the pic. I'll make that change. Brad, The transformer is only powered when the mains switch is turned on. It can't be powered by the contactor because it's powers a "NO" relay that the ON/OFF circuit goes through. Kind of a catch 22 - can't turn the power on until the relay is energized but can't energize the relay until the power is turned on. That's why I powered it after the mains switch so it can still be turned off. |
#153
|
|||
|
|||
Quote:
That will not cause any problems. AC signals are the ones that radiate a lot of noise. The shielding on the dc signals is only to keep the ac noise out. Shielding on the ac lines help keep their noise in. |
#154
|
|||
|
|||
Greg, my reading of your diagram is that the estop transformer is NOT part of the "start drives" circuit, and thus could be powered by the contactor, since the contactor is triggered by the start drives circuit, thus energizing the estop transformer as well as the rest of the "stop drives" circuit. No catch-22 ;-)
|
#155
|
|||
|
|||
Sorry Greg, I didn't look at the 12V stuff. Yes, 12VDC in that cable will be okay.
|
#156
|
|||
|
|||
Brad,
Sometimes one can't see the forrest through the trees. I went back and looked at the drawing and told myself he must be crazy....and as I repeated your words while running my finger over the diagram it hit me. Thanks...... Heath, I'm wondering if the second e-stop circuit should be in a different cable anyway. I'm probably waaaaay over thinking this one but suppose the hv e-stop ground were to short to the lv e-stop + very early in the cable (before any of the buttons). As far as the pmdx were concerned everything would be okay. But when you hit a stop button nothing would happen. |
#157
|
|||
|
|||
You're quite welcome, Greg. It's a pet peeve of mine; I like knowing that when I hear that 'clunk' of the main contactor cutting out, there is no power at all left anywhere in the machine. (Related issue: providing bleed resistors for anything with big capacitors, though on a Mechmate, as Gerald points out, those resistors are called Gecko Drives).
|
#158
|
|||
|
|||
If I understand this right, you are relying on a miniaturised 12VDC coil relay to open 120VAC contacts when you push an e-stop? I don't know if this is standard practice - I would check that relay out carefully to convince myself it is as reliable as a contactor. A contactor has a tough spring to open the contacts and a big coil to close them. That's what makes the satisfying "clunk"
|
#159
|
|||
|
|||
Sounds kind of crazy doesn't it.
I tried looking up the coil draw on my contactor the Teco CN-16-F6 and can't seem to figure it out. |
#160
|
|||
|
|||
Watching closely Greg,
This point of the project is "sleepless nights". Let me re-state that "FUN sleepless nights". If it wasn't fun, we wouldn't be doing it. Your almost cutting. |
#161
|
|||
|
|||
Greg,
Per your post: Quote:
http://factorymation.info/motor_cont...N-9toCN-16.pdf Looks like the energized power consumption is 12 VA. I don't know what "SEALED" means. To get to the specification, click on CN-16-F6 on this page: http://74.125.95.132/search?q=cache:...lnk&cd=1&gl=us Regards, John |
#162
|
|||
|
|||
Hi Greg,
I can understand what you're talking about. The anticipation is killing me. It's really painful waiting for parts (that should have been ordered sooner) to be delivered. I'm also trying to figure out how Gerald knew about the lawn ornaments. |
#163
|
|||
|
|||
Thanks John,
Don't know how I missed that... Looks like around 6 or so amps. That's good to know. The relay I was going to use can only handle 6 amps. That's not enough head room for me. I may go with a contactor like Gerald recommends, or an auto relay like J.R. uses. Just happen to have one of those on hand. |
#164
|
|||
|
|||
12VA consumed off a 120V circuit means only 0.1 Amp (Volts X Amps = VA)
Inrush 70VA is the figure I would design for. Also make sure your relay's contacts open wide (and fast) enough to handle 120V. |
#165
|
|||
|
|||
I thought amps were RMS volts (volts *.707) / VA?
It makes sense that it should be able to handle the inrush current however it shouldn't ever see that. The start drives button should take that load then once released pass the hold current through the stop drives circuit. |
#166
|
|||
|
|||
VA is definitely Volts X Amps, equivalent to Watts.
Eg. think of a 500 VA power supply giving 10 Amp @ 50 Volt |
#167
|
|||
|
|||
Greg,
Okay, I think I've finally spent enough time with your Control Box wiring layout to understand what you're doing. First, as usual, Gerald is right. The INRUSH "current" at 120 volts would be 70 VA divided by 120 volts or about .6 Amps, i.e. 600 milliamps. That's not much of a challenge for most relays with contacts rated to switch 120 volts AC. So assuming your 12 VDC coil relay has contacts rated for switching 120 volts AC, you should be fine...you already said the contacts are rated for 6 Amps. Second, I would like to revisit Brad's issue about leaving the 12V DC supply powered all the time per the following quote: Quote:
My plan is to turn on the 12 VDC power supply in parallel with the Contactor when the On Button (in your case Start Drives button) is depressed. It will be "latched" on by the same Contactor contact that latches the Contactor. Just a thought. Regards, John |
#168
|
|||
|
|||
HI John, I dont know if what Greg has done is right or wrong - but I have taken a similar approach.
I have a 24V DC power which is always on status when power is switched on to the controller. this powers the Estop, proximities, pause, start switches. a key switch is used in series with estop to activate the contactor. the reason behind using 24V is to have a common DC voltage powering all accessories wiithout trouble of facing a possible shock from the 220v supply. I will be powering the 24V transformer with a 500mA fuse in between which will take care of any shorts on the small transformer end. and also any failure of the transformer will auto trigerr an estop. ok wait I am I on topic, well still i will continue The different inputs have opto isolated inputs to the BOB. RGDS Irfan |
#169
|
|||
|
|||
Irfan,
I don't think there is a "right" or "wrong" on this point. I, along with, I am sure others, have become more aware of the "energy" cost of "always on" devices. So, the design I have been working on takes this into account. Have you wired your 24 volt supply to be powered through the Disconnect? If yes, do you plan to turn off the Disconnect between machine uses or do you plan to leave the Disconnect engaged and power on and off the table using the On Button and Off Button? BTW, Irfan, I have followed your progress with great interest. Thanks for sharing. Regards, John |
#170
|
|||
|
|||
If I understand correctly the disconnect is the contactor - I will be switching it on and off thru a relay powered by the 24V supply,
the whole set up is put on - off by the rotary on off switch. (in my case it is wall mounted) RGDS Irfan |
#171
|
|||
|
|||
The 12/2 ga shielded cable showed up today.
It's a milspec M27500-12 SD2T23. The down side.....Not very flexible.....the individual wires are about the same as 12ga stranded thhn. That's not the least of it. After cutting off the outer jacket I noticed that the shielding was very black. when I cut off the inner jacket of the individual wires it was the same. It looks either VERY old or as though it sat in water. There were 37 strands in each conductor. I'm glad I only paid .35/ft The 14/3 ga I received from Ebay is much more flexible. Each wire contains 40 strands. I went ahead and used the 14ga. It only has about 15ft or so to travel so I don't expect it to be a problem. |
#172
|
|||
|
|||
Greg,
Thanks for the update. I was wondering if you had received that MIL SPEC cable. Great pictures and analysis. Saved me from going down that same path. The 14 ga. from Ebay looks good. Regards, John |
#173
|
|||
|
|||
Greg,
Sorry for the problems with wire #1. From the look of the tarnishing, it looks like the wire was silver coated. This is probably why it tarnished to black. Dont use this wire! Not a good idea to use it at all in this condition. |
#174
|
|||
|
|||
Good news....Got things running tonight!
I still have a lot of work to do but I do have the motors turning and axis moving.. I had to make a few changes to the wiring. First I needed to run a separate neutral wire to the router indicator light and to the power on light. I had the power light inline with the contactor coil and it didn't like that, and the way the router light was wired would have been 220v. I also realized that there was no need for the second 12v transformer so I made changes to that wiring as well. The HV E-Stop works. I just need to test the LV E-Stop, pause and start butons. I also need to finish getting the prox sensors set up. Now for the bad news. I got called out of town and won't be able to work on the MM for at least a week. Here are some photos of my control box. I still have a little tidying up to do but for the most part it's finished. I will say that if I did it over again I would definately use a larger box. Cheers. |
#175
|
|||
|
|||
Well done Greg!
What are your control box dimensions? |
#176
|
|||
|
|||
Thanks Gerald,
The box is 20x16x8.....Inches that is. Granted my extremely oversized powersupply doesn't help the situation. I believe only 2 more inches height (width as viewed) would have made life much easier. Last edited by gmessler; Sun 14 December 2008 at 22:53.. Reason: missed something |
#177
|
|||
|
|||
Good going Greg, nice work. (cutting before Christmas?)
I agree with you on the box size, my hands are just too big to work comfortably on all those closly spaced components, I would also go for a bigger box just to make working inside it easier. |
#178
|
|||
|
|||
Greg,
Looking good! Hope everything else goes well for you. |
#179
|
|||
|
|||
Thanks Alan & Heath,
Back in town tonight. Can't wait to get back to work on the MM. If I went out to the garage tonight I think the wife would make me stay out there. Looks like tomorrow morning. Missed the "12" 14? |
#180
|
|||
|
|||
*starts dusting off the #14*
|
|
|