#31
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Quote:
Hi Nils, An AC motor has an inrush starting amps. a contactor is designed to allow for this. It is usually about 5 times the amps of the running motor. You have probably seen a little brown out from lights when you turn on a motor. Personally, I only ever use one contractor per motor. I think this is especially true when the motors have different functions. Since you can turn on the vacuum by G-Code, or the spindle, or the dust collector or the [ fill in your thing ] each thing should have it's own contactor. If you use a contractor as the mains, then it serves a whole different purpose. If that is the case, then a larger one allows for expansion. Dave |
#32
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Dave has good advice.
I have 2 independent contactors to turn on my Dust Collection and Router from the PMDX dry contact relay. This allows for current separation and the ability to change the "motor" contactor should my requirements for router and/or dust collector change. I have These (CN-22-F6 TECO IEC Contactor - 22A, 120VAC / 60Hz Coil, 3 Pole 600V, 1 N.O. / 1 N.C. Aux) as my e-stop/cabinet control and router control. Refer to my small schematic in my thread for details if your interested. Sean |
#33
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Nils,
You've brought up some interesting questions. IEC stands for Internation Electrotechnical Commission. CSA stands for Canadian Standards Association. CNS seems to stand for Chinese National Standards of Chinese Taipei. You'll need to ask an electrical contractor for a definitive answer on contactors and disconnect switches, but my understanding is that a disconnect switch must be rated to handle the full load that is pulled through the switch. A contactor must be rated to handle the full load of anything attached to it. The good news is that a 40A contactor is only slightly more expensive than a 22A contactor (at least at my local electrical supply house). Because you're based in the United States, you might have a way around the problem. All HOT conductors MUST be switched, but NEUTRAL conductors CAN be switched (as long as they are switched at the same time and by the same mechanism that switches their associated hot conductors). So a typical three-pole double-throw contactor could be used to switch three separate 120VAC lines or one 120VAC line and one 240VAC line. Your electrical contractor will have to be consulted to tell you how to do that. Personally, I would run only the stepper motors and the router/spindle directly through the control box. All auxiliary equipment would be run via mechanical relays or solid-state-relays from circuits outside the control box. The only connections that I could have going between the control box and any auxiliary device would be power to control the coil of a mechanical relay or the control voltage to control the SSR. |
#34
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Sean, Thanks for the input and I look forward to you getting yours done so I can take a look at it. I couldn't tell from you PDF on your controller what size contactor you used.
Dave, I like the idea of having different contactor for each tool or accessory. I didn't realize G-Code could turn things on. I haven't started looking at the running part. I am just starting to understand what I need to build one. I hope that since I was a software engineer that the g code will be the easy stuff. |
#35
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The contactor we are talking of here has one primary function - to turn things OFF when an E-Stop button is pushed. I think folk are missing the intent of this particular contactor:
- We need to have a couple of E-stop buttons spread over a large machine. - We cannot run heavy current in series through the machine and have the E-stops as disconnectors, so we use a central contactor and remote buttons to open the contactor. - Something drastic can go wrong and the contactor might not open when it has to - then we have the rotary disconnect switch on the door of the control panel. - This contactor will be more reliable as an emergency breaker if it never switches heavy currents. As we have it, it only switches on the Gecko's power supply, the small fan and the VFD (if applicable) which is not under load when energised. |
#36
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Gerald,
Understood, main e-stop contactor. Sorry for the divergent thread. What I forgot to mention is I actually bought the same (larger size) for all the contactors for easy of mobility should one fail. Sean |
#37
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Quote:
Using the PMDX to switch relays (mechanical or solid state) or contactors, under G-code, is discussed in at least this thread. |
#38
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Gerald,
Thanks. I am following the drawing and I was planning to purchase a SSR. Thanks for clearing this up. |
#39
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I have recently gotten nervous of SSR's - see the thread I linked to above. I like contactors, but the PMDX-122's outputs can't all drive contactors. They can drive small SSR's which should be okay to drive contactors.
(Contactors are good for single-phase and 3-phase - SSR's should be strictly used in 120V circuits only. Don't use where you have this dual 110-0-110V "split phase" or 3-phase) |
#40
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Mains power wiring
Well it's been a short while and with many weeks later, endless emails with certain individuals and the pocket burning a new hole, I have almost completed my 3 axis (4 motor) gecko based cnc controller. Let me first thank Gerald, what you've provided can never be thanked enough. I appreciate the community you have created and the help you have provided me especially. Also thanks to JR and Sean. Sean has helped me in ways I can't describe, and my controller is pretty much the same thing as his, a mask of sorts. I'm no wiring pro, don't claim to be and I'm pretty much a hack; electronics aren't my thing but I've learned a lot from all of you. Most of all, to be clean and organized so the flow of the cable, wires and components makes sense and are easy to understand and check.
With that said, here is where I'm stuck. The last part of this controller revolves around the power coming in from the ac inlet case mounted (done) to the rotary disconnect, then to the relay contactor onto the case buttons wired and then to the power supply. Everything else is complete (in the photos you won't see resistors on the geckos, didn't have them in at that time). After the wiring is set I will punch a few holes in the front for buttons, just left that for last in case I have to move the relay/rotary down to the left or right to accommodate for wiring. For the wiring setup I referred to Sean’s controller but as mine is simple, (no relay for spindle or power for spindle/or even dust collector) just a simple ac in to feed PSU and fan (then to geckos pmdx etc motors) I referred to Gerald’s original wiring diagram (as a guide) to run the power I needed. I went with a single phase (it’s a regular 110/120v residential line). As you see in Gerald's.. L1 goes into rotary, for me its (2) T1. N goes into rotary, (4) T2 G goes to plate (eventually ground pole added when it comes) Out of L1 it first gets split to the estop and on/off circuit (that part is fine with me, easy), then after the split goes to the contactor relay. L1 rotary goes to T1 (2) relay L2 (N) rotary splits to A2 at on lamp circuit to A1.. Also splits ..L2 (N) rotary goes to T2 (4) relay Out of the contactor relay in the same fashion out the top of it ending up going to the rest and PSU (the rest is cake again because no SSR, router spindle, just a fan and psu at dinnectors) Is it that simple or am I lost? I feel like it is easier than I'm making it or I'm forgetting a lot. But that's the way I read the contactor relay. In/out, electronic magnet with power creates the connection between T and L. Thanks again for all help and future help. Sean, Gerald, couldn’t have done it without you guys! And photos, thoughts/suggestions welcome! Still not done so a few loose wires here and there. |
#41
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Brian, have you looked at drawing 10 70 115 C ?
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#42
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Gerald, that's the drawing I'm referring to in my questions/post. Sorry if I was unclear about it.
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#43
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I don't think I get your questions then. Does this help?:
Took that drawing and deleted the stuff that is surplus for you. Can you give links to the data sheets of your rotary switch and contactor? I can guess which they are, but it is dangerous to guess in this area. Some closer photos of the switch and contactor side-by-side would also be useful. I could try and sketch in the wires on the photo. |
#44
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Thanks Gerald, I drew this up very quickly a little while back. The documentation on the rotary was brief to say the least, just how to assemble it, worthless since any random person could do that. No real "schematic". The relay contactor has a brief one as well, I attached the appropriate files. Thanks Gerald.
My questions stem around the contactor, and rotary. Power comes into rotary, then to estops on/offbutton and contactor, I listed how I believe they should be wired above but was just confirming before I did so. I'm pretty sure I'm right but it's a lot of power better to get a second opinion. I just wanted to know if I can assume your drawing (appreciate you posting a revised one minus a few things I'm not dealing with right now) is how I listed mine above. If you need I will draft it in autocad so you can see clearly where I believe things should go between AC IN and those components. |
#45
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I would do it this way, but I am not an electrician: Two rules are being followed: - Components are clipped to rail with writing up straight (not upside down) - Components are fed from the top. From L to T. |
#46
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Gerald, thanks you have definitely cleared a few things up with my end. Appreciate you taking the time to do so. The rest should be pretty easy, following your single phase drawing.
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#47
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Gerald, when you say lamp is that the lamp on for the on off buttons?
What is the coil? |
#48
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Mark, read those descriptions against the diagram shown in post #4 of this thread.
The "lamp" is on the front of the control box door. The coil is the part of the contactor. (solenoid) |
#49
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Gerald, I'm pretty much getting there, about to harness up and wire the final wires to the buttons on the door. Only part that has me a bit confused is what this is on the contactor.. I circled it so you can see. Is that just any other terminal on the relay contactor or something special? The coil is obvious, my contactor schematic highlights it but doesnt for this one. I'm assuming its just the next terminal I haven't used yet (again going from L to T as always). Thanks appreciate the help.
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#50
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Brian that is an auxiliary set of contacts. which normally has a much lower current rating than the main L ---> T contacts. I can see a pair on your photo marked 21 / 22, but that is a NC pair (Normally Closed). You are looking for NO (Normally Open Pair) and they seem to be just below the 21/22 pair?
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#51
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Gerald, sweet news. I fired it up after finishing. I will neaten up the wires a bit on the door later (as soon as I knew they would even work.) Even to my lack of confidence it turned out that it was as simple as your drawing showed. It powered up, through the rotary disconnect. The "on" button turned on the magnetic relay (it clicked!) and the lamp is illuminated. Power to the PMDX board is hot, as it is apparent through the green led(s). However my geckos and heatsink fan under them are not. My wires on my fans aren't marked or colored so it was a 50/50 shot at which would be? Maybe doesn't matter polarity wise. Will try switching those now. Any tips/advice on using a multimeter to check receiving power? Things to be careful with? I bought a good digital one, my only hopes are that I don't zap myself and that's about it. I will imagine that I can narrow down the problem pretty easy but any advice is appreciated. Thanks for all the help so far, almost there Gerald! Photo to come.
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