DIY - Choosing MCBs and magnetic contactors, etc. - need advice


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Thread: DIY - Choosing MCBs and magnetic contactors, etc. - need advice

  1. #1

    Default DIY - Choosing MCBs and magnetic contactors, etc. - need advice

    I'm in the process of building a DIY CNC machine for woodworking, ( Another DIY CNC Machine Project), And I am needing to make some decisions and purchases of various electronic parts for the controller. My experience is limited so I have some questions for the CNC Electronics hive mind I hope I can get. some advice on. This particular machine will have a 3.5KW Air Cooled spindle that comes with a 220 single phase 4KW Huanyang VFD HY04D023B that is rated at current draw of 18 Amps. It will also have 4 Delta ASD-B3-0421-L 400W 220V AC Servo Motor Drives with 4 ECM-B3M-20604RS1 400W 220V AC Servo Motor. The controller board will be a UC300ETH-Max, (UC300ETH with UB!/UD1 BOB and UCCNC). There will be one MEAN WELL SDR-75-24 - 75 watt 24 volt DIN Rail Power Supply for the controller and I may have an additional 60 watt 12 volt Power supply for cooling fans.

    1.1 My assumption is my input power needs to be a single phase 30 Amp 240 circuit. My questions arise from how many branch circuits there should be in the controller box. I would think that there should be at least one 20 Amp MCB for the HY VFD and possibly one 10 Amp for the Servo Drives and DC power supplies, but would it be better to have a separate 1 Amp MCB for the DC power supplies?
    1.2 Should the Mini Circuit Breakers be UL 489 or UL 1077?
    1.3 What Trip Curve should the MCBs be. B, C or D? Should I assume D because the HY VFD and and Servo Drives are motors?
    .
    2.1 My second area of questioning is how to choose magnetic contactors that I can use both to switch on power for each circuit as well as trip the power off from an alarm circuit.
    2.2 Also should I have a main cutoff switch for power that feeds the breakers, should it also be a magnetic contactor or would it be better to be something like this Merz rotary cutoff switch

    I'm sure the answers I get will probably elicit further question on integrating these parts together correctly including adding an EMI filter per my Delta manual and other issues you all might raise.

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  2. #2
    Community Moderator Jim Dawson's Avatar
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    Default Re: DIY - Choosing MCBs and magnetic contactors, etc. - need advice

    1.1) 30 amp circuit might be OK, 40 amp might be safer to prevent nuisance trips on startup. The Delta manual suggests a 10 amp breaker for the drives

    1.2, 1.3) I normally use one breaker for each drive and power supply input. UL 1077 breakers, C curve. So that would be four 10 amp and one 30 amp breaker for the drives, and one 5 amp for each power supply.

    2.1) One 10 amp contactor for each Delta drive, and at least one ice cube relay for the E-stop/control power circuit. Normally you would use contactors/relays with 24VDC coils.

    2.2) I normally use a rotary switch for the main panel disconnect, or use a seperate main disconnect on the wall.

    Handling the alarm shutdown could be done through another relay and as part of the E-stop circuit. I normally add a provision for a controller generated E-stop via an E-stop permissive relay. The controller is a lot faster than you are. But under no condition would you allow the controller to energize the control power, it only allows the control power to be energized by you pushing the control power button. In other words, if the controller is happy then you are allowed to energize the control power.

    Here is a 2 servo panel, 230V, single phase panel I built a few weeks ago for a non-CNC project. One breaker for each drive, one breaker for the 24V power supply input, one breaker for the 24VAC transformer input, one preaker for the 24VDC output, and one breaker for the 24VAC transformer output. In this case I had a need for 24VAC on the machine, normally would not be found on a CNC machine. There is no controller in this machine.

    DIY - Choosing MCBs and magnetic contactors, etc. - need advice-img_3472-jpg

    Here is the main power schematic

    DIY - Choosing MCBs and magnetic contactors, etc. - need advice-main-power-jpg

    Attached Thumbnails Attached Thumbnails DIY - Choosing MCBs and magnetic contactors, etc. - need advice-img_3472-jpg   DIY - Choosing MCBs and magnetic contactors, etc. - need advice-main-power-jpg  
    Jim Dawson
    Sandy, Oregon, USA


  3. #3

    Default Re: DIY - Choosing MCBs and magnetic contactors, etc. - need advice

    Quote Originally Posted by Jim Dawson View Post
    1.1) 30 amp circuit might be OK, 40 amp might be safer to prevent nuisance trips on startup. The Delta manual suggests a 10 amp breaker for the drives

    1.2, 1.3) I normally use one breaker for each drive and power supply input. UL 1077 breakers, C curve. So that would be four 10 amp and one 30 amp breaker for the drives, and one 5 amp for each power supply.

    2.1) One 10 amp contactor for each Delta drive, and at least one ice cube relay for the E-stop/control power circuit. Normally you would use contactors/relays with 24VDC coils.

    2.2) I normally use a rotary switch for the main panel disconnect, or use a seperate main disconnect on the wall.

    Handling the alarm shutdown could be done through another relay and as part of the E-stop circuit. I normally add a provision for a controller generated E-stop via an E-stop permissive relay. The controller is a lot faster than you are. But under no condition would you allow the controller to energize the control power, it only allows the control power to be energized by you pushing the control power button. In other words, if the controller is happy then you are allowed to energize the control power.

    Here is a 2 servo panel, 230V, single phase panel I built a few weeks ago for a non-CNC project. One breaker for each drive, one breaker for the 24V power supply input, one breaker for the 24VAC transformer input, one preaker for the 24VDC output, and one breaker for the 24VAC transformer output. In this case I had a need for 24VAC on the machine, normally would not be found on a CNC machine. There is no controller in this machine.



    Here is the main power schematic
    Hi Jim,

    Thanks for your Input. Are you recommending that I just change the 30Amp breaker out with a 40Amp breaker just to handle current inrush or should I also change the wiring from 10AWG to 8AWG?

    I would really appreciate it if you would divulge your source for breakers, contactors and switches as well as any model numbers you can provide. I would find that very helpful.

    --Tom



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    Community Moderator Jim Dawson's Avatar
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    Default Re: DIY - Choosing MCBs and magnetic contactors, etc. - need advice

    My pleasure

    If you use a 40 amp breaker, you are going to have to use #8 wire from the shop breaker panel to the machine. If you already have a 30 amp installed and have #10 wire to the machine, then I would try it as it is.

    Automation Direct is my prefered vendor. Everything in the panel above was purchased from Automation Direct. But I did buy the box from Amazon.

    https://www.automationdirect.com/adc/home/home

    https://www.automationdirect.com/adc...%20asc&start=0

    https://www.automationdirect.com/adc...%20asc&start=0

    https://www.automationdirect.com/adc..._ms=%223PDT%22

    https://www.automationdirect.com/adc...%20asc&start=0


    If you have any problems finding specific part numbers I'll be happy to help.

    Jim Dawson
    Sandy, Oregon, USA


  5. #5

    Default Re: DIY - Choosing MCBs and magnetic contactors, etc. - need advice

    Quote Originally Posted by Jim Dawson View Post
    My pleasure

    If you use a 40 amp breaker, you are going to have to use #8 wire from the shop breaker panel to the machine. If you already have a 30 amp installed and have #10 wire to the machine, then I would try it as it is.

    Automation Direct is my prefered vendor. Everything in the panel above was purchased from Automation Direct. But I did buy the box from Amazon.

    https://www.automationdirect.com/adc/home/home

    https://www.automationdirect.com/adc...%20asc&start=0

    https://www.automationdirect.com/adc...%20asc&start=0

    https://www.automationdirect.com/adc..._ms=%223PDT%22

    https://www.automationdirect.com/adc...%20asc&start=0


    If you have any problems finding specific part numbers I'll be happy to help.
    I have to rewire an existing 15Amp 240 Circuit so I'll be pulling #8 and replace the existing 15 Amp double pole breaker with a 40 Amp Breaker. I wasn't sure if you were suggesting the 40 Amp breaker on a 30 amp circuit just to prevent inrush nuisance trips. I had to do that on my 5HP dust collector. It is #8 on a 40 Amp Breaker but the DC has a #10 cord on a L630P and the #8 terminates at a L630R. The DC is rated at 28 Amps but will pull 30+ when the motor starts.

    I have been shopping around Automation Direct some already. It seems no matter where you shop though Eaton breakers are out of stock. I assume the Gladiator ones at Automation direct are decent quality? They certainly are cheaper.

    I have zero experience with magnetic contactors so I may need some help there if I can't figure out what I need.

    It's going to be a while before my spindle/VFD and Servo Motors arrive so I have some time to puzzle all this out and figure out how big of a box I'll need. I'm mostly trying to avoid making mistakes and purchase the right components, but I'm very much an electronics noob. I'll need all the help I can get.
    .



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    Default Re: DIY - Choosing MCBs and magnetic contactors, etc. - need advice

    Quote Originally Posted by TeeTomTerrific View Post

    I have been shopping around Automation Direct some already. It seems no matter where you shop though Eaton breakers are out of stock. I assume the Gladiator ones at Automation direct are decent quality? They certainly are cheaper.
    I think that's what I used in the panel above. At least they are from a reliable vendor. The ones you buy on eBay or Amazon I would not trust. Some of them are counterfeit, just a switch made to look like a breaker, very dangerous.

    Jim Dawson
    Sandy, Oregon, USA


  7. #7

    Default Re: DIY - Choosing MCBs and magnetic contactors, etc. - need advice

    Delta recommends in their manual an EMI filter between the contactor and the drive and specifically they recommend a Delta EMI filter with the one for my 400 Watt Drive being a model EMF023A21A. This is of course an unobtanium part in the US. The only place I have found it is a Chinese site yoycart.com and it is $77.85 for 1. Yikes!!!

    Originally Based on another recommendation I purchased a
    TDK-Lambda RSEN-2030LD 30 Amp EMI filter when I was working under the assumption I would be using 1 breaker and contactor for all 4 of my drives. My assumption now is I need 4 EMI filters but the TDK-Lambda RSEN-2010LD is out of stock everywhere I have checked. A similar model RSHN-2010LD is also out of stock except for 4 at mouser.com. Do you have any recommendations for an alternative or should I go ahead and spring for those 4 while I can since it may be months before there are any more available anywhere.



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    Community Moderator Jim Dawson's Avatar
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    Default Re: DIY - Choosing MCBs and magnetic contactors, etc. - need advice

    Take a look here
    https://www.automationdirect.com/adc...%20asc&start=0

    As a side note, I have not used EMI filters on my many installations and have had no problems.

    Jim Dawson
    Sandy, Oregon, USA


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    Community Moderator Al_The_Man's Avatar
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    Default Re: DIY - Choosing MCBs and magnetic contactors, etc. - need advice

    I also recommend going with 24vdc for all control wiring, including all contactor coils also to be 24vdc rated, this fits in well with LED indicators etc, and LV.
    E-Stop control circuitry. etc.
    .

    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
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    Quote Originally Posted by Al_The_Man View Post
    I also recommend going with 24vdc for all control wiring, including all contactor coils also to be 24vdc rated, this fits in well with LED indicators etc, and LV.
    E-Stop control circuitry. etc.
    .

    I'm looking into the same thing. I'm full 24v control circuit but live in the UK.
    24vdc coil contactor are non existent or 4 times the price.
    Mainly 24AC or 220AC all that's available.

    Looking like the cheapest way for me is to use a 24vdc coil ice cube relay to control a 220AC contactor.

    A relay to control a relay, the UK is total bollocks for getting the kit you want.



  11. #11

    Default Re: DIY - Choosing MCBs and magnetic contactors, etc. - need advice

    Quote Originally Posted by dazp1976 View Post
    I'm looking into the same thing. I'm full 24v control circuit but live in the UK.
    24vdc coil contactor are non existent or 4 times the price.
    Mainly 24AC or 220AC all that's available.

    Looking like the cheapest way for me is to use a 24vdc coil ice cube relay to control a 220AC contactor.

    A relay to control a relay, the UK is total bollocks for getting the kit you want.
    Have you tried a company called Lamonde? https://www.lamonde.com/cwc012-10-30l03.html



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    Quote Originally Posted by TeeTomTerrific View Post
    Have you tried a company called Lamonde? https://www.lamonde.com/cwc012-10-30l03.html

    I'll check it out once I get to a laptop.
    I need something for a 2kw 30A rated servo on single phase.



  13. #13

    Default Re: DIY - Choosing MCBs and magnetic contactors, etc. - need advice

    Quote Originally Posted by dazp1976 View Post
    I'll check it out once I get to a laptop.
    I need something for a 2kw 30A rated servo on single phase.
    Take a look at this one. https://www.lamonde.com/cwb32-11-30c03.html



  14. #14

    Default Re: DIY - Choosing MCBs and magnetic contactors, etc. - need advice

    I have been trying to better educate myself about contactors though shopping, reading specs and a few YouTube videos. The videos I've watched generally have the coil voltage the same as the load voltage and not 24VDC. I assume the power for the 24VDC comes from the same power supply that powers my controller, but I'm not sure if either of these two miniature contactors, CWC012-10-30L03 or CWC012-01-30L03 work the same as what I've seen demonstrated. I also am not exactly sure what is meant by an auxiliary contact. I assume it allows for an additional input like from the controller board or an E-Stop or both to power on or off the switch coil. I'm not sure if this miniature contactor needs a momentary switch or a latching on/off switch and the docs are just not clear about that. These two are both fairly inexpensive but currently out of stock at Automation direct, (but possibly may be found elsewhere). I did find a more expensive alternative CWB12-11-30C03 at Marshall Wolf Automation that has two auxiliary contacts 1 NO and 1 NC instead of having to choose 1 or the other type in the ones available from Automation direct.

    I'm hoping one of you can give me some clarity on these contactors. How to pick an appropriate switch to enable power on and power off from a panel, sending an E-Stop from the controller and or a hard wired E-Stop button plus how many auxiliary and what type contacts I really need. Also, assuming I can send an E-Stop for all the Servo Drive contactors at the same time, can I also power on all the drives with one button? Would I want to do that or should each drive be powered on separately?

    TIA

    --Tom



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    Quote Originally Posted by TeeTomTerrific View Post
    I have been trying to better educate myself about contactors though shopping, reading specs and a few YouTube videos. The videos I've watched generally have the coil voltage the same as the load voltage and not 24VDC. I assume the power for the 24VDC comes from the same power supply that powers my controller, but I'm not sure if either of these two miniature contactors, CWC012-10-30L03 or CWC012-01-30L03 work the same as what I've seen demonstrated. I also am not exactly sure what is meant by an auxiliary contact. I assume it allows for an additional input like from the controller board or an E-Stop or both to power on or off the switch coil.
    --Tom

    I'm daisy chaining my NC E-stop circuit in series.
    Starts at +24vdc into breakout board input + side opto then> -side opto out (GND sinking line) through cont coil A1/A2> through any shutdown relays +in -out>
    Through any controller fault relays com/nc or no depending on high or low>
    Through npn NC limit sensors sig,in -out
    Sink into GND.

    Hitting E-stop will/should switch off cont /relays and trigger bob input shutting down everything together.

    Sensor trigger will activate E-stop.
    Control faults should do the same (ie: servo error).

    I'm taking a punt on.....
    https://www.aliexpress.com/item/1005004100221439.html?spm=a2g0o.order_list.0.0.187 51802OLQfJ5
    And a load of.......
    https://www.aliexpress.com/item/4001007647681.html?spm=a2g0o.order_list.0.0.187518 02OLQfJ5
    24v and 230v options in dif colours.
    They feel quality actually, good weight to them.
    They came today but MC is on back burner again.
    Will try and get a quick bench test in though.

    Last edited by dazp1976; 05-10-2022 at 07:18 PM.


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    Community Moderator Jim Dawson's Avatar
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    Default Re: DIY - Choosing MCBs and magnetic contactors, etc. - need advice

    Quote Originally Posted by TeeTomTerrific View Post
    I have been trying to better educate myself about contactors though shopping, reading specs and a few YouTube videos. The videos I've watched generally have the coil voltage the same as the load voltage and not 24VDC. I assume the power for the 24VDC comes from the same power supply that powers my controller, but I'm not sure if either of these two miniature contactors, CWC012-10-30L03 or CWC012-01-30L03 work the same as what I've seen demonstrated. I also am not exactly sure what is meant by an auxiliary contact. I assume it allows for an additional input like from the controller board or an E-Stop or both to power on or off the switch coil. I'm not sure if this miniature contactor needs a momentary switch or a latching on/off switch and the docs are just not clear about that. These two are both fairly inexpensive but currently out of stock at Automation direct, (but possibly may be found elsewhere). I did find a more expensive alternative CWB12-11-30C03 at Marshall Wolf Automation that has two auxiliary contacts 1 NO and 1 NC instead of having to choose 1 or the other type in the ones available from Automation direct.

    I'm hoping one of you can give me some clarity on these contactors. How to pick an appropriate switch to enable power on and power off from a panel, sending an E-Stop from the controller and or a hard wired E-Stop button plus how many auxiliary and what type contacts I really need. Also, assuming I can send an E-Stop for all the Servo Drive contactors at the same time, can I also power on all the drives with one button? Would I want to do that or should each drive be powered on separately?

    TIA

    --Tom

    A relay or contactor can be thought of as a remote controlled switch. You energize the coil and this electromagnetically closes the contacts, thus you can control multiple contacts with a single switch. The Aux contacts are normally used as a ''seal-in'' or self holding contact to keep the coil energized in the case of a momentary switch. There are other uses also. In your case, the seal-in would be accomplished by an external source, the E-stop/control power relay.

    Below is an example of the wiring using aux contacts for seal-in along with a momentary switch. But the power is supplied through the ESR1 relay, so if the E-stop button is pushed, the power is dropped to the contactors. This is the control circuit for the panel I posted above.

    NOTE: A relay and a contactor are electrically identical, but a relay becomes a contactor when used to switch high current loads like motors and drives, rather than control power loads like other relays and contactors. On drawings these are usually noted as CR = control relay, and C = contactor.

    DIY - Choosing MCBs and magnetic contactors, etc. - need advice-e-stop-servo-contactors-jpg

    Attached Thumbnails Attached Thumbnails DIY - Choosing MCBs and magnetic contactors, etc. - need advice-e-stop-servo-contactors-jpg  
    Jim Dawson
    Sandy, Oregon, USA


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    Default Re: DIY - Choosing MCBs and magnetic contactors, etc. - need advice

    Any reason why you guys are determined to use 24v control power? You are already using higher voltages for other portions of your circuits. So safety is moot unless you do a poor job.

    Not dishing on anyone or chest puffing. Just my own experience I used 110 sometimes 230. Lots of cheaper contactors avaiable because its the common industry standard. Well here anyways. No need to use the fake ebay ones ive seen some of them. Spares in stock at the shop down the road. Easy and done.

    My two cents. Is proper earth earth earth.

    Sent from my SM-N970F using Tapatalk



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    Quote Originally Posted by boydage View Post
    Any reason why you guys are determined to use 24v control power? You are already using higher voltages for other portions of your circuits. So safety is moot unless you do a poor job.

    Not dishing on anyone or chest puffing. Just my own experience I used 110 sometimes 230. Lots of cheaper contactors avaiable because its the common industry standard. Well here anyways. No need to use the fake ebay ones ive seen some of them. Spares in stock at the shop down the road. Easy and done.

    My two cents. Is proper earth earth earth.

    Sent from my SM-N970F using Tapatalk

    If the controller is 24v wouldn't you need an ice cube power relay for it to control the 230v contactor coil?. That's yet another relay.
    For hobby/garage use machine it just seems easier to have a direct 24v instead of even more components that could fail.

    On a normal day you'd have it all on a safety relay but at $250+, no thanks.



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    Community Moderator Jim Dawson's Avatar
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    Default Re: DIY - Choosing MCBs and magnetic contactors, etc. - need advice

    Quote Originally Posted by boydage View Post
    Any reason why you guys are determined to use 24v control power? You are already using higher voltages for other portions of your circuits. So safety is moot unless you do a poor job.

    Not dishing on anyone or chest puffing. Just my own experience I used 110 sometimes 230. Lots of cheaper contactors avaiable because its the common industry standard. Well here anyways. No need to use the fake ebay ones ive seen some of them. Spares in stock at the shop down the road. Easy and done.

    My two cents. Is proper earth earth earth.

    Sent from my SM-N970F using Tapatalk
    120VAC pilot devices are acceptable per NEC. 230V and 460V are acceptable for some very special use cases that we as hobbyists do not run into often. In this case Tom already has 24VDC power on the machine, but no 120VAC. Most modern CNC equipment uses 24VDC control power.

    Jim Dawson
    Sandy, Oregon, USA


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    Default Re: DIY - Choosing MCBs and magnetic contactors, etc. - need advice

    All good stuff. I guess I was just saying, a control transformer is all that would be needed to then increase the availability and lower the cost of the build. Personally for me, Diy is about using what we can. Spend as little as possible. Use hours and hours of our time up making something ourselves instead of buying it for $100. That kind of stuff.



    Sent from my SM-N970F using Tapatalk



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DIY - Choosing MCBs and magnetic contactors, etc. - need advice

DIY - Choosing MCBs and magnetic contactors, etc. - need advice

DIY - Choosing MCBs and magnetic contactors, etc. - need advice