[accuartisans]

I'd like to get some input for my wiring circuit design for E-STOP, Power On and Servo Drive Enable for the retrofit of my 3-Axis Bed Mill. It originally had a Delta 20 controller which I am retrofitting with LinuxCNC utilizing Mesa 7I80DB Ethernet and 7I77 Analog Servo interface cards. Also, I have purchased BE25A20 AMC servo drives to replace the older 1525 drives. Have this all up and running in a mocked up layout and now the wiring fun begins!

I am fairly good with “automotive” electrical/electronics (even the old positive ground systems) but clearly a learning novice to “real” electronics. For example I am confused by term “DC common” as I only know of +(positive) and – (negative) and I think DC common equals negative? I do know what AC common/neutral is however.

The spindle motor is a 3hp 3-phase motor that I plan on driving with a VFD. Therefore I planned for the need of 2 30A 220 1-phase to drive my machine. One 30A circuit will drive 2 isolated transformers, one for 120VAC that will drive 5vdc and a 24vdc power supplies and the other at 72VAC that drives the Servo power supply and drives/motors. The second 30A circuit will drive the spindle VFD.

At a high level I will try and explain the wiring diagram logic below, at least how I think it should be working.

Power on sequence:
The main power switch will power up the 120v AC transformer and both 5vdc and 24vdc power supplies.
Pressing the momentary power on button will energize “RLY1”, energizes “RLY4” which energizes both RLY2 and RLY3 and provides a “Power On and E-STOP OK” input to the interface board.

Relay RLY2 energized powers up the 72vac isolated servo transformer which provides power for the servo drives.
Relay RLY3 energized powers up the the Spindle VFD.

There is 24vdc supplied to the limit switches were if all the limit switches are “OK” will then energize “RLY5” to enable/disable the servo drives.

Note: The existing limit switches are capable and wired in such a way I can get a signal for when any of the limit switches break and a separate signal for what extent (+ or -) of the specific axes limit switch broke. The nice thing about this feature is the old controller has an “override” button that allows the servo drive to re-enable to jog only that axes off the opposite direction. This is nice as otherwise it would be difficult to mechanically move the axes as they are closed. I would like to preserve this capability, which I have as inputs to the interface board. This would aslo enable the “override” functionality.

E-STOP sequence:
If the E-STOP button is pressed then that drops the energized RLY1, RLY4 to RLY2 and RLY3, this drops all the power to the Spindle and Servos.

Limit Switch sequence:
Breaking a limit switch drops the energized RLY5 and then disables the servo drives. Is this adequate?

I've attached my wiring diagram for comments, input, etc. I started this diagram in sections of concern and added to it as I went along, so the actual layout of wiring isn't how I would actually wire it from a clean point of view. Remember, I'm a novice so yo aren't going to hurt my feelings and the symbols may not be to a electronics standard, but it is what I came up with using “Inkscape”. Also, I have my “Power Center” build layout completed, pictures below.

Several questions:
1) Do I use the “hard wire” approach to enable the servo drives via the limit switches? Or can I use the limit switch input to the interface card and then have an output to the servo drive enable relay 4?
2) I am unsure where to source what I need utilize the AMC “inhibit” pin. Noted in my diagram as well as the text for the pin from the AMC data sheet.
3) Is this a fairly “safe” wiring diagram?

Also, I don't show it on my diagram, but I will have a “fly back” diode on all the DC relays. Do I need something on the “AC” relays? Is it still a “fly back” diode, just bigger?
I have only detailed the “safety” systems so far in this diagram, I have not detailed coolant, servo drive, servo motor, encoder, tachometer and other components, etc.


Attachment 263450
Overview

Attachment 263452
Cap to Servo Drive connections

Attachment 263454
Rectifier, Cap and Over voltage Brake

Many thanks for reading and any help is much appreciated,

Kim

[Al_The_Man]

With a 240v/120v control transformer one of the secondary terminals would be taken to earth ground right at the secondary terminal to set up a local neutral.
For AC coils, a r/c snubber would be used in place of the DC BEMF diode.
Al.

[accuartisans]

Al,

Many thanks, I was wonder what they were called (RC Snubber/Network) and it turns out I have about half a dozen of them that I can reuse! As for the grounding, I have read a many post that have done regarding "Grounding". So, will the source ground/neutral for the 220AC circuit also go to the "Earth Ground"?

Like this:

Attachment 263632

As I remember, there are many "pros" and "cons" as to also taking any "negative" leg from any DC power supply and add this to the "earth ground" as well, if my memory serves me correctly you were for this grounding method vs an isolated DC negative legs. Is that correct? and would you also apply the negative leg from the servo/rectifier capacitor to the earth ground as well?

Thanks again!

[Al_The_Man]

In N.A. the 220v is already grounded via the C.T. neutral, but when you add a 220v to 120v control transformer, the grounded neutral no longer exist's, so it is allowed to earth ground one of the secondary terminals, and make this a 'local' neutral, if not then you should fuse both secondary conductors instead of just the live conductor.
Per 120v Tfmr in the PDF.
The grounding of DC supplies common is arbitrary and up to the installer, your PC P.S. for example IS grounded in the supply itself.
My personal preference is to use equi-potential bonding and ground the common of supplies.
Al.

[accuartisans]

Al,

Got it! Thanks again.

Kim

[CATCH22]

I'd like to get some input for my wiring circuit design for E-STOP, Power On and Servo Drive Enable for the retrofit of my 3-Axis Bed Mill. It originally had a Delta 20 controller which I am retrofitting with LinuxCNC utilizing Mesa 7I80DB Ethernet and 7I77 Analog Servo interface cards. Also, I have purchased BE25A20 AMC servo drives to replace the older 1525 drives. Have this all up and running in a mocked up layout and now the wiring fun begins!

I am fairly good with “automotive” electrical/electronics (even the old positive ground systems) but clearly a learning novice to “real” electronics. For example I am confused by term “DC common” as I only know of +(positive) and – (negative) and I think DC common equals negative? I do know what AC common/neutral is however.

The spindle motor is a 3hp 3-phase motor that I plan on driving with a VFD. Therefore I planned for the need of 2 30A 220 1-phase to drive my machine. One 30A circuit will drive 2 isolated transformers, one for 120VAC that will drive 5vdc and a 24vdc power supplies and the other at 72VAC that drives the Servo power supply and drives/motors. The second 30A circuit will drive the spindle VFD.

At a high level I will try and explain the wiring diagram logic below, at least how I think it should be working.

Power on sequence:
The main power switch will power up the 120v AC transformer and both 5vdc and 24vdc power supplies.
Pressing the momentary power on button will energize “RLY1”, energizes “RLY4” which energizes both RLY2 and RLY3 and provides a “Power On and E-STOP OK” input to the interface board.

Relay RLY2 energized powers up the 72vac isolated servo transformer which provides power for the servo drives.
Relay RLY3 energized powers up the the Spindle VFD.

There is 24vdc supplied to the limit switches were if all the limit switches are “OK” will then energize “RLY5” to enable/disable the servo drives.

Note: The existing limit switches are capable and wired in such a way I can get a signal for when any of the limit switches break and a separate signal for what extent (+ or -) of the specific axes limit switch broke. The nice thing about this feature is the old controller has an “override” button that allows the servo drive to re-enable to jog only that axes off the opposite direction. This is nice as otherwise it would be difficult to mechanically move the axes as they are closed. I would like to preserve this capability, which I have as inputs to the interface board. This would aslo enable the “override” functionality.

E-STOP sequence:
If the E-STOP button is pressed then that drops the energized RLY1, RLY4 to RLY2 and RLY3, this drops all the power to the Spindle and Servos.

Limit Switch sequence:
Breaking a limit switch drops the energized RLY5 and then disables the servo drives. Is this adequate?

I've attached my wiring diagram for comments, input, etc. I started this diagram in sections of concern and added to it as I went along, so the actual layout of wiring isn't how I would actually wire it from a clean point of view. Remember, I'm a novice so yo aren't going to hurt my feelings and the symbols may not be to a electronics standard, but it is what I came up with using “Inkscape”. Also, I have my “Power Center” build layout completed, pictures below.

Several questions:
1) Do I use the “hard wire” approach to enable the servo drives via the limit switches? Or can I use the limit switch input to the interface card and then have an output to the servo drive enable relay 4?
2) I am unsure where to source what I need utilize the AMC “inhibit” pin. Noted in my diagram as well as the text for the pin from the AMC data sheet.
3) Is this a fairly “safe” wiring diagram?

Also, I don't show it on my diagram, but I will have a “fly back” diode on all the DC relays. Do I need something on the “AC” relays? Is it still a “fly back” diode, just bigger?
I have only detailed the “safety” systems so far in this diagram, I have not detailed coolant, servo drive, servo motor, encoder, tachometer and other components, etc.


Attachment 263450
Overview

Attachment 263452
Cap to Servo Drive connections

Attachment 263454
Rectifier, Cap and Over voltage Brake

Many thanks for reading and any help is much appreciated,

Kim

Hi I'm in the process of doing almost the same thing as you with the BE25A20 AMC drives, could you tell me what relay you used to enable the drives, and I also read that you need a resistor also. Would really appreciate any help you could give.
Thanks Mike