New Build: SYIL X4 CNC Mill, Clearpath SDSK, C86ACCP & Centroid Acorn

All things related to the Centroid Acorn CNC Controller

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teknic_servo
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Re: New Build: SYIL X4 CNC Mill, Clearpath SDSK, C86ACCP & Centroid Acorn

Post by teknic_servo »

Hi Clay,
You bring up some good points that deserve some further clarification.

The section of the ClearPath manual that you posted is specifically regarding the connecting and disconneting of power cables. The purpose of this sequence is to prevent the arc (spark) when a live connection is made (or removed) to the motor. The repeated arcing at the connector can cause damage to the terminals in the connector. By removing the AC power going to the power supply, it prevents this arcing nature because there is no voltage.

You are correct that the E-Stop should be wired on the AC side of the power supply (sorry Marty). For safety certifications, this is the only way to get certified. It is also a good idea for a DIY machine. If the power supply is left "energized" by disconnecting the DC side of the power supply, there is "some potential" for that energy to get distributed even after the E-stop is pressed. If the AC line going to the power supply is interupted, this risk is eliminated. As you mentioned, you can also take advantage of the regen circuitry of the IPC-5 intelligent power center during deceleration.

I should make one more clarifying statement. There is a dynamic brake function in the motor that is set "on" by default when the motor ships from the factory. The ClearPath dynamic brake (not to be confused with a spring-applied power-off brake) shunts the regenerative energy produced by the motor in a power off, regenerative enregy condition. The amount of braking power that can be dissipated by the motor during deceleration depends on the size of the motor and the style of motor winding used (P, S, or D winding).

The dynamic brake function will be disabled when the encoder stops moving for 1 second. So if the motor is left with the dynamic brake configured from the factory, the motor is not truly "free-wheeling" when power is removed with an E-stop.

Hope this helps.
Tom T.
Last edited by teknic_servo on Tue Apr 06, 2021 8:36 am, edited 1 time in total.
carboncymbal
Posts: 80
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Re: New Build: SYIL X4 CNC Mill, Clearpath SDSK, C86ACCP & Centroid Acorn

Post by carboncymbal »

teknic_servo wrote: Fri Apr 02, 2021 3:36 pm Hi Clay,
You bring up some good points that deserve some further clarification.

The section of the ClearPath manual that you posted is specifically regarding the connecting and disconneting of power cables. The purpose of this sequence is to prevent the arc (spark) when a live connection is made (or removed) to the motor. The repeated arcing at the connector can cause damage to the terminals in the connector. By removing the AC power going to the power supply, it prevents this arcing nature because there is no voltage.

You are coprrect that the E-Stop should be wired on the AC side of the power supply (sorry Marty). For safety certifications, this is the only way to get certified. It is also a good idea for a DIY machine. If the power supply is left "energized" by disconnecting the DC side of the power supply, there is "some potential" for that energy to get distributed even after the E-stop is pressed. If the AC line going to the power supply is interupted, this risk is eliminated. As you mentioned, you can also take advantage of the regen circuitry of the IPC-5 intelligent power center during deceleration.

I should make one more clarifying statement. There is a dynamic brake function in the motor that is set "on" by default when the motor ships from the factory. The ClearPath dynamic brake (not to be confused with a spring-applied power-off brake) shunts the regenerative energy produced by the motor in a power off, regenerative enregy condition. The amount of braking power that can be dissipated by the motor during deceleration depends on the size of the motor and the style of motor winding used (P, S, or D winding).

The dynamic brake function will be disabled when the encoder stops moving for 1 second. So if the motor is left with the dynamic brake configured from the factory, the motor is not truly "free-wheeling" when power is removed with an E-stop.

Hope this helps.
Tom T.
Thanks for the clarification! It’s great to hear that the servos won’t be damaged by these types of e stops with high inertial loads.

Thanks! It’s always great to hear from you guys on the forum!

-Clay
martyscncgarage
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Re: New Build: SYIL X4 CNC Mill, Clearpath SDSK, C86ACCP & Centroid Acorn

Post by martyscncgarage »

Clay,
I have followed Centroid schematics in my build. Centroid uses an appropriately specified contactor to break DC voltage and current to its All in One DC FROM the DC power supply (Bridge rectifier, filter capacitor, transformer) The contactor must be rated for the voltage and current. Those are the contactors I use. (Eaton/Moeller and have spoken with their staff about their ratings). Centroid Engineers design and build their cabinets that way.
Please see attached All in One DC Schematic as an example. (That contactor is carrying about 155VDC across its contacts for example, and the drive is on the load side of the contactor)

Teknic documentation says it is permissible to disconnect DC power. So, I followed the traditional course as depicted in the schematic. If that is not correct, then Teknic should address or clarify it.
IPC-5 Disconnect.PNG
Respectfully,
Marty
Attachments
S14747 Mill, 220 110VAC, ALLIN1DC, Direct 110VAC Rectification, Spindle Reversing Contactors.pdf
(301.9 KiB) Downloaded 11 times
Reminder, for support please follow this post: viewtopic.php?f=20&t=383
We can't "SEE" what you see...
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RogDC
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Re: New Build: SYIL X4 CNC Mill, Clearpath SDSK, C86ACCP & Centroid Acorn

Post by RogDC »

Marty,
I understand your logic following the All-in-One schematic. However on the Acorn schematic utilizing the 100 Ohm Resistors and the C86ACCP, the contactor disabling the motor DC voltage is not included.

As the Enable- line is run thru the E-Stop on the Centroid Schematic and the C86ACCP utilizes Relay 1 to disable the motors in an E-Stop condition, I am trying to understand the need to remove the AC or DC power from the Clearpath motors in an E-Stop condition.

Following the latest wiring diagram for the Acorn with multiple SDSK Teknic motors provided by Centroid and following the wiring diagram from my spindle manufacturer, When I create an E-Stop condition the motors disengage, the spindle stops, and I get an Emergency Stop notification which pops up in CNC-12. With the Clear Path motors configured to move to the commanded position after a fault, and +24V provided on the Teknic power distribution board, the servos move to the commanded position when the E-stop is released and motion is commanded on the VCP or Wireless pendant.
martyscncgarage
Posts: 7883
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Re: New Build: SYIL X4 CNC Mill, Clearpath SDSK, C86ACCP & Centroid Acorn

Post by martyscncgarage »

It's good practice to remove power from servo motors during a fault or Estop condition. It's the only way you can nearly ensure there is no unintended axis movement.

I run the VFD common through the Estop contactor as well. In my build I am using 4 contacts on the contactor. 1 to enable C86ACCP, for VFD common (controlling FWD/REV) and I am running DC+ and DC- from the Teknic power supply through two contacts. Spears the current across two contacts instead of one. Overkill? Perhaps.

I personally choose to treat my small conversions as if they were large conversions.
Marty
Reminder, for support please follow this post: viewtopic.php?f=20&t=383
We can't "SEE" what you see...
Mesa, AZ
teknic_servo
Posts: 23
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Re: New Build: SYIL X4 CNC Mill, Clearpath SDSK, C86ACCP & Centroid Acorn

Post by teknic_servo »

All-

There are many ways to skin a...potato (dodged that one). I do some things at home that probably would not pass the OSHA or CE certification boards. That said, I feel safe, trust my work, and know how my devices should be used.

That said, and for clarity, the recommended procedure (or required in some instances) for removing power in an E-stop condition is to remove power from the 75VDC power supply. This leaves the bus power for the motors disabled. The logic inside the motors can be kept active with the 24VDC power supply that is "throttled back" so that it cannot move any motors under its own power. In this way, nobody that sticks their arm inside the machine under an E-stop will end up being called "lefty" because the motors unexpectedly move. (however, an axis can still potentially drop, right?)

The message is not intended to say that Centroid is "wrong" or Marty is "wrong" but more a matter of degree of compliance. If you are at home and not going to get your machine certified by a saftey group, follow the method you believe in to keep you safe. Sometimes certification requirements can be taken to an extreme, and I get it. Do I persoanlly consider removing machine power from the DC side of the power supply to be safe enough? Perhaps. But I am not allowed to fully endorse it based on many conversations with certification companies. Carry on...

Tom T.
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