Old Plasma table retrofit - Sanyo Denki PY2 amps

[derekmccoy]

Thanks @ross I have read that guide before and Hypetherm also says to only ground at one end. However, I don't know if I'm not getting this quite right or I have a flawed understanding of what ground is, but this machine is wired as outlined in the manual figure attached below and that clearly shows (to me) grounding at both ends. Plus many other people saying to ground at both ends so you can understand my confusion I hope.

@breezy The motors are mounted to the table and therefore grounded to it's chassis (which is obviously earth grounded). The factory Sanyo Denki cable connector coming out of the encoder has 9 pins: 6 for data, 2 for DC+- and one for the cable shielding which is the thicker wire. This shielding on the encoder cable goes back to the drive and is grounded through the connector housing into the drive chassis. There's an earth ground bolt at the bottom of the drive that goes to an earth bus bar. I've checked and there's continuity between 1. the table chassis and the motor bolts 2. the motor bolts and the encoder cable shield 3. The cable shield and the CN2 connector housing 4. The connector housing and the earth terminal. I also checked the cable shield against all of them and there's obviously a connection.

Is this right or wrong? Because to me that is grounded at both ends. I have taken photos if that explains it better. Thanks for your help guys, it's appreciated.

 

[darkoford]

This topic is exactly what I am looking for.
Thank you all for your selfless help.
I have parts of similar waste plasma SAF Plasmatome 25, PY2a015a3-al, 300W servomotors. The problem is to test their correctness. I would use some classic USB BOB or Arduino for testing.

 

[Ross]

Hi Derek,

All the yellow arrows look normal and don't worry about them.

The green arrow will be grounded to a star point on the metal cabinet and runs to the earth rod in the floor, if you have dry ground drill the hole larger than the ground rod so you can poor water down it so often!

Star point on cabinet must have metal to metal contact!

If you look at the video you will see how I grounded the motors as well.

 

[derekmccoy]

@darkoford Yes, same parts that I have in this table. I'm interested on how you would test the servos so please update on your progress. If by testing you mean tuning, you will either need the RP-001 "remote operator" handheld unit, or a cable and software running on a Win9x machine. I have the RP-001 but have only used it to change parameters for position control. I have not performed auto-tuning yet but I will if I notice any weird behaviours once Masso is in control. Also, I have spoken to some servo engineers and several have mentioned the need to replace the capacitors on the drives every 5 years or so to keep them accurate.

@ross Yep, I've watched that video about 5 times haha. As I have several others on your channel. My aim is to have the table running just like yours, hopefully with a scribe. The grounding of the parts is not what I'm confused about, it's the encoder cable shield. It's grounded both to the drive chassis (and hence the control box chassis and then AC earthed) and to the motor chassis (and hence the table chassis then the star point terminal). I can do either both or not, it's very quick and easy to just replace the RJ45 connectors with unshielded ones so it will break the ground connection at the motor end.

 

[darkoford]

Quote from derekmccoy on June 28, 2020, 10:41 pm

Also, I have spoken to some servo engineers and several have mentioned the need to replace the capacitors on the drives every 5 years or so to keep them accurate.

Interesting. I have been repairing that plasma for 10 years and have had no problems with the capacitors and as far as I can see they have never even been changed. In my absence the plasma is wasted so I am not sure of the correctness of these servo components. Otherwise the most common plasma failures were on that relay BOB.

I also have the same situation with Burny 3 Servo DC motors and drivers for which I am looking for some solution to use via MACH or similar.

 

[derekmccoy]

@darkoford. As you have the same table, I'm interested to know what you are doing.

We're ripping out the old CNC controller, plasma cutter and torch and replacing them with Masso G3, a compact inverter cutter and a new torch. The control box is coming down because the original design of it being mounted on the gantry is not good at all. It added a ton of weight to it and you had to walk along with it while jogging. Potentially dangerous too (I'm attaching a photo of the table in it's original setup in case others are curious). I'm extending the motor cables and putting the control box on a stand beside the table where its out of the way and running cables from Masso to a podium style stand where the monitor and keyboard will be. Not sure if this is ideal but I'm figuring it out as I go along.

 

[darkoford]

Plasmatome 25 replaced with Plasmatome B 30, Nertajet300.

 

[derekmccoy]

Ok, so you upgraded to a larger table? What are you doing about the CNC controls? Are you keeping the large transformer plasma cutter?

 

[darkoford]

Yes, transformers plasma cutter 300A.

Part of the X-axis of the old Plasmatoma 25 I used for an oxygen cutter.

 

[derekmccoy]

@darkoford

I wonder if you can help me. I was too keen when ripping out the old controls and ripped out the main circuit switch, estop and extractor control panel. As it happens, I still need these controls. I can guess where some of the wires are meant to go like the ones labelled 0,24 etc but I m not sure how it was wired into the contractor. It wouldn t be too much to ask you to have a look at your control panel to see how it s meant to be wired?

 

[darkoford]

The factory where the plasma cutter is located, Covid-19. I don t know how long that will last so if it s not urgent I m taking photos when this pandemic is over.
There are only some parts of the old plasma in my workshop.
The wires are marked with numbers that should match the markings on the connectors.
The first (black) button 1 starts the program and the same function
The red button interrupts the program. These two functions are also on the touch screen
The middle white button only turns on the torch and while it is on below (white) the control lights up.
To the right is the E stop button and the red triangle control lamp if the E stop or one of the limit switches is activated.

If I understood correctly, do you connect it to MASSO? I guess it all connects directly to MASSO.

 

[derekmccoy]

Quote from darkoford on June 30, 2020, 6:58 am

The wires are marked with numbers that should match the markings on the connectors.
The first (black) button 1 starts the program and the same function
The red button interrupts the program. These two functions are also on the touch screen
The middle white button only turns on the torch and while it is on below (white) the control lights up.
To the right is the E stop button and the red triangle control lamp if the E stop or one of the limit switches is activated.

If I understood correctly, do you connect it to MASSO? I guess it all connects directly to MASSO.

Maybe your machine is different, but the controls on the left turn the 3 phase extractor fan on and off. This is pretty simple, just a standard contactor setup.

The triangle you are right, its e-stop or limit switch alarm which you have to press to reset. This is the safety relay and contactor wiring bit that I cannot figure out. The limit switches and e-stop leads used to plug into the old controller board, I think they need to be hard wired into the safety relay. The other issue is that this is a 24VAC circuit. Ideally I want it plugged into Masso but that's 24VDC. Also, Masso doesn't have a hard limit option, the limit switches would have to be wired into the e-stop circuit in series. I'm also not sure how to wire this into Masso in a way that the reset button would work. Masso is a bit too simple. If an e-stop is hit, ES goes low. All the user has to do is just release the e-stop and ES would go back to high, powering the motors again. The safer option is the way this was wired originally which is e-stop is pushed, safety relay turns off control power and the alarm light turns on, the user has to release the e-stop, press the reset button and make sure the alarm light goes off, then push the start button to power the motors back on. Does your Plasmatome Digisaf have a touchscreen? The thing is 30 years old.....

@masso-support Can you see a way Masso could be wired in like this? All e-stops and limits have dual NC and NO switches, maybe I could wire Masso into the NO switches and create a secondary e-stop circuit while the NC switches are wired into the safety relay? Either that or maybe wire the e-stops and limits into Masso and make the ES output go to a relay that then triggers the safety relay?

The middle white button engages main circuit power (motors), this makes the amplifiers ready (snake animation on the 7 seg LED). It's needed here in case e-stop or limit switches turn the motors off. Currently I'm bypassing this with a switched jumper which is very dangerously hanging off the terminal blocks. Ideally I want to do this myself without having to get an industrial electrician in.

If anyone knows how this is wired, it would be of great help.

 

[darkoford]

Machine is different. E-stop and limit swich = 24V

This is all that is left of the 25 models. The CNCzone has my query for SAF. A user from Yemen has some documentation that did not suit me.

 

[derekmccoy]

Yea, everything in that photo is scrap apart from the drive, the motor, the contractor and the fuses.
This is what this one looked like a couple of months ago, before I started ripping the old crap out:

 

[darkoford]

The components are the same but the layout is different. Only the SAF can do that.

 

[derekmccoy]

Have tried acquiring a new drive and motor for the z axis to replace the existing brushed DC motor which wad no encoder, just a tach. Got a second hand PY2 amp from China which arrived today and I tried testing it with my Y axis motor. I made sure the parameters were set and turned it on. It started jerking and throwing overload alarms. I may have some parameters missing but I didn't even try to move it. I'm thinking I have a faulty drive but I can't know for sure, I'm not a servoengineer. I'll wait for the Z axis motor to arrive and try again without a load.

@darkoford If it is the drive, would you be willing to sell the PY2 amp you have left?

 

[darkoford]

Don't worry, your servo drive is working. Do you have a "running eight" on the segment display? I had such a problem on the plasma, jumping like a wild horse. The problem is in the position search, or the poor contact of the encoder wires. New assembly requires Reset to BOB.
Did you install a regenerative resistor? 100 Ohms / 50W.
The Z-axis on that plasma is THC, why are you moving it?
I have 2 pairs of Amplifiers and a motor but for now I would not sell. I have to try to run them.

 

[derekmccoy]

@darkoford

Position search?

I can t reset, that old board is in the scrap bin. Masso is there now. Yes I put a 100ohm 25W resistor like the other drives have.

The Z axis motor was a brushed DC motor moved by the old controller. To get a working Z axis, I need a drive that will talk to Masso. So I bought a used PY2 from eBay and tried testing it with the Y axis motor but it s jerking. I get the snaking 8 but after a few seconds it jerks, moves a few mm then I get a 2 alarm which is overload.

 

[darkoford]

The servo motor encoder is in a position, PY2 remembers the last position of the encoder and MASSO has its own position. A reset is required to sync.

Perhaps to compare the connectors of the plasma encoder and the new PY2 - wire layout.

The 25W resistor was too weak for me, so I used 50W.

The original SAF THC works very well. If MASSO has the possibility of input of a THC voltage divider it should have been used.

 

[derekmccoy]

Interesting.

The manual mentions clearing the encoder (ECLR) using either pins 35,36 or the remote operator, however this is only for absolute encoder, not incremental. Not sure if it will help, but I will try it.

Also, this doesn't make sense to me because I have unplugged all 3 motors to make extended cables, moved the axis by hand and plugged them back in. The drives didn't need any resets.

I think it might be tuning?