Making sense of some power issues...

[mbcdev]

Good morning everyone,

I have freshly joined the forum but have been reading posts here for quite some time. Glad to be here as a member.

So, I recently started making some connections between my components. I don't think these are terribly relevant to what I'm actually asking, but here's what I have;

• 1 x Pokeys57CNC controller board
• 5 x HY-DIV268N-5A motor drivers (one spare)
• 4 x KL23H2100-35-4B stepper motors

I had just put everything together and wanted to do a simple test or two with the Mach4 software I installed, so here's what I did;

1. Connected one of the motors to one of the drivers.
2. Connected that driver to the controller board.
3. Installed a 5 amp fuse for the installed driver; this should probably eventually be a 3 amp fuse (or 3.5 amp if I can get it, since the motor has a 3.5 amp current), but I thought this would be alright, because...
4. I set the current on the motor driver to 1.2 amps

Here's what happened. I started jogging the motor, watching my z-axis move as it should, but as the motor would start, I heard a "bad" sound and then everything sounded normal. I kept moving the motor back and forth, making physical adjustments, trying to narrow in on the sound. Finally, I suspected the motor itself and not the mechanics, so I removed the motor and jogged it back and forth a few times to confirm. Sure enough, the sound was coming from the motor. As I was jogging the unmounted motor, there was a click and a plume of smoke from the controller! I was one HY-DIV268N-5A driver down!

Alright, so these things happen. But what I don't understand is exactly why it happened. I think this particular motor is probably bad, but shouldn't the motor controller have limited the current draw to 1.2 amps, thus preventing itself from having cooked? If I had put a proper fuse in place (probably a 1 amp fuse), would that have stopped my driver from going up in smoke?

I guess, generally speaking, I'm curious about how all of these values should be set. The motor draws up to 3.5 amps, the driver can provide up to 5 amps. I thought this was a good thing - have more available than is necessary. My plan was to choose a fuse based upon the motor current - 3.5 amp motor, 3.5 amp fuse. But everything I read says that fuses are two slow to protect any of the electronics anyway, so why bother?

Ok, I'll stop there - thanks in advance to anyone who can tell me what went wrong and to how to properly choose these values. Also, my apologies if this sort of information is covered elsewhere - I did a number of searches, but couldn't find anything that really talked about these particular issues.

Quick follow up - I just noticed that the 5 amp fuse for that controller actually blew as well as the motor driver itself. Not sure if this is good or bad. Anyway, the driver is definitely cooked.


Respectfully,
Marshall

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[Toinvd]

Check the motor that there is only connection between two wires ( two pairs ) and no connection between the pairs or between any of the four wires and the metal of the motor.
Next with a disconnected motor rotate it by hand and it should run "free" with no bad heavy points. You feel the magnets.
If you short one of the coils then rotating by hand must be heavy.
If this is all fine, next be sure to connect the wires correctly. Drivers don't like bad contacts, they like to start smoking in that case. Never connect or disconnect a motor wire while there is power on the driver.
Don't use a to high or to low input voltage on the driver ( I wouldn't go for 48V but use a 36V powersupply )
A normal 5A or 3A fuse will not protect the driver, but prevents further damage if the driver shorts.
Start again using one motor and one driver. Start at low RPM and low rampup

[mbcdev]

Hello Toinvd!

Thanks so much for your response and very sorry for taking so long to get back to this - I was unfortunately pulled away from this project for an extended period of time.

In any case, here's what I did;
1. I checked all my motors and all of my connections - everything seemed to be 100%.
2. I had a 12V 30A supply around, so I thought I'd hook that up and see how things worked. If I set the step to 1/16, everything worked fairly well! If I changed the step setting to anything larger than 1/16 though, the movement would stall after a few seconds and the motors would make a whirring sound - definitely don't understand this, wish I did.
3. Anyway, encouraged by my success at 12V, I ordered a 36V 16A supply, which arrived today. I replaced the 12V with the 36V and left everything else the same - 1/16 step and 2.5A setting on the motor driver. Things seemed to work quite nicely...for about 30 seconds, and then another puff of smoke - my third motor driver is now cooked!

So now I'm really at a complete loss. After destroying three HY-DIV268N-5A, my best guess as to what's going on is that these drivers are crap. I cannot imagine why they would pop with these settings;
* 48V @ 2.5A
* 36V @ 2.5A
but be fine at 12V @ 2.5A. They are rated for 5 amps, right?


Also, you mentioned RPM and ramp up - not sure what constitutes "low", but I can tell you I used the default in Mach 4;
* 2000 counts per unit
* 750 Units/Minute (Velocity)
* 10 Units/(Sec^2) (Acceleration)

I would imagine this would be fine, but perhaps not.

Anyway, very much interested in your thoughts and where I should go next with this. I believe I have four old ProboStepVX drivers in another project - I may rip those out and drop them in place in this new device, just to see if my problems go away. Lots of work for a test though!


Thanks,
Marshall

[Toinvd]

This sounds like it's oscillating. If the design isn't good and wiring not optimal, you can get oscillation which can destroy the electronics.
Your motor wires should not be running near the step and dir input wires. Best they would be shielded cables. And if the power wires from the power supply are long, it's good to have a capacitor close to the connection of the driver.
The ProbostepVX drivers won't work with these motors as they need a center tap on the windings. Your motors only have 4 wires ( 2 coils no center tap )
Have a look at some better drivers like DM542 or DM856 I use the DM542 on 3 different motors, and they all work fine

[mbcdev]

Good morning!

I now know without a doubt what was causing my issues - as I had feared, the motor drivers I was using, the HY-DIV268N-5A devices, have turned out to be more or less garbage. They seem to work so-so with a low current at 12 volts for some reason, but they perform far from how they are supposed to perform. Last night, I replaced them with four KL-5056E motor drivers that I got from Automation Technologies and my machine is running perfectly! Unreal how smooth and powerful this is - granted, I don't have much experience with CNC machines at this point, but I can tell you that these drivers work quite well. I will be using these, and Automation Technologies, again and again.

By the way, I sent out a question to Automation Technologies this past Saturday night around 9 PM EST, expecting an answer sometime Monday, hopefully in the morning. By 10 PM Saturday night, I had my answers from John at AT and placed my order before midnight. My new drivers arrived Tuesday! Responsiveness is a 10+, just like the product!

Ok, that's it - thanks to everyone who read my lengthy post and gave me advice, especially Toinvd.

Have a great day, onwards and upwards!


Thanks,
Marshall