[matth]

You gear # needs to be set at 500 not 1000, your steps/per will change when you use this number, 500 this is the best number to use for step/dir, if using analog +/- 10v then you can take advantage of the gearing

If you think it is a switching problem then you should use a solid state relay, between the Drives and the power supply, to turn the power off as per the above schematic, this is how servo drives are normally wired, it should not be needed,but something must be happening to cause this, there may be a spike/or something happening when the power is turned off, that the Drive Brain does not like, it is very strange,that I have never had this, and I use a lot of these drives, the power here is only 120v ac, not sure that this would make any difference to your 220v ac supply Matth also was using 220v supply

The only thing I can think of is that we are all using external capacitors which have a much greater capacitance than the small ones on the DMM BOB. I think it only has 4700uf for all the connected drivers. I was using a 10,000uf cap per drive and Tomas is using 3x4700uf caps per drive (don't know about Bl@ckrat). Because of this the power rails in our setups would take a considerably longer time to discharge than if using the DMM BOB.
Probably just never came up as a testing scenario. These are a little different from a normal AC servos in that with them you are disconnecting the AC which is normally internally rectified and smoothed. The equivalent to the schematic posted would be to disconnect the AC to the SMPS supplying the 48v. That is how my system was setup originally, what needs to be done is between the caps and the drives do as to disconnect the DC power immediately. Maybe I'll drag these drives out and do some testing. I was always happy with the performance it was just the uncertainty upon power up that was the issue.

[mactec54]

matth

There may be something in this,Bl@ckrat I think is using the Dmm Breakout Board, unless he has changed his setup,so his only difference to what we use is the Power 220v to our 120v yes the disconnect would have to be between the Drive and the Caps, isolating the caps from the drive, even Tomas using 3 may of been to many, the Dmm system only has 2x 4700uf for up to 4 axes

When using linear power supplies the filters should be at the power supplies, most likely the Caps you were using are the right size for your power supply, but may only need ( 1 ) for each supply out of your transformer

[Bl@ckrat]

Hey guys

I'm not using caps ....

I'm using the kit straight outta the box as I got it , with smooth stepper

I'm on 230v

Sorry for what is prolly a dumb question , but what is the point of the caps if the switch or relay is after the cap ?

Are the two caps on the bob insufficient ?

Surely if I just have the switch or relay between the bob and the drive that would work ? I have my three psu in parrallel , they go into the bob and then the four drives are also in parrallel

[Bl@ckrat]

Also has anyone ever had this problem with the dyn3 system ?
I might swop over as the dyn3 was intended for this machine in the first place

[mactec54]

Hey guys

I'm not using caps ....

I'm using the kit straight outta the box as I got it , with smooth stepper

I'm on 230v

Sorry for what is prolly a dumb question , but what is the point of the caps if the switch or relay is after the cap ?

Are the two caps on the bob insufficient ?

Surely if I just have the switch or relay between the bob and the drive that would work ? I have my three psu in parrallel , they go into the bob and then the four drives are also in parrallel

The only difference I see is that you are using a higher ac voltage, 230v our voltage is 120v ac, this should not be a problem if everything is Grounded correctly

The caps are to smooth out the DC power, because you are using there Breakout Board, if your 48v DC is going to and out from their Breakout Board then you are using their built in Filter, so don't need to have any other caps

Yes if you switch the power between the Bob & the Drives you would only need one solid state relay, why use a solid state rely, so you don't have to worry about switching noise

I know that some had a noise problem with the Dyna 3 drives, If a power filter was added, that took care of any noise, Dmm recommended that they be used with a power filter

A Photo of how you have your power supplies wired to the Breakout Board, and Breakout Board to the Drives, this would help also to show how you are wiring your system

[matth]

Another way to do it might be to add a suitably sized bleed down resistor across the power rail after the smoothing Caps.
This would drain down the caps much faster but you'd need to know the input impedance of the drives to size it correctly.

I was under the impression that the caps where really for spike suppression of any back EMF created by the motors on overrun. I was using SMPS for my DC rail which are regulated so the caps weren't for smoothing. Probably because of this they were vastly oversized.

[mactec54]

Another way to do it might be to add a suitably sized bleed down resistor across the power rail after the smoothing Caps.
This would drain down the caps much faster but you'd need to know the input impedance of the drives to size it correctly.

I was under the impression that the caps where really for spike suppression of any back EMF created by the motors on overrun. I was using SMPS for my DC rail which are regulated so the caps weren't for smoothing. Probably because of this they were vastly oversized.

Yes they were there to help protect the SMPS from any spikes, but also to filter the power a little better, the SMPS power supplies that Dmm sold with there system would not of been as good as what you were using, the Drives control most of the back EMF, there would be very little EMF that would get back to/hit the caps

I though that you had used a linear power supply, which you would of needed at least ( 1 ) Cap the size you had, so with the quality SMPS that you used, you would not of needed any Cap's at all, may be one for safe measures at the Power supply to help protect it from anything going back that could affect the SMPS

The best thing is not to have the Caps there at all, and only at the power supply if it needs them to filter the rough DC power

[matth]

Yes they were there to help protect the SMPS from any spikes, but also to filter the power a little better, the SMPS power supplies that Dmm sold with there system would not of been as good as what you were using, the Drives control most of the back EMF, there would be very little EMF that would get back to/hit the caps

I though that you had used a linear power supply, which you would of needed at least ( 1 ) Cap the size you had, so with the quality SMPS that you used, you would not of needed any Cap's at all, may be one for safe measures at the Power supply to help protect it from anything going back that could affect the SMPS

The best thing is not to have the Caps there at all, and only at the power supply if it needs them to filter the rough DC power

That's interesting. It would be a better setup without them. If I get the time I might pull one of these drives out of storage and try a few tests on the bench. When they were in production on my machine I really couldn't deal with the issues as there was no clear resolution hence swapping them out. But I would like to get to the bottom of this issue and then possibly use the kit in a new build.

[Tomas_J]

My system still looses eeprom or drive settings

So, you haven't made the mod, I suggested...
Ok, you can try another mod - buy a pair of 24V 30-60W halogen bulbs, connect them in series to the dmm drive power rail. That should help. As a bonus you will have additional lightning

[mactec54]

So, you haven't made the mod, I suggested...
Ok, you can try another mod - buy a pair of 24V 30-60W halogen bulbs, connect them in series to the dmm drive power rail. That should help. As a bonus you will have additional lightning

I think Bl@ckrat may have switched his power rail ,but has not replied back, he started another thread, and said he was running, but did not say what he had done

You have not said in your posts if you were using 230V ac supply, or have a 120v ac supply, this is something we are looking at, I don't think your above suggestion is a very good solution

[matth]

Putting a couple of bulbs across the rail would be a bit of a jury rigged solution but would be a very effective and relatively safe way of bringing the DC rail to 0volts as quickly as possible after power off.

It would also be very easy to implement if just for a quick test.

[Tomas_J]

You have not said in your posts if you were using 230V ac supply, or have a 120v ac supply, this is something we are looking at, I don't think your above suggestion is a very good solution

It doesn't matter. 120V, 220V, 380 V or 10KV AC main - Dyn2 drives are powered from 48V DC - so I'm using PSU. You can ask, if I'm using one or more psu, switching or simple transformer, but it matters only how fast Dyn2 supply voltage falls after power off...

[mactec54]

It doesn't matter. 120V, 220V, 380 V or 10KV AC main - Dyn2 drives are powered from 48V DC - so I'm using PSU. You can ask, if I'm using one or more psu, switching or simple transformer, but it matters only how fast Dyn2 supply voltage falls after power off...

Obvious we are not going to get anywhere with an reply like that, I think everybody knows what the drive voltage is,48 DC to 52v DC we are just trying to see why there were these problems,and what you have done that is different with your install

I have installed lots of the Dyna 2 drives over the last 6 years, ( more than a 100 ) and have never seen or had this problem, I'm testing right now, with the most basic, with a power cord to a power supply, just pulling the plug, & pushing it back in, still with zero change in the Drive parameters

[matth]

It doesn't matter. 120V, 220V, 380 V or 10KV AC main - Dyn2 drives are powered from 48V DC - so I'm using PSU. You can ask, if I'm using one or more psu, switching or simple transformer, but it matters only how fast Dyn2 supply voltage falls after power off...

Lol, indeed.

I was using 3 x switch mode power supplies balanced and tied together into a 48v bus. Each drive was feed from this bus via a suitably sized breaker and then a 10,000uf 100v cap.
I had the exact same issues as you. Maybe 1 in 10 power ups the drives would of randomly changed the gain and mode settings. This didn't happen to all the drives at once but would happen to different drives on occasion.
The changes were definitely happening between power down and power on. I would check the settings before power off and again immediately after power on and they would of changed. I never saw a loss of settings during running.

[Tomas_J]

I'm testing right now, with the most basic, with a power cord to a power supply, just pulling the plug, & pushing it back in, still with zero change in the Drive parameters

How quick Dyn2 power supply voltage falls down in you configuration?

[mactec54]

How quick Dyn2 power supply voltage falls down in you configuration?

Around .5 of a second with ( 3 ) 750w motors attached, without the motors attached bleed down time is almost 4 minutes, both ways have been switched like 200 times,for this test, with no change to any of the Drives parameters

[Tomas_J]

Try to connect more capacitors to make it 2 times slower...(with motors connected). Or maybe it's drive firmware related.
A bit off-topic, but two week ago one our Dyn2 drive failed for no reason (at least I can't imagine one). No, not lost settings It even works, but only with slow acceleration - in normal mode it can lose position with or without throwing fault... Less than a year old, ~400h mileage. And dmm-tech haven't offered any discount for replacement...

[mactec54]

Try to connect more capacitors to make it 2 times slower...(with motors connected). Or maybe it's drive firmware related.
A bit off-topic, but two week ago one our Dyn2 drive failed for no reason (at least I can't imagine one). No, not lost settings It even works, but only with slow acceleration - in normal mode it can lose position with or without throwing fault... Less than a year old, ~400h mileage. And dmm-tech haven't offered any discount for replacement...

Adding more capacitors, would be crazy, you have way too many capacitors in your system

I thought this might happen when you switch off the power at the drive, if this happens when your machine is running, there is nowhere for any excess, regen voltage to go this will kill the drives, like Estop with it up to speed, this will kill the drive

The Caps are only there to smooth out any Dc ripple, from the power supplies, there system only has a total of ( 2 ) Caps, 63v 4700uf this is for up to 4 power supplies, ( 1 ) 1000uf is more than enough for the whole system

[Tomas_J]

Adding more capacitors, would be crazy, you have way too many capacitors in your system

So, maybe Dyn2 manual was written by some crazy people - see attachment...

[mactec54]

So, maybe Dyn2 manual was written by some crazy people - see attachment...

No not at all, as I said by switching the power to the drive as you have, you have stopped the flow of back regen voltage, that would normally go back through their Caps that they had set up on their Breakout Board, in your set up the Drive is taking all the regen voltage & over time it will fail