allen bradley kinetix

Hello,

My customer wants me to come out and look at this servo drive. See attached picture. I am not at all familiar with this Allen Bradley Kinetix setup. He says 6500 module is faulting on an overvoltage code, but he is going to get the exact fault code that it displays. meanwhile, i am trying to understand how the system works.

Can you explain what each of these three modules are and what they do and how they work together? Thanks in advance!

ok try this

lesmar96 said:

Hello,

My customer wants me to come out and look at this servo drive. See attached picture. I am not at all familiar with this Allen Bradley Kinetix setup. He says 6500 module is faulting on an overvoltage code, but he is going to get the exact fault code that it displays. meanwhile, i am trying to understand how the system works.

Can you explain what each of these three modules are and what they do and how they work together? Thanks in advance!

Click to expand...

That is Ethernet/IP based servo motion control. Looks like a single axis rack. Module on Left is Power Module (Integrated Axis and Power) and Ethernet/IP Header. Your IP Address is 192.168.1.11 based on thumbwheel setting.

The second module is the connection for the Servo Motor, Encoder Feed Back, and Digital I/O. Note this is a SAFE OFF Drive and most like supports SAFE off and SAFE SPEED. Check the electrical schematic, this drive will only function with the SAFE OFF inputs satisfied.


The module on the right may just be a dummy filler cover on a 4-slot rack.


The picture is shown with power OFF. You best resolve is to be under power with the fault code scrolling across the digital marquee. There will be succinct cause, and corrective course of remedy listed in the User Manual available on the Rockwell Automation Literature Library.


Regards


Plastic

Power Converter Module, Axis Control Module, External Shunt module.

If the system is faulting on overvoltage, there's almost certainly something wrong with the Shunt module and/or the brake resistor connected to it.

Ken Roach said:

Power Converter Module, Axis Control Module, External Shunt module.

If the system is faulting on overvoltage, there's almost certainly something wrong with the Shunt module and/or the brake resistor connected to it.

Click to expand...

Sorry for my miss-information on the third module.

Thank You Ken,

The schematic would reveal the last module would be a shunt to brake resistor.

OP has not described the application yet, but if shunt and brake are involved, there may be a large mass that needs rapid deceleration.

OP Question: Long established application, now problematic?
OR
New Integration?

Plastic

Ken Roach said:

Power Converter Module, Axis Control Module, External Shunt module.

If the system is faulting on overvoltage, there's almost certainly something wrong with the Shunt module and/or the brake resistor connected to it.

Click to expand...

The quick and dirty test for the brake resistor is to lift the green connector above the shunt module and check for continuity on the large leads, if no continuity check the 700 volt 50 amp fuse in the resistor cage. The resistor needs to be at least 4 ohms if it's any less you will be changing the fuse often. By the way if it is the fuse do yourself a favor and put a long zip tie around the middle. you can then replace the fuse by just opening the lid and dangling the fuse by the zip tie, instead of totally disassembling the cage.

Plastic said:

OP Question: Long established application, now problematic?
OR
New Integration?

Plastic

Click to expand...

This has been in operation for awhile. I don't know how long, they have had some trouble with this in the past, they tried several things, including putting a line reactor in, and it had worked for about the last year without any problem. Now it starts making issue again and they can't get it resolved. They are calling me to come do power quality analysis on the incoming power because they think there are spikes coming in.

I am thinking possibly regen could be an option as well. What does the shunt module do?

We had a bunch of strange issues with a 6500 (don't remember if that code was one of them). Step 1 of AB's troubleshooting advice was to reseat the connectors. Of course, this sounded like typical "blah, blah, blah" stuff before the real troubleshooting instructions.

Reseating the connectors fixed everything! Apparently the 6500's in particular had issues with the connectors. So I'd advise your first step to pull and reseat all electrical connectors.

OK, so up front let me say that I know little about the Kinetix products. However, if resetting connectors is a known fix for errors then I would say that they probably have a contact area that is exposed to the environment leading to oxidation on the connection points. This would lead to increased resistance which I could see causing overload errors. The higher the resistance the more current it will take to get the voltage through. At some point that will rise above the capabilities of the device causing an overload. If resetting the connectors fixes the problem I would look for a way to isolate them from the environment.

I forgot to mention that some really good electrical contact cleaner would be a good thing to bring with you when going on site. Having said that, make sure Rockwell is OK with using contact cleaner on the device before using it.

Firejo said:

At some point that will rise above the capabilities of the device causing an overload.

Click to expand...

We are having an overvoltage fault, not overload.

Can someone explain to me what is the point of and use of this shunt module. The customer told me that it runs very fast and stops very often. This code usually comes up when the motor is trying to stop. Then if it faults, the motor just coasts.

With what I know, that would make sense if their is an issue with there braking system. If someone could explain how it works in more detail that would be great. Thank you.

lesmar96 said:

We are having an overvoltage fault, not overload.

Click to expand...

Again, not knowing much about the Kinetix unit;
An increase in resistance (on the output) will increase the load demand which the unit should respond with an increase in supplied current which will increase the voltage demand.
An example I currently have is via a PowerFlex 4m drive. I'm using it in a display for AF2018 and it's running a fan. The fan I was going to use apparently has a problem and it's measured resistance is high (compared to spec). The drive tried to start it but faults with an over voltage error. My understand of that error is that the current demand on the output is higher than the drive can supply.

To be fair I am guessing on your situation but it makes sense to me that if resetting connections has fixed similar issues before than resistance on the connections is the likely culprit. Besides, cleaning them can't hurt.

Hopefully our colleague jraef will be along shortly, as he is an expert on how VFDs and servos do braking. I will give it an amateur shot at explaining.

In general when you use a VFD or servo to decelerate a load, the motor acts like a generator and puts energy back into the drive. That causes the DC bus to rise up to near its limit, so the power has to go somewhere.

On a multi-axis system, sometimes that power is used up by other drives that are turning motors that require power.

On this system, there's only the one axis module, and the load is decelerating frequently and quickly.

The shunt module has a big power transistor inside that connects the DC bus (in fast pulses) to a big resistor mounted somewhere near this system, which literally dissipates the power as heat into the air.

Sometimes systems can run nominally just fine and then something changes in the supply, and the source power goes up a few volts, causing the DC bus voltage to go up a few volts, and increasing the amount of voltage that needs to be bled off the system to keep the bus under its limit during deceleration.

That might be a reason why the incoming power is suspected to be part of the problem.

But the first thing that should be looked at is the shunt assembly and its resistor and fuses. If it's not working, nothing's going to work.

Thanks, Ken for the explanation. it makes sense to me.