You don't need to disconnect the shields at one end on the power conductor shields. Those are normally connected at each end.
Dave On 1/22/2016 5:23 PM, Jim Craig wrote: > I spent all afternoon looking for and trying to remove ground loops. I > think I found all that I can eliminate. I have a couple minor ones due > to the mounting of my PC motherboard/SSD that I don't think I can remove > without making new mounting fixtures. > > I did find one that I was sure was going to fix the issue. My encoder > breakout board that converts the honda connectors to RJ45 connectors had > the power ground going to chassis ground due to the mounting bolts. I > fixed that and removed that ground loop. I was sure that would fix the > issue but it did not. > > Also the shields on the servo motor power cables are grounded at both > ends in the motor and at the drive side. I disconnected the drive side. > I am not sure if this is a good idea or not as It could pose a safety > hazard. > > And for everyone's information the encoder cables are shielded, shields > grounded at the control board only, the signals are differential and I > am STILL having this issue. > > Anyway after all of this the noise is still present when running the GS1 > drive for the coolant pump. I think I will try to source a run capacitor > and switch back to a contactor for start stop on the coolant pump. > > The filter that I am using on the GS1 drive is a Tyco Corcom 5VB1. I > don't have an operating scope to look at the noise on the lines. > > Thanks for the feedback everyone. Should have listened to Andy 6 months > ago and went with the run capacitor then! ; ) : ( > > Jim > > On 1/22/2016 3:52 PM, Dave Cole wrote: >> Are you using decent filters?? >> >> GS1 and GS2 drives tend to pump a lot of RF noise up the power supply line. >> I've used the AD filters with good success. I think the one I used was >> about $80. >> If you are using cheap Ebay filters.... sometimes you get what you pay for. >> >> Have you put a scope on your AC lines to see if the filters are >> effective?? I suspect they are not. >> Re-routing your drive to motor leads is also sometimes effective. Keep >> them as far away from low voltage wiring as possible. >> >> Dave >> >> On 1/22/2016 12:51 PM, Jim Craig wrote: >>> Hey all, >>> >>> I have been troubleshooting some noise that I have on my servo encoders. >>> I have isolated the noise source to be the 1/4hp Automation Direct GS1 >>> VFD that I have running my coolant pump. If the coolant pump is not >>> running then there is no noise on the encoders and the machine maintains >>> correct positioning. If I turn the coolant pump on then the encoders get >>> false signal that in turn changes where the machine thinks it is. This >>> problem showed up immediately after I retrofitted the machine this last >>> summer. I have just now been able to diagnose where the issue is >>> originating. >>> >>> In attempts to improve the situation I have done the following. >>> Installed EMI filters on the supply lines to both the coolant and >>> spindle vfds. >>> worked on ground system to try to isolate the noise. >>> rerouted the coolant pump motor power cable completely away from >>> any other cables and completely away from the machine. >>> >>> All of these things have failed to improve the noise issue. >>> >>> I also tried the following to try and diagnose the issue. I disconnected >>> the coolant pump motor cable from the coolant pump vfd. Disconnected the >>> spindle motor from the spindle vfd. Connected the coolant pump to the >>> spindle vfd. Note that the spindle vfd is a 3.0hp Automation direct GS2 >>> drive. >>> >>> When I did this and ran the coolant pump via the spindle vfd there was >>> no noise on the encoders. >>> >>> Does anyone have any ideas on how to get rid of this issue. I really >>> want to make some parts but I can't with the noise issue. >>> >>> I talked to a EE buddy of mine and he mentioned running both motors >>> (spindle and coolant pump) off the same 3.0hp GS2 drive just to get me >>> going. What do you think about this? Will running two different sized >>> motors on the same VFD cause any issue. Right now I don't run my spindle >>> in reverse so I would not have any trouble with the coolant pump running >>> backwards. >>> >>> I talked to Automation Direct and they said that the GS1 is more prone >>> to noise than the GS2. I am contemplating getting a 1/2hp GS2 to replace >>> the GS1. >>> >>> So frustrated right now. >>> >>> Let me know if you have any ideas. >>> >>> Thanks, >>> >>> Jim >>> >>> ------------------------------------------------------------------------------ >>> Site24x7 APM Insight: Get Deep Visibility into Application Performance >>> APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month >>> Monitor end-to-end web transactions and take corrective actions now >>> Troubleshoot faster and improve end-user experience. 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