adccommunitymod (AutomationDirect) asked a question.
2 vs 3 wire RTD Sensors
Created Date: August 29,2012
Created By: dieseltwitch
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Im having a little bit of trouble filitering out VFD noise for my RTD sensors. the temperature is boucing about 20*F when any of my 11 VFD's are active. I have them all well grounded (NO LOOPS) I can't lower the Carrier Freq either.... I am using only a 2 wire RTD sensor, what I want to know is if I buy the 3 wires will it do any better?
Created Date: August 29,2012
Created by: Adisharr
Probably not as the additional wire is just for resistance compensation.
Are you using shielded cable on the motor end or doing any filtering on the drives inputs?
P.S. I hate inverter noise issues :o
Created Date: August 29,2012
Created by: dieseltwitch
Probably not as the additional wire is just for resistance compensation.
Are you using shielded cable on the motor end or doing any filtering on the drives inputs?
P.S. I hate inverter noise issues :o
No an No :( wasn't in the budget....
any ideas on how to filter the noise out? How about one of those ferrite core clap on things that go on headphones cables?
Created Date: August 29,2012
Created by: Adisharr
You may want to contact companies that make noise suppression devices to see what they recommend - I think units on the input and output would help tremendously. I have no idea of the cost though. I know the last time I looked at using specialty inverter motor cable it was very expensive.
Created Date: August 29,2012
Created by: Do-more PE
One thing that causes a lot of noise on the ground, not having the motor ground go back to the VFD chassis grounding point. See the GS drive manual for wiring the motor ground.
Created Date: August 29,2012
Created by: dieseltwitch
One thing that causes a lot of noise on the ground, not having the motor ground go back to the VFD chassis grounding point. See the GS drive manual for wiring the motor ground.
All Motors are grounded through the VFD. I have 200hp Worth of VFD's in the enclosure so buying noise suppression gear would be extremely expensive
VFD was way too expensive for this project.
Created Date: September 04,2012
Created by: kevindedwards
You could try filtering the RTDs in software. Write a low-pass filter routine that has a time constant of a few seconds. The VFD noise *should* average to zero. Not an ideal solution - keeping the noise out would be better. But, it may be good enough for your application, and only costs some of your time.
Created Date: August 29,2012
Created by: dieseltwitch
Im having a little bit of trouble filitering out VFD noise for my RTD sensors. the temperature is boucing about 20*F when any of my 11 VFD's are active. I have them all well grounded (NO LOOPS) I can't lower the Carrier Freq either....
I am using only a 2 wire RTD sensor, what I want to know is if I buy the 3 wires will it do any better?