Interference with Probe Sensor

Merry Christmas

mannyb

Senior Member
Anyone experienced with fuel systems and fuel dispensers for C stores. A customer is having issues with alarm probe on their fuel monitoring system. The probe monitors fuel level but when 2 fuel grades are selected the probe goes into alarm but everything is working properly and for precautions they have replaced wiring and probes but still show alarm. The fuel monitoring equipment has been tested and show no problems so its suspected to be interfernce in wiring, The probe wiring and motor wiring are ran in separate conduits. The grpunds have all been checked for both LV at probes and HV for STPs. My question is how would you test for interference in a LV line?? i hope i explained the issue correctly. I am in a rush this morning.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
My ultimate go-to would be an oscilloscope with differential inputs.
If the signal is analog DC, I would try adding a filter capacitor at the receiver input(s).
 

mannyb

Senior Member
My ultimate go-to would be an oscilloscope with differential inputs.
If the signal is analog DC, I would try adding a filter capacitor at the receiver input(s).

one capacitor at each point? + and - and how would you size capacitor. I looked it up but I dont fully understand.
 

synchro

Senior Member
Location
Chicago, IL
Occupation
EE
I don't have any direct experience with this, but on page 24 of the installation manual for a fuel level probe from Veeder-Root it says:
"Some wired probe installs, that are subject to high levels of electrical interference, may require the installation of the dual-channel I.S. Circuit protector between the probe and the TLS console."
It appears that this circuit protector is for clamping surges, but I suspect that it also provides filtering if it can reduce electrical interference.

This indicates that interference can be an issue, and solutions are available for this company's products. But the vendor of the system being used by the customer, or a maintenance provider like Hal mentioned, should be contacted for support in your case.


 

mannyb

Senior Member
I don't have any direct experience with this, but on page 24 of the installation manual for a fuel level probe from Veeder-Root it says:
"Some wired probe installs, that are subject to high levels of electrical interference, may require the installation of the dual-channel I.S. Circuit protector between the probe and the TLS console."
It appears that this circuit protector is for clamping surges, but I suspect that it also provides filtering if it can reduce electrical interference.

This indicates that interference can be an issue, and solutions are available for this company's products. But the vendor of the system being used by the customer, or a maintenance provider like Hal mentioned, should be contacted for support in your case.




Thank U Friend.
 

mannyb

Senior Member
I just wanted to update that we resolved problem with interference in signal wiring about 2 weeks ago but thought maybe this will help the next person. The motors had VFDs or VFCs and they are pretty old models. The interference was coming from the drive powering the specific load and signal wire. We replaced the drives and solved the problem. I guess if I had mentioned that in original post someone would have picked up on problem.
 
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