Onicon FT-3500 - Diagnosing Electrical Noise Issues

FT
-
3500 ELECTROMAGNETIC FLOW METER
ONICON Incorporated 727.447.6140 Page 57 onicon.com
Diagnosing Electrical Noise Problems
When diagnosing electrical noise problems, it is important to understand that one of four possible conditions are likely
to exist. They are as listed in the table below. In order to minimize the eects of noise, it is helpful to understand which of
the following conditions are present.
Earth Connection at Flow
Meter
Pipe / Fluid Earth
Connection
Expected
Noise
Level
Possible Remedies
Good earth connection
≤ 25 feet from ow meter
Pipe & uid are
connected to earth
Low None required
Good earth connection
≤ 25 feet from ow meter
Pipe & uid are not con-
nected to earth
Moderate
A separate earth connection can be made
directly to the metal pipe or to the uid. Non-
metallic pipes may require grounding rings
installed upstream and downstream of the
meter location.
Poor earth connection
Pipe & uid are
connected to earth
Moderate
Removing the earth connection at the ow
meter may reduce the noise level. If this is a
long wire run, break the connection where the
wire connects to the cable coming out of the
ow meter. If noise level is still too high, locate
a better earth connection for the ow meter.
Poor earth connection
Pipe & uid are not con-
nected to earth
High
Locate a better earth connection for the ow
meter. If noise level is still too high, locate a
better earth connection for the pipe or uid.