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Reference Manual
00809-0100-4665, Rev AA
August 2010
C-5
Rosemount 8732
Troubleshooting
Ground/Wiring Fault
The transmitter detected high levels of 50/60 Hz noise caused by improper
wiring or poor process grounding.
1. Verify that the transmitter is earth grounded.
2. Connect ground rings, grounding electrode, lining protector, or
grounding straps. Grounding diagrams can be found in “Grounding”
on page 5-12.
3. Verify sensor is full.
4. Verify wiring between sensor and transmitter is prepared properly.
Shielding should be stripped back less than 1 in. (25 mm).
5. Use separate shielded twisted pairs for wiring between sensor and
transmitter.
6. Properly connect the wiring between the sensor and the transmitter.
Corresponding terminal block numbers in the sensor and transmitter
must be connected.
Ground/Wiring Fault
Functionality
The transmitter continuously monitors signal amplitudes over a wide range of
frequencies. For the Ground/Wiring Fault diagnostic, the transmitter
specifically looks at the signal amplitude at frequencies of 50 Hz and 60 Hz
which are the common AC cycle frequencies found throughout the world. If
the amplitude of the signal at either of these frequencies exceeds 5 mV, that is
an indication that there is a ground or wiring issue and that stray electrical
signals are getting into the transmitter. The diagnostic alert will activate
indicating that the ground and wiring of the installation should be carefully
reviewed.
HIGH PROCESS NOISE
DETECTION
The High Process Noise diagnostic detects if there is a process condition
causing unstable or noisy readings, but the noise is not real flow variation.
One common cause of high process noise is slurry flow, like pulp stock or
mining slurries. Other conditions that cause this diagnostic to activate are high
levels of chemical reaction or entrained gas in the liquid. If unusual noise or
variation is seen, this diagnostic will activate and deliver a PlantWeb alert. If
this situation exists and is left without remedy, it will add additional uncertainty
and noise to the flow reading.
Turning High Process Noise On/Off
The High Process Noise diagnostic can be turned on or off as required by the
application. If the advanced diagnostics suite 1 (D01 Option) was ordered,
then the High Process Noise diagnostic will be turned on. If D01 was not
ordered or licensed, this diagnostic is not available.