Line noise
LOI menu path Diagnostics → Variables → Line Noise
The line noise parameter shows the amplitude of the line noise. This is a read-only value.
This number is a measure of the signal strength at 50/60 Hz. If the line noise value exceeds
5 mV, then the ground/wiring fault diagnostic alert will activate.
9.7 High process noise detection
The high process noise diagnostic detects if there is a process condition causing an
unstable or noisy reading that is not an actual flow variation. A 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 flow variation is seen, this diagnostic will activate and deliver an
alert. If this situation exists and is left without remedy, it will add additional uncertainty
and noise to the flow reading.
9.7.1
Turning high process noise on/off
LOI menu path Diagnostics → Diag Controls → Process Noise
The high process noise diagnostic can be turned on or off as required by the application. If
the advanced diagnostics suite 1 (DS1 Option) was ordered, then the high process noise
diagnostic will be turned on. If DS1 was not ordered or licensed, this diagnostic is not
available.
9.7.2
High process noise parameters
The high process noise diagnostic has two read-only parameters. It does not have any
configurable parameters. This diagnostic requires that flow be present in the pipe and the
velocity be greater than1 ft/s (0.3 m/s). The low and high frequency signal values depend
on the line size.
Low frequency signal to noise ratio (SNR)
LOI menu path
Diagnostics → Variables → Noise Analysis → Low Freq Noise
This parameter shows the value of the signal to noise ratio at the coil drive low frequency.
This is a read-only value. This number is a measure of the signal strength at low frequency
relative to the amount of process noise. If the transmitter is operating in low frequency
mode, and the signal to noise ratio remains below [25] for one minute, then the high
process noise diagnostic alert will activate.
Advanced Diagnostics Configuration Reference Manual
November 2019 00809-0100-8782
94 Rosemount
®
8782 Slurry Magnetic Flow Meter Transmitter with HART Protocol
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