Emerson 8800C User Manual

4-9
Hardware and Software Maintenance and Troubleshooting
Shedding Frequency Out Shedding frequency out is probably the easiest point to measure and
interpret. It is the final waveform after all filtering has taken place. It
is the flow signal that is sent to the microprocessor to be processed into
outputs. Check this point first, as it will allow you to see the final
waveform (after filtering) before it goes to the microprocessor.
TESTING PROCEDURES Use the test functions to verify that the flowmeter is functioning
properly, or when you suspect component failure or a problem with loop
performance, or when instructed to do so as part of a troubleshooting
procedure. Initiate each test with the HART Communicator or other
HART-based communications device. See Diagnostics/Service on
page 3-3 for details.
Symptom Corrective Action
Clean Signals at TP1 and
Shedding Frequency Out, But
Incorrect Output
Basics
• Perform basic checks for incorrect 4–20 mA
output problem (see Basic Troubleshooting -
Model 8800C Smart Vortex Flowmeter on
page 4-3).
• Perform basic check for pulse output.
• Check and correct configuration parameters in
this order:
K-factor, service type, materials, units, process
temperature, damping value, 4–20 mA trim,
filter tracking, density, density ratio, pulse
mode, pulse scaling, line size, pipe diameter,
LRV, URV, LP corner, trigger level, and low flow
cutoff.
• Refer to Advanced Troubleshooting on page 4-6.
• See Appendix E: Electronics Verification for
electronics verification procedure.
• Refer to Table 4-1 for further troubleshooting.
No Pulse at
Shedding Frequency Out
Basics
• Check TP1.
• Check electronics via Flow Simulation Mode
(see Appendix E: Electronics Verification).
• Check electronics with frequency external
generator (see Appendix E: Electronics
Verification).
• Check that sensor impedance >10 Megohms.
Replace sensor if necessary. (See Replacing the
Sensor on page 4-15.)
• Measure sensor capacitance at SMA connector
(100–200pF).
Noisy Signal at
Shedding Frequency Out
Basics
• Simulate signal with frequency generators or
Flow Simulation Mode (see Appendix E:
Electronics Verification).
• Optimize filter (gas); increase filtering of low
pass filter.
• Consult factory.
Missing Pulses at
Shedding Frequency Out
Basics
• Low back pressure.
• Viscosity too high.
• Density too low.
• Check sensor.
• Too much filtering. Check signal/trigger level.

Emerson 8800C Specifications

General

Brand	Emerson
Model	8800C
Category	Measuring Instruments
Language	English