Instruction manual

Troubleshooting
continued
RFT9739 Field-Mount Transmitter Instruction Manual 69
Before You Begin Getting Started Mounting
Power-Supply and
Sensor Wiring
Output Wiring Startup Troubleshooting
Overrange and sensor
error messages
If a sensor failure occurs, if the sensor cable is faulty, or if measured flow,
measured temperature, or measured density go outside the sensor
limits, the display produces one of the following messages:
• "Sensor Error"
• "Drive Overrng"
• "Input Overrange"
• "Temp Overrange"
• "Dens Overrng"
To interpret overrange and sensor error messages, use the transmitter's
fault output levels, a digital multimeter (DMM) or other reference device,
and refer to
Table 7-4
for corrective actions.
Unplug terminal blocks from the transmitter electronics module to check
circuits.
Slug flow
Programmed slug flow limits enable transmitter outputs and the display
to indicate conditions such as slug flow (gas slugs in a liquid flow
stream). Such conditions adversely affect sensor performance by
causing erratic vibration of the flow tubes, which in turn causes the
transmitter to produce inaccurate flow signals.
If the user programs slug limits, a slug flow condition causes the
following to occur:
1. The message display reads "SLUG FLOW".
2. The frequency/pulse output goes to 0 Hz.
3. mA outputs indicating flow rate go to the level that represents zero
flow.
The flowmeter resumes normal operation when liquid fills the flow tubes
and when density stabilizes within the programmed slug flow limits.
The user can also program a slug duration, from 0 to 60 seconds, into
the configuration of an RFT9739. If process density goes outside a slug
flow limit, flow outputs hold their last measured value for the period of
time established as the slug duration.
Table 7-5
summarizes possible slug flow errors and lists typical
corrective actions.
Output saturated
messages
If an output variable exceeds its upper range limit, the display message
reads "Freq Overrange", "mA 1 Saturated" or "mA 2 Saturated". The
message can mean the output variable has exceeded appropriate limits
for the process, or can mean the user needs to change measurement
units.
Table 7-5
summarizes possible output saturated messages and lists
typical corrective actions.