Table 2-2: Troubleshooting
(continued)
Error
Recommended action(s)
Chord failure
•
Chord is hard failed, and meter is unable to obtain measurement
data from a pair of transducers.
—
If a chord is failed and no other transducers are failed or are
reporting status alerts, the issue is most likely isolated to this
pair of transducers or its cabling. Check the transducer wiring
for this pair of transducers to make sure connections are secure
and wired correctly.
—
Remove the transducer cable from the transducer and measure
the resistance with an Ohm meter.
•
For T-11 and T-12 transducers, remove the transducer cable
from the transducer and measure the resistance with an
ohm meter across the two pins on the back of the
transducer holder. If the value is over 2 ohms, replace the
transducers.
•
For T-21, T-22, T-32 and T-41 transducers, remove the
transducer cable and transformer assembly and measure
the resistance with an ohm meter. If the value is not 1
Mohm +/- 0.2 Mohm, try cleaning the pins with alcohol and
a small object like a toothpick to see if that lowers the
resistance. If not, replace the transducers. Measure the
resistance across the two pins on the transformer module
that lead to the electronics. If the value is over 2 ohms,
replace the transformer module. Measure the resistance
across the two pins on the transformer module that lead to
the electronics. If the value is over 2 ohms, replace the
transformer module. Measure the resistance across the two
pins on the transformer module that lead to the transducer.
If the value is not between 30 and 40 ohms for the T-21 and
T-41 transformer module, replace the transformer module.
If the value is not between 50 and 75 ohms for the T-22
transformer module, replace the transformer module. If the
value is not between 7 and 12 ohms for the T-32
transformer module, replace the transformer module. If
possible, measure the capacitance of the transducer with an
LCR meter. If the value is not between 450 and 600 pF for
the T-21 and T41 transducer, replace the transducer. If the
value is not between 215 and 350 pF for the T-22
transducer, replace the transducer. If the value is not
between 400 and 550 pF for the T-32 transducer, replace
the transducer.
•
For T-200 transducers, remove the transducer cables from
the transducers and measure the resistance with an ohm
meter across the two pins on the back of the transducer
capsules. If the values are over 2 ohms, replace the
transducer capsules. If the values are under 2 ohms, remove
the transducer capsules, clean and reapply the coupling
fluid to the front face of the transducer capsules, and
reinstall the transducer capsules. If this does not correct the
issue, replace the transducer capsules.
Maintenance and Troubleshooting Manual
Troubleshooting
00809-0600-3104
April 2022
Rosemount Gas Ultrasonic Flow Meters
17
