Troubleshooting
Table 10-7
Frequency output problems and recommended actions
continued
Problem
Possible causes
Recommended actions
Consistently
incorrect frequency
measurement
•
Output not scaled correctly
•
Incorrect flow measurement unit
configured
•
Check the frequency output scaling. See
Section 10.20 .
•
Verify that the measurement units are
configured correctly for your application.
Erratic frequency
output
•
RF (radio frequency) interference
from environment
•
Check for radio frequency interference.
See Section 10.12.
10.8
Use sensor simulation for troubleshooting
You can use sensor simulation to help distinguish between legitimate process noise and externally
caused variation. For example, consider a receiving device that reports an unexpectedly erratic flow
value. If sensor simulation is enabled and the observed flow rate does not match the simulated value,
the source of the problem is likely to be somewhere between the transmitter and the receiving device.
Important
When sensor simulation is active, the simulated value is used in all transmitter outputs and calculations,
including totals and inventories, volume flow calculations, and concentration calculations. Do not enable
simulation mode unless your application can tolerate these effects, and be sure to disable simulation
mode when you have finished testing.
10.9
Check power supply wiring
Prerequisites
To verify wiring, you will need a copy of the installation manual for your transmitter. To check power
supply wiring for the 9739 MVD transmitter, you must remove the electronics module from the
transmitter housing base.
Procedure
1.
Before inspecting the power supply wiring, disconnect the power source.
If the transmitter is in a hazardous area, wait five minutes after disconnecting the
power.
2.
Verify that the correct external fuse is used. An incorrect fuse can limit current to the transmitter
and keep it from initializing.
3.
Ensure that the power supply wires are connected to the correct terminals.
4.
Verify that the power supply wires are making good contact, and are not clamped to the wire
insulation.
5.
Inspect the voltage label on the inside of the field-wiring compartment.
The voltage supplied to the transmitter should match the voltage specified on the label.
6.
Reapply power to the transmitter.
190
Micro Motion 9739 MVD Transmitters