The DP flow transmitter on the DCS showed a reading of zero.
However, in the field, the transmitter was outputting 4.11mA current, which represents 12% of its total output range.
(Understanding Transmitter Behavior):
DP Flow transmitters often have a predefined range over which they operate. This range is typically represented as a percentage of their maximum output current or voltage.
In our case, the transmitter considers any current output below 12% of its range as indicating a zero flow condition. This is due to a lower cut-off threshold set at 12% of the output range.
(Action Taken and Observation):
To troubleshoot and correct the issue, the decision was made to increase the flow rate by 15%.
After increasing the flow by 15%, the transmitter on the DCS returned to showing a normal, non-zero value.
(Conclusion and Explanation):
The root cause of the zero reading on the DCS was the lower cut-off threshold set on the transmitter. When the actual flow fell below 12% of the transmitter’s output range, it interpreted this as zero flow.
Increasing the flow rate by 15% brought the transmitter’s output above the 12% threshold, thereby registering a non-zero flow value on the DCS.
This indicates that the transmitter was functioning correctly but was configured with a lower limit threshold that caused it to indicate zero when the flow was below this threshold.
In Summary:
the issue was due to the lower cut-off threshold set at 12% of the transmitter’s output range.
This threshold caused the DCS to indicate zero flow when the transmitter output was below this value. Increasing the flow rate by 15% resolved the issue by bringing the transmitter’s output above this threshold, allowing the DCS to display the correct flow value.
#Troubleshooting #sensor #DCS
