Honeywell SMV 3000 user manual Damping, Low Flow Cutoff for PV4

6.9 FlowConf Configuration - PV4, Continued

Damping

ATTENTION

Adjust the damping time constant for flow measurement (PV4) to reduce the output noise. We suggest that you set the damping to the smallest value that is reasonable for the process.

The damping values (in seconds) for PV4 are:

0.00d, 0.5, 1.0, 2.0, 3.0, 4.0, 5.0, 10.0, 50.0 and100.0

d Factory setting.

The electrical noise effect on the output signal is partially related to the turndown ratio of the transmitter. As the turndown ratio increases, the peak-to-peak noise on the output signal increases. See the Damping paragraphs in subsection 6.6 for a formula to find the turndown ratio using the pressure range information for your transmitter.

Low Flow Cutoff for PV4

For calculated flow rate (PV4), set low and high cutoff limits between 0 and 30% of Upper Range Limit for PV4 in engineering units.

•Low Flow Cutoff: Low (0.0 = default) High (0.0 = default)

Background

ATTENTION

You can set low and high low flow cutoff limits for the transmitter output based on the calculated variable PV4. The transmitter will clamp the current output at zero percent flow when the flow rate reaches the configured low limit and will keep the output at zero percent until the flow rate rises to the configured high limit. This helps avoid errors caused by flow pulsations in range values close to zero. Note that you configure limit values in selected engineering units between 0 to 30% of the upper range limit for PV4.

Figure 25 gives a graphic representation of the low flow cutoff action for sample low and high limits in engineering units of liters per minute.

If the flow LRV is not zero, the low flow cutoff output value will be calculated on the LRV and will not be 0 %.

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