NuFlo MC-II Plus Panel Mount, User Manual, Page: 32 / 92

MC-II Plus WP-PM Flow Analyzer
26 May 2005
See Appendix A for installation and field wiring of the pulse output feature. An
optional circuit assembly can be added to the standard circuitry of the main board to
provide two sets of dry contact outputs. See Appendix H of this manual for the
installation and wiring of the Relay Pulse Output Board.
Configuring the 4-20 mA Rate Output
The MC-II Plus Flow Analyzer has a 4-20 mA output feature that represents rate.
This feature can be configured to represent any flow rate range within the range of
the flow meter. The 4 mA setting, though typically configured for zero flow, may be
configured for a minimum desired flow rate. A flow rate equal to this minimum
programmed flow rate will result in an output of 4 mA. If the flow rate falls below the
4 mA minimum programmed flow rate, the current output will go as low as 3.9 mA
and the
4-20.oUt/Err Lo error message will be displayed. The 20 mA setting,
though typically configured for the maximum turbine meter flow rate, may be
configured to any flow rate above the flow rate that the 4 mA output will represent. A
flow rate equal to the 20 mA programmed flow rate will result in
an output of 20 mA. If the flow rate rises above the 20 mA maximum programmed
flow rate, the current output will go as high as 22 mA and the
4-20.oUt/Err Hi error
message will be displayed. Flow rates in between the minimum and maximum flow
rates will result in an output of current between 4 mA and 20 mA according to the
following calculation:
[ ]
MIN MIN CURR
MIN MAX
MIN MAX
OUT
I RATE RATE
RATE RATE
I I
I
+ − ×
⎥
⎦
⎤
⎢
⎣
⎡
−
−
=
Where:
=
OUT
I The output current
=
MAX
I The maximum current output which is 20 mA
=
MIN
I The minimum current output which is 4 mA
=
MAX
RATE The maximum programmed flow rate
=
MIN
RATE The minimum programmed flow rate
=
CURR
RATE The flow rate
Not only are the minimum and maximum flow rates programmed into the MC-II Plus
Flow Analyzer, but the 4 mA and 20 mA outputs are keypad adjustable for hardware
calibration of the system, insuring maximum output accuracy.