NuFlo MC-II Plus Panel Mount, User Manual, Page: 36 / 92

MC-II Plus WP-PM Flow Analyzer
Appendix A1
A1-2 May 2005
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.
External Power Supply
The External Power Supply feature is provided to allow the Panel Mount MC-II Plus
Flow Analyzer to be powered by an external power source, therefore extending the
life of the internal lithium battery. The internal lithium battery provides a power
supply backup in the event that the external power source fails. This allows the
Panel Mount MC-II
Plus Flow Analyzer to retain calibration data and continue
operation during a power failure. The Panel Mount MC-II Plus Flow Analyzer is
connected to the remote power supply by a two-conductor cable. The power supply
and cable must be capable of supplying between 8 and 30 VDC @ 10 mA. The
External Power Supply wiring diagram is located on page A1-12.
This capability is available only if the 4-20 mA Rate Output is not used.
Caution must also be taken when using the Flow Meter Frequency Output with the
External Power Supply since both share a common negative (-) connection. The
power supplies for both features must share a common negative (-) terminal or be
totally isolated from each other.
4 to 20 mA Rate Output
The 4-20 mA Rate Output provides a linear current output that represents flow rate.
This output requires a two-conductor cable connected to an 8 to 30 VDC, 20 mA
minimum, power supply (voltage required dependent on loop resistance) and a
current readout device located in the remote location. The 4-20 mA Rate Output
current loop also powers the Panel Mount MC-II
Plus Flow Analyzer, therefore
extending the life of the internal lithium battery. The internal lithium battery provides
a power supply backup to retain calibration data and to continue accumulating
volume in the event that the 4-20 mA current loop fails. The 4 to 20 mA Rate Output
wiring diagram is located on page A1-13.
The section in the manual,
Configuring the 4-20 mA Rate Output , provides
information regarding the setup of the 4-20 mA output feature.
The 4-20 mA Rate Output and the Flow Meter Frequency Output circuits are not
isolated from each other. If both outputs are required, verify that the power supplies
and readout devices associated with each output are completely isolated from each
other.