Seametrics FT400-Series - Manual (Page 5)

Page 3
INSTALLATION
Connections. To connect the FT400-Series flow computer
to a flow sensor or an external device such as a chemical
metering pump, follow the Standard Connections diagrams
on pages 4-6.
If the FT420's 4-20 mA current signal is not required, connect
the power terminals to any 12-30 Vdc voltage source.
Dual Relay Output (Option -98). If you purchase the FT420
with option 98, the required component will come preinstalled,
and no extra procedures are required.
If you are retrofitting an existing installation of an FT420 with
the dual relay board, please follow the instructions below:
1) Peel the backing off of the double-stick tape and affix
it to the bottom of the relay board (part #100557).
2) Carefully attach the board to the FT420 as shown in
the FT420-98 Connection diagram on page 5. Be sure
that the red wire faces the “Sensor Input” side of the
FT420, and that the white wire faces the “Pulse
Output” side.
3) Connect the white wire to the “Pulse Scaled” positive
terminal, and the red wire to the “Power 4-20 mA”
positive terminal.
4) Connect devices to the relays as desired.
CAUTION: If output is being used to
control an external device, such as a
metering pump, do not connect the
device until programming is com-
pleted. If malfunction or incorrect
programming of the output could cause personal
injury or property damage, separate safeguards must
be installed to prevent such injury or damage.
-98 Relay Board Specifications
Output Voltage 0-130 VAC/DC
Output Current (each output)
Temperature
50˚ C 85˚ C
Current Limit 100 mA 50 mA
Max Pulses/Second 5
Contact Time Per Output 100 ms
CAUTION: When selecting a battery
for use with applications using the
FT420. Evaluate the application over
all anticipated operations and insure
the battery voltage does not, at any
time, drop below the minimum specified voltage, as
this will lead to unreliable operation and possible
damage to the unit.