Seametrics EX100-200 Series v.2 - Manual (Page 10)

Grounding Guidelines:
For best results, use a good quality earth ground, such as
metallic water piping, or a stake driven into the ground.
If the flow sensor is installed in metallic piping, for optimum
grounding clamp wires to the piping a short distance to either
side of the flow sensor using hose type clamps. Connect
these wires to the earth ground and to one of the housing
screws. (For non-metallic piping, this step is not needed.)
EX meters are usually unaffected by moderate levels of
electrical noise. In some applications performance may be
improved by taking the following steps:
• Use shielded twisted pair cable (Belden 8723 or
equivalent above ground or Alpha 35482 or
equivalent burial).
• Clamp a ferrite bead (Steward 28A2029-OAO or
equivalent) on meter signal/power wire within 3/4”
of the meter strain relief (tape or tie wrap in place if
necessary). See diagram below.
• IMPORTANT - Connect the cable shield ground wire
to ground, ONLY at power supply end of cable.
General Electrical Guidelines:
• Whenever possible avoid running control cables in
the same conduit with AC power.
• Using shielded cable, be sure that one end is
grounded.
• Avoid routing flow sensor cables in close proximity
to a variable frequency drive.
• Recommended power and output wiring is shielded
18-22 AWG control cable.
• Recommended voltage is 12-24 VDC. Note
that unregulated power supplies can vary from
nameplate voltage by a considerable amount. When
in doubt, use a regulated power supply.
See the Connections diagrams on the following pages for
the appropriate terminals.
Power: A 12 - 24 Vdc power supply capable of at least 250
mA current output is needed.
Forward Flow Output: This open-collector isolated output
does not supply power. It functions like a polarity-sensitive
switch closure. This pulse is generated in the forward flow
direction on the standard unit. (Reverse flow output is
available as an option).
Note: This output is limited to 6 mA at 30 Vdc maximum.
Reverse Flow Output: Reverse flow output is available
as an option. This open-collector isolated output does not
supply power. It functions like a polarity-sensitive switch
closure.
Note: This output is limited to 6 mA at 30 Vdc maximum.
Page 8
ELECTRICAL CONNECTIONS
GROuNDING DIAGRAM
Ground To
Metallic Pipe
Earth
Ground
hose Clamp
(Not needed for non-metallic pipe)
PLACE FERRITE bEAD hERE
AR
CH
IVE
D
(Includes Dates 5/05 to 9/06)