Electrical Connections; General Electrical Guidelines; Power; Output (Forward Flow And Reverse Flow) - Seametrics EX800 Series Instructions Manual

ELECTRICAL CONNECTIONS

General Electrical Guidelines

• Whenever possible avoid running control cables in
the same conduit with or bundled with AC power.
• Using shielded cable, be sure to connect shield to
ground at power supply end of the cable.
• Avoid routing flow sensor cables in close proximity to
a variable frequency drive.
• Recommended power and output wiring is shielded
twisted pair 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, especially with AC
line voltage fluctuation. Therefore 24V power supplies
must be regulated.
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.
Output
Forward Flow Output: This open-collector isolated
output does not supply power. 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. Grounding Guidelines:

Grounding Guidelines

Caution: The EX800 has a strong start and
run current. When using solar panels and
VRSLA batteries as a power source, use
caution to insure the EX-series sensor has
the -50 Low-power Option and that all Seametrics
products on the power circuit receive sufficient
voltage and current under all conditions. Failure to
do so will lead to unreliable operation and possible
damage to the unit/s. Please reference the technical
bulletin, 'Solar and Battery-Power Guidelines'
available on our website: seametrics.com
Seametrics • 253.872.0284
For best results, use a good quality earth ground, such as
metallic water piping or a driven ground rod, to ensure
a good connection to earth ground and good noise
suppression.
For Metallic Pipe: For optimum connection, clamp wire to
the piping a short distance to one side of the flow sensor
using an electrical grounding clamp. Connect the wire to
the earth ground and to one of the housing screws.
For Non-Metallic Pipe: Connect one of the housing
screws by wire to a good earth ground, such as metallic
water piping or a rod driven into the ground.
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 cable gland (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.
Earth Ground
Place Ferrite
Bead Here
Metallic Pipe
Grounding
Clamp
Grounding Diagram
Page 8
EX800 - SERIES INSTRUCTIONS
Housing Screw
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