Dwyer EFS2 - Manual (Page 4)

metallic Pipe
Earth
ground
grounding clamp
inStallation
Page 4 Page 5
ElEctrical connEctionS
grounDing Diagram
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 to 22 AWG control cable.
• Recommended voltage is 12 to 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 tpages 6 & 7 for the ap-
propriate terminals.
Power: A 12 to 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. 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.
PlacE FErritE bEaD HErE
Full PiPE rEcommEnDationS
Possible Problem:
Allows air pockets to form at sensor
better installation:
Ensures full pipe
Possible Problem:
Post-valve cavitation can create air pocket
better installation:
Keeps pipe full at sensor
Possible Problem:
Air can be trapped
better installation:
Allows air to bleed off
Housing
Screw
grounding guidelines:
For best results, use a good quality earth ground, such as
metallic water piping or a driven ground, 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 a wire from the housing screws
to a good earth ground, such as metalic water piping or a rod
driven into the ground, as shown in the “Grounding Diagram”
below.
Series EFS2 & IEFS 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.