KROHNE VFM 3100 EN - Manual (Page 36)

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Sensor switch
Sensor
switch
Ground wire
Sensor wires
EXT STD
Figure 25. Preamplifier Assembly
Integral Mounted VFM 3100
• Mount the new preamplifier to the metal shield using the original
screws. See Figure 22.
• Feed the yellow and brown sensor wires through the strain relief
clamp on the bottom of the preamplifier board. Tighten the
clamp and connect the sensor leads to the terminal block.
The color coding is important. Check to see that this is correct.
See Figure 25.
• Set the sensor switch to “STD” for standard temperature sensors
and to “EXT” for extended range temperature sensors.
• Before placing the preamplifier into the housing, bend the re-
taining tabs of the metal shield outward slightly to ensure a snug
fit against the housing walls. See Figure 18. Align the mounting
slots with the screw holes for mounting the electronic module.
• Once the preamplifier is in place, connect its four wires
(brown-red-yellow-orange cable) to the color coded terminal
block on back of the electronic module.
• Connect the output signal leads (red-blue, and yellow-green
cables) to terminal blocks on the electronic module, following
the color code on the label.
• Prior to mounting the main electronic module in the housing,
bring all the cables from preamplifier and the housing neatly
together as shown in Figure 18.
• While pushing the slack in the cables away from the back of
the electronic module, tie the cables together at two places,
using plastic tie wraps.
• Locate the electronic module in the housing by aligning the
preamplifier shield with the mounting holes.
• Rotate the electronic module one full turn clockwise before
mounting. This will help prevent the wires from being pinched.
Locate the electronic module over the mounting holes, align the
preamplifier, and tighten the captive mounting screws.
• Perform Post-Assembly Dielectric Test. Refer to page 37.
Replace threaded housing cover.
Remote Mounted VFM 3100
• Mount the new preamplifier on the mounting plate using the
two screws. Refer to Figure 23.
• Feed the yellow and brown sensor wires through the strain relief
clamp on the preamplifier board. Tighten the clamp and connect
the sensor leads to the terminal block. The color coding is
important. Verify that it is correct. See Figure 25.
• Connect (brown-red-orange-yellow) cable from preamplifier to
one side of the two-sided terminal block on the mounting plate.
See Figure 23.
• Before placing assembly into the junction box, connect the four
(brown-red-orange-yellow) wires entering the junction box
through a conduit opening, to the other side of the terminal
block on the mounting plate (following the same sequence as
the cable from the preamplifier). See Figure 26.
• Place mounting plate with preamplifier in the junction box and
mount it using the two mounting screws.
• Perform Post-Assembly Dielectric Test. Refer to page 37.
Replace the threaded junction box cover.