6
3.
Route scanner wiring a sufficient distance from ignition and other high voltage or high current
wiring to avoid electrical interference. Interference from ground currents, nearby conductors,
radio-frequency emitters (wireless devices), and inverter drives can induce false flame signals.
In some applications shielded cables can help reduce interference with the shield connected to
ground at the control end only. The wire type and its capacitance (picofarads or microfarads) to
ground may cause low signal problems, so a grounded shield can decrease the signal due to the
cable's internal capacitance. Multiple sensor leads run together without shielding may cause
interference or “cross talk”, so the shield or flexible armor must be grounded to prevent this sit-
uation.
THRESHOLD ADJUSTMENT
The MBCE-UV module is equipped with a flame pull-in threshold adjustment capability. This fea-
ture allows the user to dial in the appropriate flame signal threshold for the internal flame relay to
engage. When set, the flame signal strength must be greater than the threshold before the MBCE-UV
can signal "FLAME ON".
The adjustment can be made at the front faceplate potentiometer with the aid of a small flat blade
screwdriver. A clockwise adjustment of the potentiometer decreases the flame pull-in threshold of
the MBCE-UV module allowing the MBCE to pull-in at “small” flame conditions. Likewise, a
counter-clockwise adjustment of the potentiometer increases the flame pull-in threshold of the
MBCE-UV module allowing the MBCE to pull-in at “big” flame conditions. The 4-20mA output of
the MBCE-UV module signals 5.5mA at the pull-in threshold.
0°
270°
view showing “clockwise”
adjustment - decreasing
pull-in threshold.
• Apply proper grounding technique when adjusting the threshold potentiometer
• The adjustment potentiometer is recessed about 3/8” from the surface. Do not
screw driver into the product as this may damage the product.
• Ensure that the screw driver is centered on the adjustment slot to facilitate
• Do not apply excessive force as only a minimum force is needed for adjustment.
• The overall rotational angle of adjustment is three quarter turn (270 degrees).
over extend the
proper adjustment.
NOTICE
Do not over extend.
