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Chapter 5. Trial Operation and Adjustment
Handling Precautions
• Ensure that the ultraviolet detector does not detect ultraviolet rays other than
those from the burner flame.
Sources of ultraviolet radiation (other than the burner flame) that can activate the
AUD flame detector include the following.
Examples:
Ultraviolet ray sources 1371 °C or hotter red-hot furnace wall (within 50 cm
from wall)
Spark of an ignition transformer or welding arc
Gas laser
Sunlamp
Germicidal lamp, ultraviolet lamp, fluorescent lamp
Strong flashlight (toward ultraviolet sensor)
Gamma ray and X-ray sources X-ray diffractometer, gamma-ray analyzer
Electron microscope
X-ray machine
High-voltage vacuum switch
High-voltage capacitor
Radioactive isotope
Any other ultraviolet, gamma, or X-ray source
z
Measurement of flame voltage
This device shows the flame voltage on the 7-segment display. The voltage can be
checked by changing the display using the DISP switch on the front of the unit.
Checking the flame voltage is the best way to determine whether or not the location
of the flame detector is appropriate.
The flame voltage should be checked during installation and servicing. Checking it
once per month or more can prevent shutdowns due to insufficient flame voltage.
Start the device and measure the voltage under various conditions, such as at
startup and during normal operation. Check to make sure that the flame voltage
remains stable at 2.0 V DC or more. (The recommended flame voltage is 2.0 V DC
or more and it must be stable.)
If this stable voltage cannot be achieved, the problem may be caused by one or more
of the following. In such a case, do a thorough inspection.
• The power supply voltage or frequency is not correct.
• The air supply pressure or air-fuel ratio is not correct.
• The flame detector is not correctly wired.
• Open circuit
• Short circuit
• High-resistance short circuit of the lead wires due to humidity or dirt
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