AMERICAN ULTRAVIOLET Lesco SUPERSPOT MK III, Техническое справочное руководство

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KMM1002P
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5.0. Calibration
5.1. Optical Feedback Operation
Optical Feedback is designed to maintain constant exposure intensity over the lifetime of
the bulb for tight process control. It automatically compensates for the normal decay of
the bulb during its operating life, achieving a constant output to maintain uniform total
energy per cure cycle. A UV sensor is used to monitor the output intensity creating a
reference voltage that the power supply maintains by modulating the power delivered to
the bulb.
The variable power supply has a working dynamic range of electric power. When the
shutter is closed the bulb idles at the low limit of this power range. Once the shutter is
opened, the power supply will increase its output to reach the preset intensity level. If the
control circuit fails to achieve this preset value, the POWER ALARM indicator will
illuminate, after 5 seconds. This usually indicates a worn bulb, but always inspect the
reflector and filter to make sure they are not reducing the bulb output.
5.1.1. Optical Feedback setting
The Optical Feedback circuit can be set by adjusting the potentiometer located in the rear
of the unit while measuring the output of the lightguide with a calibrated NIST traceable
radiometer. Turning the potentiometer counter clockwise will lower the output while
turning it clockwise will increase it. Using this method it is possible to determine the range
of operation of the bulb by finding its Maximum and Minimum UV output values.
Adjusting the pot to the Maximum output (radiometer reading) will trip the Power Alarm
indicator when the shutter is open. The closer the UV output is set to its Maximum value
the less reserve the power supply will have to compensate for the bulb’s gradual decay.
The closer the setting is to the Minimum UV output, the more reserve power is available
to compensate the bulb. The Power Alarm indicates that the power supply no longer has
any reserve left to compensate the bulb. Replace the bulb and recalibrate the unit when
the Power Alert is on, to maintain the required UV output.
5.1.2. Optical Feedback Calibration
** WARNING **
Risk of electrical shock, voltage present between test probes and chassis
ground.
Refer servicing to qualified service personnel
Calibration needs to be performed when a new bulb or any optical element (bulb, filter and
reflector) is assembled into the unit.