Chapter 6 ______________________________________________________________ Maintenance
VAISALA _______________________________________________________________________ 83
Cleaning RAINCAP
®
Vaisala RAINCAP
Rain Sensor should be cleaned every six months or
more often depending on the conditions.
NOTE
The measuring principle does not allow for proper ESD protection of the
RAINCAP
®
electronics, so you must follow the following instructions:
- Ground your hand first by touching grounded metallic parts of the
installation to remove excessive static charges from your body.
- Clean the RAINCAP
®
rain detector carefully with a soft, lint-free
cloth moistened with mild detergent. Be careful not to scratch the
surface.
- Check that the detector is free of ice and snow deposits.
Calibration
PWD22/52 has been calibrated at the factory. Normally, PWD22/52
needs no recalibration as long as the circuit boards are not changed, or
there is no call for warnings and alarms. The circuit boards need no
hardware calibration.
A periodic check every 6 months is recommended. The user checks the
visibility calibration using the PWA11 calibration kit. If the check shows
less than ±5 % change, recalibration is not recommended, because the
change is within the repeatability of the calibration procedure.
If any mechanical damage changes or weakens the optical measurement
path, that is, either the receiver or the transmitter, or the cross arm
supporting them, PWD22/52 must be replaced. If the receiver unit
(PWC22/52) or transmitter unit (PWT11) is replaced, both visibility and
contamination measurements need recalibration.
Visibility Calibration
The calibration is checked and adjusted with the PWA11 calibration kit.
The kit consists of a blocking plate and two opaque glass plates with
known scatter properties. The
ZERO, CHEC, and CAL commands are
used in the procedure. The calibration procedure checks two points; zero
scatter signal and a very high scatter signal. The zero signal is obtained
using a blocking plate and the high signal using opaque glass plates.
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