EKO INSTRUMENTS CO., LTD. Sunshine Duration Meter MS-093 Instruction Manual Ver.4
Pg. 6
4. Introduction
EKO Sunshine Duration Meter MS-093 has a specially designed and rotating mirror, which reflects the direct solar
radiation onto an especially flat pyroelectric sensor. This sensor outputs a differential coefficient as voltage, which
is proportional to the direct solar irradiance.
WMO defines the sunshine duration as time amount of direct solar irradiance which exceeds 120W/m
2
. MS-093
measures the direct solar irradiance that exceeds the threshold of 120w/m
2
, assuring reliable sunshine duration
data can be obtained. Internal CPU processes the signal sent by the sensor then outputs a pulse as sunshine
duration when the direct irradiance exceeds the threshold value.
EKO Sunshine Duration Meter MS-093 is a one-of-a- kind high performance instrument, which is used worldwide
in many applications such as ASOS (Automated Surface Observing System) by NOAA (National Oceanic and
Atmospheric Administration).
4-1. Main Functions
1. Very Precise Sunshine Duration Measurement
MS-093 uses pyroelectric sensor, which is one of thermal sensor; minimize the diffused sun light by extracting
this sensor output as derivative to the time and outputs the non-voltage contact pulse as output of sunshine
duration above the given threshold (120W/m
2
). Also the pyroelectric sensor has flat characteristics thus it
can correspond to the changes of solar spectral distribution changes by the climate.
2. Mirror
The mirror inside the sensor head rotates 100 times per hour
*1
by the pulse motor, and it reflects the direct
incident light to the light receiving element which uses the pyroelectric sensor at the rate of once per 36
seconds
*1
.
This mirror has diffuse characteristics only in the declination direction, thus it does not affect the output signal
by the declination changes. Without making any adjustments with mirror to the declination changes (
±
23.5
℃
), the light is directed to the center of the sensor; therefore, it does not require any data correction or
declination adjustments throughout the year.
3. Lightning Protection
As the countermeasures for induced lightning and lightning surge, MS-093 uses surge protector and does not
use microcomputer to prevent program going out of control.
In case of lightening surge which is unexpectedly large is applied to MS-093, latch-up phenomenon occurs in
the IC used on the internal circuit, and it sometimes causes to stop the mirror rotation. In order to restart the
measurements automatically, EKO recommends to use Reset Box (optional), which detects the mirror
rotation automatically and resets the power supply when the mirror is stopped.
*1
MS-093 also has a version with 120 revolutions per hour. With this version, the sunshine detection is
calculated once per 30 seconds.
