EKO MS-802 User Manual

EKO INSTRUMENTS CO., LTD. - Pyranometers MS-802/802F/402/402F/602 - Instruction Manual Ver.13
Pg. 14
5) When a pyranometer with a ventilation unit is installed, connect the power cable. Make sure to
ground the earth terminal (green cable) attached to the power cable (AC versions only).
*When the power is switched on, check whether the ventilation unit is working properly by placing
your hand above the pyranometer to feel the air stream.
5-3. Measuring Solar Irradiance
In order to determine the global broad-band solar irradiance, the measured output voltage [mV] of the
pyranometer has to be converted by the calibration factor into the units of the solar radiative flux, which is
Watts per meter squared (W/m
2
). The output can be measured with a high-resolution (at least 5µV)
measuring instrument, such as a voltmeter or data logger. A signal range of about 10mV to 20mV should be
available in order to prevent over range of the measured voltage signals. If the global broad-band solar
irradiance is measured continuously, it is recommended to use an accurate data logger with sufficient data
storage capacity and data manipulation functions. Some recommendations for setting up a continuous
measurement system are given in the following:
1) Measurement range settings:
If the measurement range can be selected on the data acquisition system, select the measurement
range which can accurately measure the signal over a range of 0 to 10mV. Under the assumption that
the global broad-band solar irradiance does not exceed 1,400W/m
2
(in both horizontal and tilted
measurement positions) the signal level of the pyranometer output Voltage will remain below 10mV. This
maximum output Voltage can be calculated by multiplying the maximum solar irradiance with the
calibration factor (e.g. when the sensitivity of the MS-802 pyranometer is about 7μV/W ・ m
-2
or
0.007mV/W・m
-2
, the maximum output voltage is about 1,400W/m
2
times 0.007mV/W・m
-2
= 10.5mV).
2) Calculate the global broad-band solar irradiance [W/m
2
].
The global solar irradiance in Watts per meter squared (W/m
2
) is obtained when the output voltage E [μV]
is divided by the sensitivity of the pyranometer S [μV/W・m
-2
]. This calculation is expressed by the
following formula:
I (W/m
2
) =
*The sensitivity S for the pyranometer is stated on the calibration certificate and the product label.
Sampling Rates and Averaging/Integrating of Measurement Data
In continuous operation mode the pyranometer is usually connected to a programmable data logger
system. Hence, sampling rates and data reduction methods can be defined right at the beginning of the
data acquisition process.
To explore the maximum measurement capacity of the pyranometer and in order to limit the data volume,
the sampling rate and the averaging/integrating period have to be chosen carefully. Choosing the right
sampling rate depends on the pyranometer’s response time. Note that the EKO pyranometer-series
have different response times, ranging from 5 seconds (MS-802) to 17 seconds (MS-602). The
response time that is given in the specifications of the EKO pyranometers states the amount of time
which is necessary to reach 95% of the final measurement value. It is also possible to define a 63.2%
response (which is equal to 1-1/e). This time constant, represented by the symbol τ, is 3 times smaller
than the values specified by EKO.
E (μV)
S (μV/W･m
-2
)

EKO MS-802 Specifications

General

Brand	EKO
Model	MS-802
Category	Measuring Instruments
Language	English