Fitting The Connector And Cable; Fitting The Sun Shield; Installation For Measurement Of Tilted Global Irradiance; Installation For Measurement Of Reflected Global Irradiance - Kipp & Zonen SMP series Instruction Manual

.

2.4.6 Fitting the connector and cable

Locate the plug correctly in the radiometer socket, it only fits one way, and push it in. Screw the plug locking ring hand-tight.
Over-tightening may damage the waterproof seal. Secure the cable so that it cannot blow in the wind or cause a shadow on the
instrument.
Note
The cable should be arranged with a curve below the instrument so that water drips o , rather than running along
the cable up to the connector.

2.4.7 Fitting the sun shield

Finally, clip on the sun shield to prevent excessive heating of the radiometer body. The bubble level is visible through the top
of the sun shield for routine checks and the shield 'tail' helps to protect the connector.

2.5 Installation for measurement of tilted global irradiance

When a pyranometer is mounted on a large flat tilted surface the temperature of this surface can rise considerably (more than
10 °C) above air temperature. It is advised to pre-adjust the levelling feet on a horizontal surface for easy mounting of the
instrument parallel to the inclined surface. It improves the measurement accuracy when the body is thermally isolated by its
feet from the surface. This promotes thermal equilibrium between the dome(s) and the housing and decreases zero o sets.
For accurately and securely fixing a pyranometer at an angle to a surface an adjustable tilt mounting kit is available. See Accessories
in chapter 3.
2.6 Installation for measurement of reflected global irradiance
In the inverted position the pyranometer measures reflected global radiation. The
height above the surface (H) depends upon its roughness. The WMO recommends a
height of 1 m to 2 m above a uniform surface covered by short grass.
The mounting device should not interfere significantly with the field of view of the
instrument. The mounting plate above the pyranometer prevents excessive heating of
the housing by downwards solar radiation and. The glare screen has an angle of 5 °
and is fitted to the pyranometer to prevent direct illumination of the domes by the sun
at sunrise and sunset. It is available as an accessory kit for all SMP's except the SMP3.
Thermal o set signals generated in the pyranometer are 5 times more significant
in the measurement of reflected radiation due to the lower irradiance level.
The mast shown intercepts a fraction D/2πS. of the radiation coming from the
ground. In the most unfavourable situation (sun at zenith) the pyranometer
shadow decreases the signal by a factor R2/H2.
As a guide, a black shadow below the pyranometer with a radius of 0.1 x H decreases the signal by 1 %, and 99 % of the signal
will originate from an area with a radius of 10 x H.
H
16
R S
Pyranometer
Lower screen (white)
Mast (black)
Equator
D