GHM Delta OHM LPPYRA11 User manual

Operating manual
Albedo
meter
LPPYRA
11
www.deltaohm.com
English
Keep for future reference.
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LPPYRA11 -2-V1.1
TABLE OF CONTENTS
1INTRODUCTION.................................................................................................... 3
2WORKING PRINCIPLE........................................................................................... 4
3INSTALLATION ..................................................................................................... 6
4ELECTRICAL CONNECTIONS.................................................................................. 8
5MEASUREMENT ..................................................................................................... 9
6MAINTENANCE.................................................................................................... 10
7TECHNICAL SPECIFICATIONS............................................................................. 11
8SAFETY INSTRUCTIONS...................................................................................... 12
9ORDERING CODES .............................................................................................. 13

LPPYRA11 -3-V1.1
1INTRODUCTION
The LPPYRA11 albedometer measures the net global radiation, as well as the albedo of
grounds (albedo is the ratio between diffuse radiation from a determined surface and
the quantity of radiation that arrives on the surface).
The LPPYRA11 is manufactured mounting two LPPYRA10 pyranometers in one housing
only. The upper pyranometer measures the incident radiation striking the ground [ ↓],
while the lower pyranometer measures the reflected radiation [ ↑].
The output signals of the two pyranometers can be processed to get the desired phys-
ical quantity.
The LPPYRA11 can be used as a pyranometer for measuring global radiation. As a py-
ranometer, the LPPYRA11 is a Spectrally Flat Class A (Secondary Standard) pyranom-
eter in accordance with ISO 9060:2018 and with the criteria of the WMO “Guide to
Meteorological Instruments and Methods of Observation”.
The albedometer is supplied factory calibrated and with a calibration report. The cali-
bration is carried out in accordance with the ISO 9847:1992 (type IIc) standard: ”Cal-
ibration of field pyranometers by comparison to a reference pyranometer”. The pyra-
nometer is calibrated by comparison with the reference sample calibrated annually at
WRC (World Radiation Center).

LPPYRA11 -4-V1.1
2WORKING PRINCIPLE
The LPPYRA11 albedometer is based on a pair of thermopile sensors, one of them
measuring the incident radiation on the ground [ ↓] and the other one the reflected
radiation [ ↑]. Each thermopile works as an independent pyranometer. The thermo-
pile sensitive surface is coated with a black matt paint, which allows the pyranometer
not to be selective at different wave lengths.
In order to grant the thermopile a proper thermal insulation from the wind and reduce
the sensitivity to thermal irradiance, LPPYRA11 is equipped with two concentric domes
having 50 mm and 32 mm outer diameter on each side. The domes protect the ther-
mopile from the dust, which might change spectral sensitivity if it lies on the black
surface.
The pyranometer spectral range is determined by the transmission of the two glass
domes. Thanks to the use of a new material for the manufacturing of the domes, the
spectral range has been further extended to short wavelengths starting from 283 nm.
Considering a standard solar spectrum, the portion of solar irradiation measured by
the pyranometer is greater than 99.8%. Figure 2.1 shows the relative spectral sensi-
tivity of the LPPYRA11 albedometer and a standard solar spectrum.
Fig. 2.1: LPPYRA11 albedometer relative spectral sensitivity (blue line) com-
pared with a standard solar spectrum (red line)
Radiant energy is absorbed by the thermopile black surface, thus creating a difference
of temperature between the center of the thermopile (hot junction) and the pyranom-
eter body (cold junction). Thanks to the Seebeck effect, the difference of temperature
between hot and cold junction is converted into a Difference of Potential.
A second thermopile, not accessible by light, is mounted inside the instrument. This
second thermopile, connected in anti-series with respect to the sensor exposed to
light, reduces the signals due to sudden temperature changes of the pyranometer
(thermal shocks).
In order to minimize sensitivity changes with temperature, LPPYRA11 is equipped with
a passive compensation circuit. The graph in figure 2.2 shows the typical variation of
sensitivity at different temperatures. The deviations are calculated from the sensitivity
measured at 20 °C.

LPPYRA11 -5-V1.1
Fig. 2.2: : percentage change of LPPYRA11 albedometer sensitivity in the
temperature range -20…50 °C compared to the sensitivity at 20 °C
To prevent internal condensation forming on the internal side of the dome under cer-
tain climatic conditions, silica gel tablets are inserted inside the pyranometer to ab-
sorb humidity.
Fig. 2.1: scheme of principle LPPYRA11
Thermopile
Surge
Protector
Connector
pins
Housing
To cable shield
Thermopile
Surge
Protector
Temperature (°C)
% change of sensitivity
Thermopile
Thermopile
Temperature
compensation

LPPYRA11 -6-V1.1
3INSTALLATION
Before installing the albedometer, refill the cartridge containing silica-gel crystals. Sili-
ca gel absorbs humidity in the dome chamber and prevents, in particular climatic con-
ditions, condensation on the internal walls of the domes and measurement alteration.
Do not touch the silica gel crystals with your hands while refilling the cartridge. Carry
out the following instructions in an environment as drier as possible:
1. Loosen the three screws that fix the white shade disk.
2. Unscrew the silica gel cartridge using a coin.
3. Remove the cartridge perforated cap.
4. Open the sachet containing silica gel (supplied with the pyranometer).
5. Fill the cartridge with the silica gel crystals.
6. Close the cartridge with its own cap, paying attention that the sealing O-ring be
properly positioned.
7. Screw the cartridge to the pyranometer body using a coin.
8. Check that the cartridge is screwed tightly (if not, silica gel life will be reduced).
9. Position the shade disk and screw it with the screws.
10. The albedometer is ready for use.
The figure below shows the operations necessary to fill the cartridge with the silica gel
crystals.
Fig. 3.1: filling the silica-gel cartridge
Silica-gel
cartridge
Perforated cap
Sealed sachet
of silica-gel crystals
Filling
Closing the cartridge

LPPYRA11 -7-V1.1
•Mount the albedometer 1 – 2 m above the ground. Grass should be kept at the
same height all the year long. In snowy regions, keep the instrument above the
blanket of snow so that the distance from the albedometer to the snow be constant.
•The albedometer must be mounted in an easy-to-reach location in order to clean
the dome regularly and carry out maintenance. At the same time, make sure that
no buildings, constructions, trees or obstructions exceed the horizontal plane where
the upper pyranometer lies. If this is not possible, select a site where obstructions
in the path of the sun from sunrise to sunset do not exceed 5 degrees of elevation.
N.B.: The presence of obstructions on the horizon line affects significantly
the measurement of direct irradiance.
•The pyranometer must be located far from any kind of obstruction, which might re-
flect sunlight (or sun shadow) onto the pyranometer itself.
•In compliance with ISO TR9901 standard and WMO recommendations, when the
pyranometer is used without the white shade disk, it must be positioned so that its
connector is pointed to the North Pole, if the instrument is used in the Northern
Hemisphere, and to the South Pole, if used in the Southern Hemisphere. In any
case, it is better to follow this suggestion even when the shade disk is applied.
•The mounting can be made using the rod provided with the instrument. In order to
allow an accurate horizontal positioning, the pyranometer is equipped with a level-
ling device. The mast height does not exceed the pyranometer plane to avoid
measurement errors caused by any reflection or shadow of the mast itself.
•It is preferably to thermally insulate the pyranometer from its mounting bracket
ensuring, at the same time, a good electrical contact to ground.
Fig. 3.2: fixing and dimensions
Connector
Levelling device
LPSP1
LPSP3

LPPYRA11 -8-V1.1
4ELECTRICAL CONNECTIONS
LPPYRA11 has a 8-pole connector and use the CPM12AA8... optional cables in UV
resistant PTFE, with 8-pole connector on one side and open wires on the other side.
The metallic housing of the albedometer should preferably be
grounded ( ) locally. In this case, do not connect the wire of the
cable corresponding to the housing to prevent ground loops.
Only if it is not possible to ground locally the metallic case of the
albedometer, connect the wire of the cable corresponding to the
housing to ground ( ).
The albedometer LPPYRA11 is passive and does not require power supply. It is to be
connected either to a millivoltmeter or to a data acquisition system (with at least two
inputs). Typically, the albedometer output signal does not exceed 20 mV. In order to
better exploit the albedometer features, the readout instrument should have 1 µV res-
olution.
Connector Function Color
1
Output positive (+Vout) upper pyranometer [↓]
Red
2
Output negative (-Vout) upper pyranometer [↓]
Blue
3
Not connected
4
Not connected
5
Output negative (-Vout) lower pyranometer [↑]
Brown
6
Housing
White
7 Cable shield Black
8 Output positive (+Vout) lower pyranometer [
↑
] Green
Fig. 4.1: LPPYRA11 connections
The cable shield is isolated from the albedometer housing by means of two gas surge
arrestors, which prevents lightnings to damage the sensor. The shield has to be con-
nected to the same ground as the readout instrument. Best safety is achieved through
a perfect connection between housing and earth.
Connect to ground only if it is not possible to
ground locally the case of the pyranometer
CPM12AA8… cable
Sensor
male connector
Red [D]
Reflected
r
adiation [
↑
]
Incident
radiation
[
↓
]
Multi-
input
data
logger
Converter
amplifier
with VormA
output
Converter
amplifier
with VormA
output
or
or
Green [A]
Brown [F]
Blue [C]
Black [E]
White [B]

LPPYRA11 -9-V1.1
5MEASUREMENT
Each of the two pyranometer that make up the albedometer is distinguished by its
own sensitivity (or calibration factor) S expressed in µV/(Wm-2) and shown in the label
on the pyranometer (and in the calibration report).
The irradiance Eeis obtained by measuring with a multimeter the difference of potential
DDP at the ends of the sensor and applying the following formula:
Ee= DDP / S
where:
Eeis the irradiance expressed in W/m2;
DDP is the difference of potential expressed in µV measured by the multimeter;
Sis the sensitivity of the albedometer expressed in µV/(Wm-2).
Albedo is the fraction of solar radiation that is reflected from the ground, with respect
to incident radiation:
ALBEDO = Ee[↑] / Ee[↓]
With the albedometer it is possible to calculate the net radiation making the difference
between the incident global radiation and the reflected global radiation.

LPPYRA11 -10 -V1.1
6MAINTENANCE
In order to grant measurements high accuracy, it is important to keep the outer glass
domes clean. Consequently, the more the domes will be kept clean, the more meas-
urements will be accurate.
You can wash it using water and standard papers for lens. If necessary, use pure
ETHYL alcohol. After using alcohol, clean again the domes with water only.
Because of the high temperature changes between day and night, some condensation
might appear on the domes of the pyranometers. In this case the performed reading
is highly over-estimated. To minimize the condensation, the albedometer is provided
with a cartridge containing dessicant material (silica-gel). The efficiency of the silica-
gel crystals decreases over time while absorbing humidity. Silica-gel crystals are effi-
cient when their color is yellow, while they turn white/translucent as soon as they
loose their efficiency. Read instructions at chapter 3 about how to replace the silica-
gel crystals. Silica-gel typical lifetime goes from 2 to 6 months depending on the envi-
ronment where the albedometer works.
To exploit all the albedometer features, it is highly recommended that the calibration
be checked annually.

LPPYRA11 -11 -V1.1
7TECHNICAL SPECIFICATIONS
Sensor Thermopile
Typical sensitivity 6÷11 µV/Wm-2
Impedance 5÷50 Ω
Measuring range 0÷4000 W/m2
Viewing angle 2πsr
Spectral range (50%) 283÷2800 nm
Operating temperature/humidity -40÷80 °C / 0÷100%
Output Analog in µV/Wm-2
Connection 8-pole M12 connector
Dimensions Fig. 3.2
Weight 1.35 kg (complete albedometer)
Accuracy of levelling device < 0.1°
Protection degree IP 67
MTBF > 10 years
Technical Specifications According to ISO 9060
Response time (95%) < 5 s
Zero offset
a) response to a 200 W/m2thermal
radiation < 7 W/m2
b) response to a 5 K/h change in
ambiente temperature <±2W/m2
Long-term instability (1 year) <±0.5%
Non-linearity <±0.2%
Response according to the cosine law <±10W/m2
Spectral selectivity < ±3%
Temperature response (-10…+40°C) < 1 %
Tilt response <±0.2%
The technical specifications are the same for both pyranometers that make up the albedometer.
Thus here are the specifications related to a single sensor (except the weight).

LPPYRA11 -12 -V1.1
8SAFETY INSTRUCTIONS
General safety instructions
The instrument has been manufactured and tested in accordance with the safety
standard EN61010-1:2010 “Safety requirements for electrical equipment for meas-
urement, control and laboratory use” and has left the factory in perfect safety tech-
nical conditions.
The instrument proper operation and operating safety can be ensured only if all
standard safety measures as well as the specific measures described in this manual
are followed.
The instrument proper operation and operating safety can be ensured only in the cli-
matic conditions specified in this manual.
Do not use the instruments in places where there are:
•Corrosive or flammable gases.
•Direct vibrations or shocks to the instrument.
•High-intensity electromagnetic fields, static electricity.
User obligations
The instrument operator shall follow the directives and regulations below that refer to
the treatment of dangerous materials:
•EEC directives on workplace safety.
•National law regulations on workplace safety.
•Accident prevention regulations.

LPPYRA11 -13 -V1.1
9ORDERING CODES
LPPYRA11 Albedometer made up of two Spectrally Flat Class A (Secondary
Standard) pyranometers according to ISO 9060:2018. Supplied
with: top and bottom shade disks, cartridge for silica-gel crystals,
2 recharges, levelling device, Ø16x500 mm fixing rod, M12 8-pole
connector and Calibration Report. CPM12AA8… cable has to be
ordered separately.
LPSP1 UV-resistant shade disk for the upper pyranometer (spare part).
LPSP3 UV-resistant shade disk for the lower pyranometer (spare part).
CPM12AA8.2 Cable with 8-pole M12 connector on one end, open wires on the
other end. Length 2 m.
CPM12AA8.5 Cable with 8-pole M12 connector on one end, open wires on the
other end. Length 5 m.
CPM12AA8.10 Cable with 8-pole M12 connector on one end, open wires on the
other end. Length 10 m.
LPSG Cartridge to contain desiccant silica-gel crystals, complete with O-
ring and cap.
LPG Pack of 5 sachets of silica-gel crystals.
DELTA OHM metrology laboratories LAT N° 124 are ISO/IEC 17025 accredited by
ACCREDIA for Temperature, Humidity, Pressure, Photometry / Radiometry, Acous-
tics and Air Velocity. They can supply calibration certificates for the accredited
quantities.

LPPYRA11 -14 -V1.1
NOTES

GUARANTEE
TERMS OF GUARANTEE
All DELTA OHM instruments are subject to accurate testing, and are guaranteed for 24 months from the
date of purchase. DELTA OHM will repair or replace free of charge the parts that, within the warranty
period, shall be deemed non efficient according to its own judgement. Complete replacement is excluded
and no damage claims are accepted. The DELTA OHM guarantee only covers instrument repair. The
guarantee is void in case of incidental breakage during transport, negligence, misuse, connection to a
different voltage than that required for the appliance by the operator. Finally, a product repaired or
tampered by unauthorized third parties is excluded from the guarantee. The instrument shall be returned
FREE OF SHIPMENT CHARGES to your dealer. The jurisdiction of Padua applies in any dispute.
The electrical and electronic equipment marked with this symbol cannot be disposed of in public
landfills. According to the Directive 2011/65/EU, the european users of electrical and electronic
equipment can return it to the dealer or manufacturer upon purchase of a new one. The illegal
disposal of electrical and electronic equipment is punished with an administrative fine.
This guarantee must be sent together with the instrument to our service centre.
IMPORTANT: Guarantee is valid only if coupon has been correctly filled in all details.
Instrument Code:
LPPYRA11
Serial Number
RENEWALS
Date
Date
Inspector
Inspector
Date
Date
Inspector
Inspector
Date
Date
Inspector
Inspector

GHM GROUP – Delta OHM | Delta Ohm S.r.l. a socio unico
Via Marconi 5 | 35030 Caselle di Selvazzano | Padova | ITALY
Phone [phone] | Fax [phone]
www.deltaohm.com | [e-mail]
The quality level of our instruments is the result of the constant development of the product. This may
produce some differences between the information written in this manual and the instrument you have
purchased. We cannot completely exclude the possibility of errors in the manual, for which we apologize.
The data, images and descriptions included in this manual cannot be legally asserted. We reserve the
right to make changes and corrections with no prior notice.

GHM GROUP – Delta OHM | Delta Ohm S.r.l. a socio unico
Via Marconi 5 | 35030 Caselle di Selvazzano | Padova | ITALY
Phone [phone] | Fax [phone]
www.deltaohm.com | [e-mail]
V1.1
04/12/2019