Hukseflux DR01 User manual

Copyright by Hukseflux | manual v1609 | www.huksefluxusa.com | [email protected]
USER MANUAL DR-SERIES
PYRHELIOMETERS
First class pyrheliometer DR01
Fast response first class pyrheliometer DR02
Compact fast response first class pyrheliometer DR03

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Warning statements
Putting more than 12 Volt across the sensor wiring
can lead to permanent damage to the sensor.
Do not use “open circuit detection”when measuring
the sensor output.

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Contents
Warning statements 2
Contents 3
List of symbols 4
Introduction 5
1Ordering and checking at delivery 7
1.1 Ordering DR01, DR02 and DR03 7
1.2 Included items 7
1.3 Quick instrument check 8
2Instrument principle and theory 9
3Specifications of DR01 / DR02 / DR03 11
3.1 Specifications 11
3.2 Dimensions of DR01 & DR02 15
4Standards and recommended practices for use 16
4.1 Classification standard 16
4.2 General use for solar radiation measurement 16
4.3 General use for sunshine duration measurement 17
4.4 Specific use in meteorology and climatology 17
5Installation of pyrheliometers 18
5.1 Site selection and installation 18
5.2 Installation of the protection cap 18
5.3 Electrical connection 19
5.4 Requirements for data acquisition / amplification 20
6Making a dependable measurement 21
6.1 The concept of dependability 21
6.2 Reliability of the measurement 22
6.3 Speed of repair and maintenance 23
6.4 Uncertainty evaluation 23
7Maintenance and trouble shooting 28
7.1 Recommended maintenance and quality assurance 28
7.2 Trouble shooting 29
7.3 Calibration and checks in the field 30
7.4 Data quality assurance 30
8DR03 31
8.1 Introduction DR03 31
8.2 Dimensions of DR03 32
9Appendices 34
9.1 Appendix on cable extension / replacement 34
9.2 Appendix on optional chassis connector & cable connector 35
9.3 Appendix on tools for DR01 / DR02 / DR03 35
9.4 Appendix on spare parts for DR01 / DR02/ DR03 35
9.5 Appendix on standards for classification and calibration 36
9.6 Appendix on calibration hierarchy 37
9.7 Appendix on requirements for solar tracking 38
9.8 Appendix on meteorological radiation quantities 39
9.9 Appendix on ISO and WMO classification tables 40
9.10 Appendix on definition of pyrheliometer specifications 42
9.11 Appendix on terminology / glossary 43
9.12 Appendix on literature references 45
9.13 EC declaration of conformity 46

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List of symbols
Quantities Symbol Unit
Voltage output U V
Sensitivity S V/(W/m2)
Solar irradiance E W/m2
(see also appendix 9.8 on meteorological quantities)
Subscripts
Not applicable

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Introduction
DR01, DR02 and DR03 are high-accuracy direct normal irradiance (DNI) solar radiation
sensors, also known as pyrheliometers. The DR-series pyrheliometers comply with the
‘first class’ specifications of the ISO 9060 standard and the ‘good quality’ performance
level of WMO’s No. 8 Guide. Pyrheliometers are typically mounted on a solar tracker.
A unique product feature of all pyrheliometers in the DR-series is the heated window.
DR02 and DR03 are the fast-response versions of DR01. The difference is in detector
technology, resulting in a much faster response time (95 %) for DR02 and DR03: 2 s
instead of the traditional 12 s. DR02 has the same body and dimensions as DR01. DR03
is a compact version of DR02 pyrheliometer.
This manual is written for the standard model DR01; DR02 and DR03
specifications and operation are mentioned only in case these differ from
DR01’s. DR03, with its different dimensions, has a dedicated chapter in this
manual.
Figure 0.1 DR01 /DR02 pyrheliometer Figure 0.2 DR03 pyrheliometer
DR01 is a solar radiation sensor that is applied in high accuracy observations. It
measures the solar radiation received by a plane surface from a 5 ° full field of view
angle. This quantity, expressed in W/m2, is called ‘direct’ solar radiation or direct normal
irradiance (DNI). Pyrheliometers are generally employed outdoors under the sun. It is
necessary to keep the instrument pointed at the sun by using a two-axis tracker. Typical
DR01 applications include solar energy resource assessment, system performance
monitoring (in particular for concentrated solar energy) and scientific solar climate
observations.
DR01 pyrheliometer features a precision ground and polished quartz window, a
collimated tube and a thermopile sensor with black coated surface. It has an anodised

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aluminium body. DR01 also features a thermally isolated low-power heater in the window
assembly. The heater increases data availability, for instance by reducing measurement
errors caused by (early-morning) dew deposition. DR01 pyrheliometer is optionally
equipped with a temperature sensor and is optionally characterised for its temperature
response. This can be used to increase the accuracy of the measurement.
Using DR01 is easy. It can be connected directly to commonly used data logging
systems. The irradiance, E, in W/m2is calculated by dividing the DR01 output, a small
voltage U, by the sensitivity S. The sensitivity is provided with DR01 on its calibration
certificate.
The central equation governing DR01 is:
E = U/S (Formula 0.1)
A pyrheliometer can also be used to measure sunshine duration. Sunshine duration
during a given period is defined as the sum of that sub-period for which the direct solar
irradiance exceeds 120 W/m2.
Suggested use for DR01:
outdoor PV / CPV and CSP system performance monitoring
solar energy surveys
solar resource assessments
meteorological networks
Applicable instrument classification standards are ISO 9060 and WMO-No. 8. Calibration
is traceable to WRR (World Radiometric Reference).
The instrument should be used in accordance with the recommended practices of ISO,
WMO and ASTM.
Various tracking solutions can be offered by Hukseflux. Please contact us for more
information on solar trackers.
Figure 0.3 Applications of DR01, DR02 and DR03 pyrheliometers, combined with SR20
pyranometers, in typical solar radiation monitoring stations

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1Ordering and checking at delivery
1.1 Ordering DR01, DR02 and DR03
The standard configuration of DR01 is with 5 metres cable.
Common options are:
Longer cable in multiples of 5 m, cable lengths above 20 m in multiples of 10 m.
Specify total cable length.
Internal temperature sensor. This can be either a Pt100 or a 10 kΩ thermistor.
Specify respectively T1 or T2.
Five silica gel bags in an air-thight bag for desiccant holder. Specify part number
DC01.
Temperature dependence characterisation
Improved temperature response
Standard DR01 / DR02 / DR03 pyrheliometers are equipped with a cable with cable
gland. Optionally the instrument may be ordered with a chassis connector and a cable
with connector. Please consult Hukseflux.
1.2 Included items
Arriving at the customer, the delivery should include:
pyrheliometer DR01 / DR02 / DR03
cable of the length as ordered
product certificate matching the instrument serial number
any other options as ordered
Please store the certificate in a safe place.

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1.3 Quick instrument check
A quick test of the instrument can be done by using a simple hand held multimeter and a
lamp.
1. Check the electrical resistance of the sensor between the green (-) and white (+) wire.
See chapter 5.3 on electrical connections. Use a multimeter at the 1000 Ω range.
Measure the sensor resistance first with one polarity, than reverse the polarity. Take the
average value. The typical resistance of the wiring is 0.1 Ω/m. Typical resistance should
be the typical sensor resistance of 400 to 500 Ω for DR01 and 150 to 250 Ω for DR02
and DR03, plus 1.5 Ω for the total resistance of two wires (back and forth) of each 5 m.
Infinite resistance indicates a broken circuit; zero or a low resistance indicates a short
circuit.
2. Check if the sensor reacts to light: put the multimeter at its most sensitive range of
DC voltage measurement, typically the 100 x 10-3 VDC range or lower. Expose the sensor
to a strong light source, for instance a 100 W light bulb at the front window. The signal
should read > 2 x 10-3 V now. Darken the sensor either by putting something over it or
switching off the light. The instrument voltage output should go down and within one
minute approach 0 V.
3. Inspect the instrument for any damage. Check if the sight is straight and aligned.
4. Inspect if the humidity indicator is blue. The colour pink indicates it is not dry but
humid: in the latter case replace the desiccant (see chapter on maintenance).
5. Optional: inspect the electrical resistance range of the internal temperature sensors
(for Pt100 in the 100 Ω range, for 10 kΩ thermistors in the 10 000 Ω range, in case of 3
wire or 4 wire connections of the Pt100 in the < 10 Ω range between connections at one
end).
Figure 1.3.1 DR01 first class pyrheliometer

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2Instrument principle and theory
Figure 2.1 Overview of DR01:
(1) humidity indicator
(2) sights
(3) aperture tube
(4) protection cap
(5) window assembly with heater
(6) cable gland
(7) cable (standard length 5 metres cable, optional longer cable)
DR01’s scientific name is pyrheliometer. It measures the solar radiation received by a
plane surface from a 5 ° full field of view angle. In addition to the full field of view angle,
(the angle from the centre of the sensor to the edge of the aperture window) WMO
recommends in WMO manual 7.2 a slope angle (the angle from the side of the sensor to
the edge of the window aperture) of 1 °. The opening angle and slope angle together
with the sensor surface define the so-called acceptance function (see appendix on
terminology).
A pyrheliometer should measure ‘direct’ solar radiation, also called direct normal
irradiance or DNI. DNI is defined as the solar radiant flux collected by a plane unit
surface normal to the axis pointing towards the centre of the sun, within an optical
angular aperture. This aperture is characterized by the acceptance function (ref: IEA SHC
#46 and EU FP7 MACC-II projects, published by Blanc et al. (2014), see appendix on
terminology and appendix on literature references).
DNI is composed of the solar irradiance within the extent of the solar disk (half-angle
0.266 ° ± 1.7 %) plus some circumsolar radiation.
1
2
3
24
5
6
7

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Summarising, DR01 is a radiometer designed to measure DNI (i.e. including some
circumsolar irradiance). It complies with the WMO recommended parameters for the
view-limiting geometry: a full opening angle of 5 °, and a slope angle of 1 °, and
therefore a limit angle of 4 °.
The solar radiation spectrum extends roughly from 285 to 3000 x 10-9 m. By definition a
pyrheliometer should cover that spectral range with a spectral selectivity that is as “flat”
as possible.
For a correct measurement DR01 should be pointed at the sun. It is usually mounted on
a solar tracker. For tracking requirements see the appendix on solar tracking.
In order to attain the proper directional and spectral characteristics, DR01
pyrheliometer’s main components are:
a thermal sensor with black coating. It has a flat spectrum covering the 200 to 4000
x 10-9 m range. The coating absorbs all solar radiation and, at the moment of
absorption, converts it to heat. The heat flows through the sensor to the instrument
body. The thermopile sensor generates a voltage output signal that is proportional to
the solar irradiance.
a quartz glass window. This window limits the spectral range from 200 to 4000 x 10-9
m (cutting off the part above 4000 x 10-9 m)
an aperture tube. The most important components of this tube are two apertures.
One at the detector and the other at the front window. These determine the opening-
and slope angle.
A heater incorporated in the window assembly. This reduces measurement errors
caused by (early-morning) dew deposition. Typically the heater is switched on at
night only. Some users have employed the heater in high-power operation to counter
frost deposition.
Pyrheliometers can be manufactured to different specifications and with different levels
of verification and characterisation during production. The ISO 9060 - 1990 standard,
“Solar energy - specification and classification of instruments for measuring
hemispherical solar and direct solar radiation”, distinguishes between 3 classes;
secondary standard (highest accuracy), first class (second highest accuracy) and second
class (third highest accuracy).
Due to the required spectral selectivity a secondary standard pyrheliometer can only be
made with a cavity-type sensor. In addition the calibration of a secondary standard
pyrheliometer must be done by periodic comparison with a primary standard radiometer.
For this reason commercially available thermopile pyrheliometers with a flat detector and
a window can only be first-class.
From first class to secondary standard, the achievable accuracy improves by a factor 2.

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3Specifications of DR01 / DR02 / DR03
3.1 Specifications
DR01 measures the solar radiation received by a plane surface from a from a 5 ° full field
of view angle and a 1 ° slope angle, i.e. the acceptance function recommended by WMO.
This quantity, expressed in W/m2, is called ‘direct’ solar radiation or direct normal
irradiance (DNI). DNI can be used to calculate sunshine duration. Working completely
passive, using a thermopile sensor, DR01 generates a small output voltage proportional
to this flux. It can only be used in combination with a suitable measurement system and
a solar tracker to keep it continuously aimed at the sun. The window assembly contains a
heater which may be activated to prevent dew deposition. The instrument is classified
according to ISO 9060 and should be used in accordance with the recommended
practices of ISO, IEC, WMO and ASTM.
DR02 and DR03 are fast-response versions of DR01. DR03 is a compact version of DR02.
Table 3.1.1 Specifications of DR01 / DR02 / DR03 (continued on next pages)
DR01 / DR02 / DR03 MEASUREMENT SPECIFICTIONS:
LIST OF CLASSIFICATION CRITERIA OF ISO 9060*
ISO classification (ISO 9060: 1990)
first class pyrheliometer
WMO performance level (WMO-No-8,
seventh edition 2008)
good quality pyrheliometer
Response time (95 %)
DR01: 12 s (nominal)
DR02: 2 s (nominal)
DR03: 2 s (nominal)
Zero offset (response to 5 K/h
change in ambient temperature)
< ± 1 W/m2
Non-stability
< ± 0.5 % change per year
Non-Linearity
< ± 0.3 % (100 to 1000 W/m2)
Full field of view angle
5 °
Slope angle
1 °
Limit angle
4 ° (follows from full field of view angle and slope angle)
Spectral selectivity
< ± 1 % (0.35 to 1.5 x 10-6 m)
Temperature response
< ± 1 % (-10 to +40 °C)
< ± 0.4 % (-30 to +50 °C)**
** with correction in dataprocessing if opted for internal
temperature sensor + temperature dependence
characterisation (see options)
Tilt response
< ± 0.5 % (0 to 90 ° at 1000 W/m2)
*For the exact definition of pyrheliometer ISO 9060 specifications see the appendix.

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Table 3.1.1 Specifications of DR01 / DR02 / DR03 (continued)
ADDITIONAL SPECIFICATIONS
Measurand
direct solar radiation
with the acceptance function recommended by WMO
Measurand in SI radiometry units
irradiance in W/m2
Optional measurand
sunshine duration
Measurement range
0 to 4000 W/m-2
Spectral range (50 % transmission
points)
200 to 4000 x 10-9 m
Sensitivity range
7 to 15 x 10-6 V/(W/m2)
Sensitivity (nominal)
10 x 10-6 V/(W/m2)
Rated operating temperature range
-40 to +80 °C
Rated operating relative humidity range
0 to 100 %
Sensor resistance range
DR01: 400 to 500 Ω
DR02: 150 to 250 Ω
DR03: 150 to 250 Ω
Required sensor power
zero (passive sensor)
see also heated window assembly
Expected voltage output
application under natural solar radiation: -0.1 to + 30
x 10-6 V
Measurement function / required
programming
E = U/S
Optional measurement function /
required programming for correction of
sensitivity as a function of instrument
body temperature
E = U/(S0·(a·T²+b·T+c))
Measurement function / required
programming for sunshine duration
if E > 120 W/m2then SD = 1 else SD = 0
Required readout
1 differential voltage channel or 1 single ended
voltage channel, input resistance > 106Ω
Optional readout
1 temperature channel in case optional temperature
sensor is present and used
Standards governing use of the
instrument
- WMO-No. 8; Guide to Meteorological Instruments
and Methods of Observation, chapter 7, measurement
of radiation, 7.2 measurement of direct solar radiation
- ASTM G183 - 05 Standard Practice for Field Use of
Pyranometers, Pyrheliometers and UV Radiometers
- WCRP - 121, WMO/TD-No. 1274:
BSRN operations manual version 2.1-2005
- WMO-No. 8; Guide to Meteorological Instruments
and Methods of Observation, chapter 8, measurement
of sunshine duration, 8.2.1 pyrheliometric method
Total sensor length including cap
DR01: 380 x10-3 m
DR02: 380 x10-3 m
DR03: 286 x10-3 m
Standard cable length (see options)
5 m
Cable diameter
5.3 x 10-3 m
Cable gland: cable diameter range
accepts cable diameters from 2.5 to 6.5 x 10-3 m
Cable replacement
cable can be removed and installed by the user
provided that the cable is sealed at the sensor side
against humidity ingress. Consult Hukseflux for
instructions or use Hukseflux-supplied parts
Mounting
DR01, DR02, DR03: mounting with 2 clamps around
the pyrheliometer tube Ø 38 x 10-3 m,
DR01, DR02: clamp to clamp distance of 214 x 10-3 m
max.
DR03: clamp to clamp distance of 120 x 10-3 m max.
.
.

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Table 3.1.1 Specifications of DR01 / DR02 / DR03 (continued)
IP protection class
IP67
Desiccant
Two bags of silica gel, 0.5 g, (35 x 20) x 10-3 m
Recommended desiccant replacement
interval
2 years
(typically at the moment of calibration)
Humidity indicator
blue when dry, pink when humid
SHIPPING
Gross weight including 5 m cable
1.0 kg
Net weight including 5 m cable
DR01: 0.9 kg
DR02: 0.9 kg
DR03: 0.8 kg
Packaging
box of (430x105x105) x 10-3 m
TRACKING AND ALIGNMENT
Required tracking
the instrument must be pointed at the sun centre
Required alignment
the pyrheliometer and the tracker should be aligned
using the pyrheliometer sight
Rated misalignment interval
(without impact on measurement
accuracy)
DR01: ± 0.5 °
DR02: ± 0.5 °
DR03: ± 0.3 °
from the sun centre, using the pyrheliometer sight as
a reference
Sight resolution
DR01: < 0.2 °
DR02: < 0.2 °
DR03: < 0.4 °
lightspot projection < 25 % off target hole
Sight sensitivity
DR01: 4 x 10-3 m/°
DR02: 4 x 10-3 m/°
DR03: 2 x 10-3 m/°
WINDOW ASSEMBLY WITH HEATER
Window assembly with heater
12 VDC, 0.5 W
Heater operation
the heater is not necessarily switched on;
recommended operation is to activate the heater
when the sun is below the horizon
Heater resistance
272 Ω
Steady state zero offset caused by 0.5W
heating
< 1 W/m2
Optional high power operation of the
heater to rapidly remove frost
24 VDC, 2 W
Steady state zero offset caused by high
power 2 W heating
< 4 W/m2
CALIBRATION
Calibration traceability
to WRR
Calibration hierarchy
from WRR through ISO 9059, applying a correction to
reference conditions
Calibration method
indoor comparison to a reference pyrheliometer
Calibration uncertainty
< 1.2 % (k = 2)
Recommended recalibration interval
2 years
Reference conditions
20 °C, horizontal mounting , irradiance level 1000
W/m2
Validity of calibration
based on experience the instrument sensitivity will not
change during storage. During use under exposure to
solar radiation the instrument “non-stability”
specification is applicable.

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Table 3.1.1 Specifications of DR01/DR02/DR03 (started on previous pages)
MEASUREMENT ACCURACY
Uncertainty of the measurement
statements about the overall measurement
uncertainty can only be made on an individual basis.
See the chapter on uncertainty evaluation
WMO ESTIMATE OF ACHIEVABLE MEASUREMENT UNCERTAINTY
Minute totals
± 1.8 % (k = 2)
(under typical conditions, well maintained, not taking
calibration uncertainty into account)
Hourly totals
± 1.5 % (k = 2)
(under typical conditions, well maintained, not taking
calibration uncertainty into account)
Daily totals
± 1.0 % (k = 2)
(under typical conditions, well maintained, not taking
calibration uncertainty into account)
VERSIONS / OPTIONS
Internal temperature sensor
measuring the body temperature:
version code = T1 for Pt100 DIN class A,
version code = T2 for thermistor 10 kΩ at 25 °C
longer cable, in multiples of 5 m, cable
lengths above 20 m in multiples of 10 m
option code = total cable length
Temperature dependence
characterisation
option code = TRC
< ± 1 % (-10 to +40 °C)
< ± 0.4 % (-30 to +50 °C) with correction in
dataprocessing
Improved temperature response
includes TRC
option code = ITR
< ± 0.5 % (-20 to +50 °C)
< ± 0.4 % (-30 to +50 °C) with correction in
dataprocessing
Adapted sensitivity range
DR01 only: the sensitivity range can be adapted to
customer requirements (to a lower range only)
option code = lower end - higher end of the allowed
range x 10-6 V/(W/m2)
Chassis connector and cable with
connector
M16 panel connector, male thread, 10-pole
Cable with M16 straight connector, female thread, 10-
pole
option code = C
ACCESSORIES
Protection cap
spare protection cap
Bags of silica gel for desiccant
set of 5 bags in an air tight bag
option code = DC01

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3.2 Dimensions of DR01 & DR02
Figure 3.2.1 Dimensions of DR01 and DR02 in x 10-3 m. For DR03 dimensions see the
dedicated chapter on DR03.
380
215
50
Ø 38

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4Standards and recommended practices
for use
Pyrheliometers are classified according to the ISO 9060 standard and the WMO-No. 8
Guide to Meteorological Instruments and Methods of Observation. In any application the
instrument should be used in accordance with the recommended practices of ISO, IEC,
WMO and / or ASTM.
4.1 Classification standard
Table 4.1.1 Standards for pyrheliometer classification. See the appendix for definitions
of pyrheliometer specifications, and a table listing the specification limits.
STANDARDS FOR INSTRUMENT CLASSIFICATION
ISO STANDARD
EQUIVALENT
ASTM STANDARD
WMO
ISO 9060:1990
Solar energy -- specification and
classification of instruments for
measuring hemispherical solar and
direct solar radiation
Not available
WMO-No. 8; Guide to
Meteorological Instruments
and Methods of Observation,
chapter 7, measurement of
radiation, 7.2 measurement
of direct solar radiation
4.2 General use for solar radiation measurement
Table 4.2.1 Standards with recommendations for instrument use in solar radiation
measurement
STANDARDS FOR INSTRUMENT USE FOR DIRECT SOLAR RADIATION
ISO STANDARD
EQUIVALENT
ASTM STANDARD
WMO
Not applicable
ASTM G183 - 05
Standard Practice for Field
Use of Pyranometers,
Pyrheliometers and UV
Radiometers
WMO-No. 8; Guide to
Meteorological Instruments
and Methods of Observation,
chapter 7, measurement of
radiation, 7.2 measurement
of direct solar radiation
WCRP - 121, WMO/TD-No.
1274: BSRN operations
manual version 2.1-2005

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4.3 General use for sunshine duration measurement
According to the World Meteorological Organization (WMO, 2003), sunshine duration
during a given period is defined as the sum of that sub-period for which the direct solar
irradiance exceeds 120 W/m2.
WMO has approved the “pyrheliometric method” to estimate sunshine duration from
pyrheliometer measurements (Chapter 8 of the WMO Guide to Instruments and
Observation, 2008). This implies that pyrheliometers may be used, in combination with
appropriate software to determine the threshold of 120 W/m2, to measure sunshine
duration.
Table 4.3.1 Standards with recommendations for instrument use in sunshine duration
measurement
STANDARDS FOR INSTRUMENT USE FOR SUNSHINE DURATION
WMO
WMO-No. 8; Guide to Meteorological Instruments and Methods of Observation, chapter 8,
measurement of sunshine duration, 8.2.1 Pyrheliometric Method
4.4 Specific use in meteorology and climatology
The World Meteorological Organization (WMO) is a specialised agency of the United
Nations. It is the UN system's authoritative voice on the state and behaviour of the
earth's atmosphere and climate. WMO publishes WMO-No. 8; Guide to Meteorological
Instruments and Methods of Observation, in which a table is included on “level of
performance” of pyrheliometers. Nowadays WMO conforms itself to the ISO classification
system.

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5Installation of pyrheliometers
5.1 Site selection and installation
Table 5.1.1 Recommendations for installation of pyrheliometers
Location
The horizon should be as free from obstacles as
possible. Ideally there should be no objects between
the course of the sun and the instrument
Mechanical mounting / thermal insulation
preferably use the tube for clamping the instrument. A
pyrheliometer is sensitive to thermal shocks. Do not
mount the instrument on objects that become very
hot (black coated metal plates).
Performing a representative
measurement
the pyrheliometer measures the solar radiation in a
limited field of view. A representative measurement
requires that the instrument is accuractely pointing
towards the sun centre. A maximum deviation of
better than 0.75 ° is allowed (for DR01 and DR02 ±
0.5 ° relative to the pyrheliometer sight alignment, for
DR03 ± 0.3 ° ) before it results in measurement
errors.
Use the sight of the pyrheliometer as a reference.
See the chapter on uncertainty evaluation.
5.2 Installation of the protection cap
The protection cap can be installed and removed using a hex key (size 2.5 x 10-3 m).

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5.3 Electrical connection
In order to operate, a pyrheliometer should be connected to a measurement system,
typically a so-called datalogger. DR01 employs a passive sensor that does not need any
power. In case the heater is used, it consumes 1.5 W at 12 VDC.
Cables generally act as a source of distortion, by picking up capacitive noise. We
recommend keeping the distance between a datalogger or amplifier and the sensor as
short as possible. For cable extension, see the appendix on this subject.
The wiring electrical connection of your instrument can be found on its product
certificate.
Table 5.3.1 The electrical connection of DR01. In the standard DR01, only the signal and
heater wires are used. The table also shows connection of optional versions T1 and T2.
The heater is not necessarily used. The temperature sensor is not necessarily used.
PIN
WIRE
DR01
DR01-T1
DR01-T2
1
Red
Pt100 [+]
10 kΩ thermistor [+]
2
Brown
Pt100 [+]
10 kΩ thermistor [+]
3
Yellow
Pt100 [−]
10 kΩ thermistor [−]
4
Blue
Pt100 [−]
10 kΩ thermistor [−]
5
Pink
heater
heater
heater
6
Grey
heater
heater
heater
7
Green
signal [−]
signal [−]
signal [−]
8
White
signal [+]
signal [+]
signal [+]
9
Black
ground
ground
ground
Note 1: Pt100’s of optional version T1 may be connected in a 3-wire or 4-wire
configuration.
Note 2: 10 kΩthermistors of optional version T2 are usually connected in a 2-wire
configuration.
Note 3: the heater is not necessarily connected. In case it is connected, the polarity of
the connection is not significant.
Note 4: signal wires are insulated from ground wire and from the sensor body. Insulation
resistance is tested during production and larger than 1 x 106Ω.
Note 5: Ground is connected to the instrument body and the shield of the cable.

DR01 DR02 DR03 manual v1609 20/47
Figure 5.3.2 Electrical diagram showing the internal wiring of DR01 and options with
body temperature measurement. The shield is connected to the instrument body.
5.4 Requirements for data acquisition / amplification
The selection and programming of dataloggers is the responsibility of the user. Please
contact the supplier of the data acquisition and amplification equipment to see if
directions for use with the DR01 are available. In case programming for similar
instruments is available, this can typically also be used. The irradiance signal of DR01
can usually be treated in the same way as other thermopile pyrheliometers and
pyranometers. Pyrheliometers usually have the same programming as heat flux sensors.
Table 5.4.1 Requirements for data acquisition and amplification equipment for DR01 in
the standard configuration
Capability to measure small voltage
signals
preferably: 5 x 10-6 V uncertainty
Minimum requirement: < 20 x 10-6 V uncertainty
(valid for the entire expected temperature range of the
acquisition / amplification equipment)
Capability for the data logger or the
software
to store data, and to perform division by the sensitivity to
calculate the solar irradiance.
E = U/S (Formula 0.1)
Data acquisition input resistance
> 1 x 106Ω
Open circuit detection
(WARNING)
open-circuit detection should not be used, unless this is done
separately from the normal measurement by more than 5
times the sensor response time and with a small current
only. Thermopile sensors are sensitive to the current that is
used during open circuit detection. The current will generate
heat, which is measured and will appear as an offset.
Optional heating
the heater is not necessarily switched on; recommended
operation is to activate the heater when the sun is below the
horizon. Heating power is 12 VDC, 0.5 W at 12 VDC (the
heater is not necessarily active). Some users are operating
the heater at 24 V and 2 W to rapidly remove frost.