CM 4 High Temperature Pyranometer Instruction Manual
IMPORTANT USER INFORMATION Reading this entire manual is recommended for full understanding of the use of this product. The exclamation mark within an equilateral triangle is intended to alert the user to the presence of important operating and maintenance instructions in the literature accompanying the instrument. Should you have any comments on this manual we will be pleased to receive them at: Kipp & Zonen B.V. Delftechpark 36 2628 XH Delft Holland P.O.
COPYRIGHT© 2010 KIPP & ZONEN All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, without permission in written form from the company.
CALIBRATION CERTIFICATE The calibration certificate supplied with the instrument is valid from the date of first use. Even though the calibration certificate is dated relative to manufacture the instrument does not undergo any sensitivity changes when kept in the original packing. From the moment the instrument is taken from it’s packaging and exposed to irradiance the sensitivity will deviate with time. See also the 'nonstability' performance (max.
DECLARATION OF CONFORMITY According to EC guideline 89/336/EEC We Kipp & Zonen B.V. Delftechpark 36 2628 XH Delft The Netherlands Declare under our sole responsibility that the product Type: Name: CM 4 High Temperature Pyranometer To which this declaration relates is in conformity with the following standards Imissions EN 50082-1 Group standard Emissions EN 50081-1 EN 55022 Group standard Following the provisions of the directive B.A.H. Dieterink President KIPP & ZONEN B.V.
5
6
TABLE OF CONTENTS IMPORTANT USER INFORMATION ..............................................1 CALIBRATION CERTIFICATE .......................................................2 DECLARATION OF CONFORMITY ...............................................4 1 GENERAL INFORMATION........................................................9 1.1 1.2 1.2.1 1.2.2 1.2.3 1.2.4 INTRODUCTION ...................................................................9 PHYSICAL PRINCIPLES OF THE PYRANOMETER ....................
6.3.5 Traceability to World Radiometric Reference ..............35 7 FREQUENTLY ASKED QUESTIONS (FAQ’S).......................37 8 TROUBLE SHOOTING ............................................................39 9 PART NUMBERS / SPARE PARTS / OPTIONS.....................41 APPENDIX I PYRANOMETER CLASSIFICATION ACCORDING TO WMO GUIDE 1996 ............43 APPENDIX II PT-100 SPECIFICATIONS .............................45 APPENDIX III LIST OF WORLD AND REGIONAL RADIATION CENTRES............................
1. GENERAL INFORMATION 1 GENERAL INFORMATION 1.1 INTRODUCTION The CM 4 High Temperature Pyranometer is an instrument for measuring solar or artificial light irradiance. The instrument is specially designed for usage under extreme irradiance and temperature conditions. With an operating temperature range of -40°C to +150°C and measurement up to 4000 W/m² it is a unique product.
The CM 4 Pyranometer complies with specifications according to the ISO 9060 standard, as defined in the ‘Guide to meteorological Instruments and Methods of Observation’, sixth edition, 1996, of the World Meteorological Organisation (WMO*) – Geneva – Switzerland. * The WMO classification is adapted from the international standard ISO 9060 (1990). 1.2 PHYSICAL PRINCIPLES OF THE PYRANOMETER The pyranometer basically consists of a thermopile detector, aluminium housing, a glass dome and a special cable.
1. GENERAL INFORMATION The thermopile surface is coated with black absorbent paint. Absorbed radiation is converted into heat which flows through the thermal resistance of the thermopile to the heat-sink. The temperature difference (ΔT) across the thermal resistance of the detector is converted into a voltage. Most electrical and physical specifications are determined by the thermopile. The thermopile and the dome determine the spectral specifications.
Temperature dependency of the sensitivity Temperature dependency [%] 3.000 2.000 1.000 0.000 -1.000 - 2.000 - 3.000 -40 - 20 0 20 40 60 80 100 120 140 160 Instrument temperature (°C) Figure 1.2: Typical temperature dependency curve of the CM 4. The CM 4 High Temperature Pyranometer is supplied with its own individual graph of temperature dependence of sensitivity. Monitoring the temperature during operation will allow easy data correction afterwards for improved measurement accuracy.
1. GENERAL INFORMATION 1.2.2 Spectral properties of the glass dome The spectral properties of a pyranometer are determined by the properties of the black absorbent paint and the glass dome. The spectral response is given in figure 1.3. Figure 1.3: The spectral transmission of the glass dome pyranometer combined with the spectrum of the sun under a clear sky.
1.2.3 Directional / Cosine response The measurement of the radiation falling on a plane surface (also called irradiance or radiative flux) requires two assumptions: that the surface is spectrally black (that it absorbs all radiation of all wavelengths) and that it has a 180° field of view. Another way of expressing these directional properties is to say that the sensor has to comply with an ideal cosine response.
1. GENERAL INFORMATION 10 8 6 min. cosine error % 4 typical cosine error % [%] 2 max. cosine error % 0 0 10 20 30 40 50 60 70 80 -2 -4 -6 Figure 1.4: degrees The mean cosine response of the pyranometer. With the angle of incidence on the horizontal axis and the percentage deviation from ideal cosine behaviour on the vertical axis. 1.2.4 Non-linearity Non-linearity is the error of the sensitivity variation as a function of the variation in irradiance.
Relative error [-] 1.01 1.00 0.99 0.98 0.97 0.96 0 500 1000 1500 2000 2500 Irradiance [W/m²] Figure 1.5: CM 4 non-linearity, sensitivity variation as a function of the irradiance, with 500 W/m² as reference level during calibration.
SPECIFICATIONS 2 LIST OF SPECIFICATIONS Spectral range: 300 to 2800 nm, 50% points Sensitivity: 7 µV/Wm-2 (nominal) Impedance: 500 to 2000 Ω Response time: 18 s <8s Non-linearity: Max. 3 % (0 - 2500 W/m2) Directional error (at 80° with a 1000 W/m² beam): ± 20 W/m² Temperature dependence of sensitivity: Tilt error: Zero-offset due to temperature changes: (95% response) (63% response) 3 % (-20 °C to +0 °C) 2 % (0 °C to +100 °C) 3 % (+100 °C to +150 °C) Max.
Temperature sensor: Pt-100 Construction: Receiver paint: Carbon Black Dome: Glass Desiccant: Silica gel Materials: Anodised aluminium case Stainless steel screws etc Viton O-rings Drying cartridge aluminium and glass lid Cable material: 6-wire shielded cable Pt-100 specifications: Type Heraeus M-GX 1013, DIN IEC 751. Class A, See Appendix II Shock / vibration: IEC 721-3-2-2m2 CE according to EC guideline 89/336/EEC 73/23/EEC Environmental: Intended for continuous outdoor or indoor use.
SPECIFICATIONS Figure 2.1: CM 4 Dimensions.
20
3. INSTALLATION 3 INSTALLATION Reading the installation instruction before installation is recommended for full understanding of the use of this product. 3.1 DELIVERY Check the contents of the shipment for completeness (see below) and note whether any damage has occurred during transport. If there is damage, a claim should be filed with the carrier immediately.
3.2.1 Outdoor installation When installed permanently, the pyranometer can be attached to its mounting platform by means of the holes that are drilled through the body, see figure 2.1. Preferred orientation is with the cable pointing to the nearest pole. When installed on a mast, preferred orientation is such that no shadow is cast on the pyranometer during any time of the day. In the Northern hemisphere this implies that the pyranometer should be south of the mast.
3. INSTALLATION 3.3 ELECTRICAL CONNECTION The CM 4 is provided with a special 10 m cable with six leads and a shield covered with a black sleeve. The colour code is: red blue Shield = = = plus minus case Pt-100 temperature sensor (4 – wire connection) White: Black: Green: Yellow: Pt 100 (combined with black) Pt 100 (combined with white Pt 100 (combined with yellow) Pt 100 (combined with green) The shield is directly connected to the case.
Figure 3.1: Circuit diagram of the CM 4 Pyranometer and connection to readout equipment. It is evident that application of attenuator circuits to the CM 4 output in order to modify the calibration factor is not recommended because the temperature response will also be affected. However, recorders with a variable voltage range can be set so that the result can be read out directly in W/m2.
3. INSTALLATION For amplification of the pyranometer signal Kipp & Zonen recommends the 4-20 mA Signal Amplifier, available from Kipp & Zonen. This amplifier converts the micro-Volt output from the pyranometer into a standard 4–20 mA signal. Zero and Span adjustment of the pyranometer signal are provided.
26
4. OPERATION 4 OPERATION After completing the installation the pyranometer will be ready for operation. The irradiance value (E) can be simply computed by dividing the output signal (Uemf) of the pyranometer by its sensitivity (Sensitivity) as shown in formula 1, or by multiplication of the voltage value with the reciprocal of the sensitivity, often called the calibration factor. The CM 4 pyranometer sensitivity is given in the supplied calibration certificate.
28
5. MAINTENANCE 5 MAINTENANCE Once installed the pyranometer needs little maintenance. The pyranometer dome must be kept clean and inspected regularly. Ensure that the silica gel is still coloured orange. When the orange silica gel in the drying cartridge is turned completely transparent (normally after several months), it must be replaced by active silicagel as supplied in the small refill packs. The content of one pack is sufficient for one complete refill.
30
6. CALIBRATION 6 CALIBRATION 6.1 INITIAL CALIBRATION The ideal pyranometer should always have a constant ratio of voltage output to irradiance level (outside the instrument in the plane of the sensing element). This ratio is called sensitivity (Sensitivity) or responsivity. The calibration (sensitivity) factor of a particular pyranometer is unique. It is determined in the manufacturer's laboratory by comparison against a reference pyranometer.
Accurate calibrations can also be done outdoors under clear conditions by comparison to a reference pyrheliometer. Many National Weather Services have calibration facilities. Their standard pyrheliometer is compared with the World Radiometric Reference (maintained at Davos, Switzerland) embodied by several absolute pyrheliometers (black body cavity type). The comparisons are performed indoors or outdoors at one of the regional Radiation Centres, see Appendix III.
6. CALIBRATION 6.3 CALIBRATION PROCEDURE AT KIPP & ZONEN 6.3.1 The facility The calibration facility at Kipp & Zonen consists of a good quality film sun (Osram) fed by an AC voltage stabiliser. This is used as an artificial sun. It embodies a 150 W Metal Halide lamp with compact filament. To minimise stray light from the walls and the operator, the light is limited to a small cone around the two pyranometers.
the lamp optics etc. Therefore the pyranometers are interchanged and the whole procedure is repeated. We get another pair of values: A' and B'. 6.3.3 Calculation The sensitivity of the unknown pyranometer is calculated using formula 2: S Sb A A’ B B’ Sa a = A + A' ⋅ B + B ' sb (Formula 2) = Sensitivity of the reference pyranometer at 20 °C.
6. CALIBRATION 6.3.5 Traceability to World Radiometric Reference Working reference pyranometers are maintained at Kipp & Zonen. Each reference pyranometer is characterised. Linearity, temperature dependence curve and directional response are well known. The working reference pyranometers are calibrated each year at the World Radiation Center in Davos, Switzerland, according to the component method.
36
7 7 FREQUENTLY ASKED QUESTIONS FREQUENTLY ASKED QUESTIONS (FAQ’s) The most frequently asked questions are listed below. 1. Negative output during measurements? This error is related to the zero offset type A. Normally this zero offset is present when the dome has a different temperature from the cold junctions of the sensor. In practice this is always the case when there is very large and cold object close to the pyranometer.
38
8 8 TROUBLE SHOOTING TROUBLE SHOOTING The following contains a procedure for checking the instrument in case it appears that it does not function as one could expect. Trouble shooting: Output signal fails or shows improbable results: Check the wires, whether they are properly connected to the readout equipment. Check the dome and the drying cartridge, they should be clear. If water is deposited on the inside, please change the desiccant.
40
9 9 PART NUMBERS / SPARE PARTS / OPTIONS PART NUMBERS / SPARE PARTS / OPTIONS Description Part no. Drying Cartridge kit (incl.
42
APPENDIX I PYRANOMETER CLASSIFICATION ACCORDING TO WMO GUIDE 1996 High quality Good quality Moderate quality Secondary standard First class Second class < 15 s < 30 s < 60 s ± 7 W/m2 ± 15 W/m2 ± 30 W/m2 ± 2 W/m2 ± 4 W/m2 ± 8 W/m2 ± 1 W/m2 ± 5 W/m2 ± 10 W/m2 ± 0.8 ± 1.5 ± 3.
Achievable uncertainty, 95 percent confidence level Hourly totals Daily totals 44 3% 2% 8% 5% 20% 10%
APPENDIX II PT-100 SPECIFICATIONS Temp. [°C] Resistance [Ω] Temp. [°C] Resistance [Ω] Temp.
46 Temp. [°C] Resistance [Ω] Temp. [°C] Resistance [Ω] Temp.
APPENDIX III LIST OF WORLD AND REGIONAL RADIATION CENTRES World Radiation Centres Davos (Switzerland) St. Petersburg (Russia) Regional Radiation Centres Region I Africa: Cairo (Egypt) Khartoum (Sudan) Kinshasa (Zaire) Lagos (Nigeria) Tamanrasset (Algeria) Tunis (Tunisia) Region II Asia: Poona (India) Tokyo (Japan) Region III South America: Buenos Aires (Argentina) Region IV North and Central America: Toronto (Canada) Washington (U.S.A.
48
APPENDIX IV RECALIBRATION SERVICE Pyranometers, UV-meters, Pyrgeometers & Sunshine duration sensors Kipp & Zonen solar radiation measurement instruments comply with the most demanding international standards. In order to maintain the specified performance of these instruments, Kipp & Zonen recommends calibration of their instruments at least every two years. This can be done at the Kipp & Zonen factory. Here, recalibration to the highest standards can be performed at low cost.
50
RECALIBRATION FORM Name Company/Institute Address Postcode + City Country Phone Fax E-mail : : : : : : : : I would like to receive a price estimate for recalibration I would like to submit my instruments for recalibration Type/Model: Qty: Requested delivery time I intend to send the instrument(s) to Kipp & Zonen on: . . . . . ./. . . . . ./. . . . . . I would like to receive the instrument(s) back on: . . . . . ./. . . . . ./. . . . . .
Our customer support remains at your disposal for any maintenance or repair, calibration, supplies and spares. Für Servicearbeiten und Kalibrierung, Verbrauchsmaterial und Ersatzteile steht Ihnen unsere Customer Support Abteilung zur Verfügung. Notre service 'Support Clientèle' reste à votre entière disposition pour tout problème de maintenance, réparation ou d'étalonnage ainsi que pour les accessoires et pièces de rechange.
