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Campbell CM 21 Скачать руководство пользователя страница 26

26

The special screen for the
lower CM 21 prevents direct
illumination of the domes by
the sun at sunrise and sunset.
Kipp & Zonen can also supply
this screen for a separate
CM 21 (see chapter 9 for the
part number).

Offset signals generated in the
pyranometer by thermal
effects (see paragraph 1.2.1)
are a factor of 5 more
significant in the
measurement of the reflected
radiation due to the lower
irradiance level. The mast in the
construction of figure 10 intercepts
a fraction

D

/ 2

π

S

of the radiation coming from the ground.

In the most unfavourable situation (sun at zenith) the pyranometer shadow
decreases the signal by a factor

R

2

/

H

2.

3.2.6 Underwater use

The CM 21 pyranometer is in principle watertight. However, the
hemispherical water-glass and glass-air boundaries act as a negative lens.
The parallel beam of direct solar radiation becomes strong divergent after
the passage of the outer dome.
Consequently the intensity at the sensor is lower than outside the
pyranometer. The sensitivity figure is not valid in this case but must be
derived empirically.

Figure 10

Albedo measurement

construction

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Содержание CM 21

Страница 1: ...INSTRUCTION MANUAL CM 21 PYRANOMETER...

Страница 2: ...glect accidents of nature or shipping damage This warranty is in lieu of all other warranties expressed or implied including warranties of merchantability or fitness for a particular purpose CSC is no...

Страница 3: ...TY Kipp Zonen guarantees that the product delivered has been thoroughly tested to ensure that it meets its published specifications The warranty included in the conditions of delivery is valid only if...

Страница 4: ...sole responsibility that the product Type CM 21 Name Pyranometer To which this declaration relates is in conformity with the following standards Imissions EN 50082 1 Group standard Emissions EN 50081...

Страница 5: ...NOMETER ACCORDING TO ISO 9060 LISTING 13 2 2 ACCURACY 16 3 INSTALLATION 19 3 1 DELIVERY 19 3 2 MECHANICAL INSTALLATION 20 3 2 1 Installation for measurement of global radiation 20 3 2 2 Installation f...

Страница 6: ...ric Reference 39 7 FREQUENTLY ASKED QUESTIONS FAQ s 41 8 TROUBLE SHOOTING 43 9 PART NUMBERS SPARE PARTS OPTIONS 45 APPENDIX I CLASSIFICATION ACCORDING TO WMO GUIDE 1996 47 APPENDIX II RADIOMETRIC LEVE...

Страница 7: ...ced to less than 10 W m 2 The special features of the CM 21 are High sensitivity which could result in lower specifications for the data acquisition system Low impedance which reduces sensitivity for...

Страница 8: ...rared radiation thermal radiation 3000 nm from the environment e g the inner dome The radiant energy is absorbed by a black painted disk The heat generated flows through a thermal resistance to the he...

Страница 9: ...te plastic screen reduces the body temperature variations due to solar radiation and cold rain showers Zero offset type A This zero offset is present when there is a temperature difference between the...

Страница 10: ...zero offset type A is the result Zero offset type A can be checked by placing a light and IR reflecting cap over the pyranometer The response to solar radiation will decay with a time constant 1 e of...

Страница 11: ...roperties of the sensor For a given heat flow the sensitivity of the pyranometer is a function of the thermal conductivity of the sensor and of the thermo electric power of the thermocouple material B...

Страница 12: ...12...

Страница 13: ...s 95 response 1 6 s 63 response Non linearity 0 2 1000 W m 2 Spectral selectivity 2 Temperature dependence of sensitivity 1 20 C to 50 C Directional error 10 W m 2 beam 1000 W m 2 Tilt error 0 2 beam...

Страница 14: ...Quartz domes Schott K5 optical glass 2 mm thick 30 mm and 50 mm outer diameter Desiccant Silica gel Spirit level Sensitivity 0 1 degree bubble half out of the ring Integral with base of instrument Det...

Страница 15: ...15 Figure 2 CM 21 Pyranometer outline dimensions in mm 92 5 mm 150 mm 6 mm 65 mm L 10 m 2 TECHNICAL DATA...

Страница 16: ...er if the integration period is long Kipp Zonen expects max errors of 2 for hourly totals and 2 for daily totals These remaining errors can be reduced further if the actual sensitivity of the pyranome...

Страница 17: ...The curve of relative sensitivity variation with instrument temperature of a CM 21 pyranometer is in the shaded region The directional error is the summation of the azimuth and zenith error and is co...

Страница 18: ...ected E g at a sun s elevation of 30 air mass 2 only 1 of the solar radiation has wavelengths below 335 nm and only 1 has wavelengths above 2200 nm Figure 5 CM 21 Black absorbers relative absorption F...

Страница 19: ...te the repair or replacement of the instrument The CM 21 pyranometer delivery will include the following items 1 CM 21 pyranometer 2 White sun screen 3 2 x Mounting bolts nuts washers M5 x 80 4 2 x ny...

Страница 20: ...earliest sunrise and latest sunset should have an elevation not exceeding 5 The apparent sun diameter is 0 5 This is important for an accurate measurement of the direct solar radiation The diffuse sol...

Страница 21: ...are provided The pyranometer should first be secured lightly with the bolts to a mounting stand or platform Shown in figure 7 Note After reinstallation and recalibration the nylon insulators must be...

Страница 22: ...22 Figure 7 Mounting the pyranometer Screw M5x80 Nylon insulator Washer M5 Nut M5...

Страница 23: ...endix II Finally the pyranometer should be secured tight with the two stainless steel bolts Ensure that the pyranometer maintains the correct levelled position 3 2 2 Installation for measurement of so...

Страница 24: ...screen prevents direct illumination of the domes by the sun at sunrise and sunset Offset signals generated in the pyranometer by thermal effects see paragraph 1 2 1 are a factor of 5 more significant...

Страница 25: ...cepts the direct solar radiation some days without readjustment but also a proportion of the diffuse sky radiation Therefore corrections for this to the recorded data are necessary Kipp Zonen supplies...

Страница 26: ...10 intercepts a fraction D 2 S of the radiation coming from the ground In the most unfavourable situation sun at zenith the pyranometer shadow decreases the signal by a factor R 2 H 2 3 2 6 Underwate...

Страница 27: ...case is advised Looking at the circuit diagram of figure 11 it is clear that the impedance of the readout equipment is loading the thermistor circuit and the thermopiles It can increase the temperatur...

Страница 28: ...t the result can be read directly in W m 2 Figure 11 Circuit diagram of the CM 21 pyranometer and connection to readout equipment When an optional temperature sensor is built in See specifications in...

Страница 29: ...esolution is not necessary during outdoors solar radiation measurements because pyranometers exhibit offsets up to or 2 W m 2 due to lack of thermal equilibrium A surge arrester is installed to conduc...

Страница 30: ...30...

Страница 31: ...ar S U E formula 1 E Solar Global radiation W m 2 Uemf Output of pyranometer V Sensitivity Sensitivity of pyranometer V W m 2 To be certain that the quality of the data is of a high standard care must...

Страница 32: ...32...

Страница 33: ...e instrument is level and that there is no condensation inside the dome If there is condensation the silica gel must be replaced even when the colour is still blue Apparently the location requires ver...

Страница 34: ...as to be checked at yearly intervals So due to pressure differences inside and outside the instrument there will always be some exchange of humid air In some networks the exposed dome of the pyranomet...

Страница 35: ...ver this has no consequences for the transfer of calibration because standard and unknown pyranometer have the same black coating and glass domes The supplied sensitivity figure is valid for the follo...

Страница 36: ...the instrument with a disk There is however no thermal equilibrium with this method and some pyranometer models show zero offset drift There is another procedure during which the unknown pyranometer r...

Страница 37: ...is centred on the rotating axis of this table Actually there is no normal incidence of the radiation But the angle of incidence is the same for both pyranometers 3 so this cannot give rise to errors...

Страница 38: ...andard pyranometer at position 2 B Output of standard pyranometer at position 1 Sa Sensitivity of the pyranometer at 20 C Output mean value at 100 response minus zero offset signal 6 3 4 Zero offset T...

Страница 39: ...ipp Zonen Each standard pyranometer is characterised Linearity temperature dependence curve and directional response are well known The working standard pyranometers are calibrated each year at the Wo...

Страница 40: ...40...

Страница 41: ...air by wind and from the inner dome through infrared radiation The inner dome is cooling down too and will attract heat from the body by conduction and from the sensor by the net infrared radiation T...

Страница 42: ...vents of some minutes duration 3 What is the primary entry point for humidity The desiccant cartridge and cable glands have equal chances to transport some moisture but also the silicon glue of the do...

Страница 43: ...during some part of the day Check the window it should be clear If water is deposited on the inside please change the desiccant If too much water is deposited the instrument should be dried internall...

Страница 44: ...44...

Страница 45: ...2 426 Screen plastic 0305 166 Levelling screw 2 required per pyranometer 0012 117 Fixed foot 0012 116 Level with holder 2993 100 0012 108 Complete drying cartridge consisting of Clamp Spring 0305 165...

Страница 46: ...connectors 0305 631 20 meters cable extension and connectors 0305 632 25 meters cable extension and connectors 0305 633 30 meters cable extension and connectors 0305 634 50 meters cable extension and...

Страница 47: ...ponsivity is valid for all directions when measuring from any direction a beam radiation whose normal incidence irradiance is 1000 W m2 10 W m 2 10 W m 2 20 W m 2 30 W m 2 Temperature response percent...

Страница 48: ...48...

Страница 49: ...adiation falls at an elevation of approximately 15 to the horizontal the lamp should be fed by a constant voltage supply The output from the radiation instrument is measured at various azimuths and th...

Страница 50: ...50...

Страница 51: ...igeria 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 Regi...

Страница 52: ...52...

Страница 53: ...iddle and at the end For each beam incident angle the dark signal is interpolated During the CM 21 measurement cycle a check is done on the azimuth error at 40 and 70 by measuring voltages for azimuth...

Страница 54: ...09 0 10 80 0 62 Absolute cosine error for 1000 W m 2 beam radiation Angle North West South East 40 2 04 W m 2 2 32 W m 2 2 89 W m 2 1 40 W m 2 60 3 06 W m 2 70 2 11 W m 2 2 25 W m 2 3 73 W m 2 0 35 W...

Страница 55: ...2480 49940 47540 45270 43110 41070 39140 37310 35570 33930 32370 30890 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 29490 28150 26890 25690 24550 23460 22430 21450 2...

Страница 56: ...56...

Страница 57: ...99 22 99 61 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 100 00 100 39 100 78 101 17 101 56 101 95 102 34 102 73 103 12 103 51 103 90 104 29 104 68 105 07 105 46 10...

Страница 58: ...58...

Страница 59: ...two years This can be done at the Kipp Zonen factory Here recalibration to the highest standards can be performed at low cost Recalibration can usually be performed within four weeks If required urgen...

Страница 60: ...60...

Страница 61: ...Qty Requested delivery time I intend to send the instruments to Kipp Zonen on I would like to receive the instrument s back on Conformation by Kipp Zonen Yes the dates are acceptable to us No unfortun...

Страница 62: ...62...

Страница 63: ...Qty Requested delivery time I intend to send the instruments to Kipp Zonen on I would like to receive the instrument s back on Conformation by Kipp Zonen Yes the dates are acceptable to us No unfortun...

Страница 64: ...64...

Страница 65: ...Qty Requested delivery time I intend to send the instruments to Kipp Zonen on I would like to receive the instrument s back on Conformation by Kipp Zonen Yes the dates are acceptable to us No unfortun...

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