Calorimetric pyranometers use plane black thermal sensors which absorb solar radiation. If a thermoresistive transducer (sensor-detector combination) is used, the temperature measured is nearer the true value than for thermoelectric transducers. More importantly, the measurement of electrical power is much more accurate than the measurement of temperature. In commercial platinum (thermoresistive), thin film thermometers, the substrate produces transducer time constants an order of magnitude larger than for the best thermoelectric transducers. Use of an electronic amplifier with the thermoresistive sensor, forming one arm of a Wheatstone bridge and arranged in a negative feedback configuration, can reduce the overall response time considerably. Theoretical formulations of instrument response, taking into account the amplifier input offset voltage, are presented and the response time is estimated.

1.
Beaubien, D. J., Bisberg, A., Beaubien, A. F., and Dichter, B. K., 1994, “A novel total solar pyranometer design,” Eighth Conference on Atmospheric Radiation, p. 188.
2.
Coulson, K. L. and Howell, Y., 1975, Solar and Terrestrial Radiation—Methods and Measurements, Academic Press, San Diego, CA.
3.
Doebelin, E. O., 1982, Measurement Systems: Applications and Design, McGraw–Hill, New York.
4.
Kendall Sr., J. M., Halley, F., and Plamondon, J., 1965, “Cavity type absolute total radiation radiometer,” Twentieth Annual ISA Conference and Exhibition, pp. 1–4.
5.
Lima, L. C., and Lobo, P. C., 1988, “An electrically compensated pyranometer with plane sensors,” ASME Solar Energy Conference, ASME, New York, pp. 392–396.
6.
Lobo, P. C., 1966, “Determination of Velocity Patterns in Engine Cylinders by Means of the Hot Wire Anemometer,” Ph.D. thesis. University of London, London, UK.
7.
Lobo, P. C., 1982, Loss compensated radiometer, ASME Solar Engineering Conference, ASME, New York, pp. 491–495.
8.
Lobo, P. C., Deep, G. S., Freire, R. C. S., Neto, J. S. R., and Lima, A. M. N., 1995, Dynamic response of a feedback thermoresistive electrical substitution pyranometer, ASME Solar Energy Conference, ASME, New York, pp. 751–756.
9.
Nelder, J. A., and Mead, R., 1965, “A simplex method for function minimization,” The Computer Journal, pp. 308–313.
10.
Perry
A. E.
, and
Morrison
G. L.
,
1971
, “
A study of the constant temperature hot-wire anemometer
,”
Journal of Fluid Mechanics
, Vol.
47
, No.
3
, pp.
577
599
.
11.
Sarma, G. R., 1993, “Analysis of a constant voltage anemometer,” IEEE Instrumentation and Measurement Technology Conference, pp. 731–736.
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