TBS-2C Automatic Tracking Direct Radiometer
Principle and structural characteristics
The table structure is shown in Figure 1, mainly composed of a light tube and an automatic tracking device. The inside of the light tube is composed of seven light barriers, inner tube, thermopile and desiccant tube. Seven diaphragms are used to reduce internal reflections, form the opening angle of the instrument and limit the turbulence of the air inside the instrument. Outside the diaphragm is an inner cylinder, which seals the dry air inside and outside the diaphragm to reduce the influence of ambient temperature on the thermopile. There is a JGS3 quartz glass sheet on the outer cylinder mouth, which can transmit radiation with a wavelength of 0.27-3.2μm, which is convenient for direct solar radiation measurement. A desiccant is installed in the cylinder to prevent the formation of water vapor condensation.
The sensing part of the direct pyranometer is the core part of the light tube, which is composed of a fast-response wire-wound electroplated thermopile. The sensing part is coated with matt black paint on one side facing the sun, and the hot junction of the thermopile is underneath. When sunlight hits the hot junction, the temperature rises. It forms a temperature difference with the cold junction on the other side, thereby generating electromotive force. It is proportional to the direct solar radiation intensity.
The automatic tracking device is composed of a bottom plate, a latitude dial, a stepping motor, a conductive ring, a turbine box (used for sun inclination adjustment) and other components. The stepping motor is the power source, it can only be controlled and operated by the "direct meter controller" produced by our company (the automatic tracking device cannot be screwed by hand). The tracking device has high accuracy, and the rotation angle error within a week is within 0.25°, that is, less than 1 minute. As long as it is installed correctly, accurate automatic tracking can be achieved.
