装在强制通风防辐射罩中的微丝热电偶
概览
ASPTC-L 包括一个置于强制通风防辐射罩内的E型微丝热电偶，可以提供高精确度的温度测量。单独一个ASPTC 可以测量空气温度，也可使用2个ASPTC测量温度差。通常，在波文比系统中，用ASPTC代替TCBR热电偶或作为额外测量使用。
优势与特点
- 使用微丝热电偶进行精确的空气温度测量
- 包含强制通风防辐射罩
- 大功率风扇减少了太阳辐射加热效应
图像
技术说明
ASPTC 的防辐射罩为细长管，采用白色抗UV聚乙烯材料，低导热系数，具有保温性。风扇抽取空气使其通过测量连接点，可减少射向热电偶的太阳光。防辐射罩也可保护热电偶，延长其使用寿命。
ASPTC 细线热电偶的连接点使用了镍铬合金和康铜丝。不同温度的热电偶测量端与热电偶参比端产生的电位差即为电压电势。因此，可通过测量连接点的两根导线所产生的电位差来确定温度。热电偶电压电势的大小与温度差相关。
热电偶测量要求参考温度，许多我们的数据采集器接线面板内置温度传感器，可以测量参考温度。
产品规格
| Shield Material | UV-stabilized polyethylene |
| Large Diameter | 5.8 cm (2.3 in.) |
| Small Diameter | 4.6 cm (1.8 in.) |
| Power Cable Diameter | 0.5 cm (0.2 in.) |
| Signal Cable Diameter | 0.3 cm (0.1 in.) |
| Length | 53.3 cm (21 in.) |
| Height | 14.7 cm (5.8 in.) |
| Weight | 0.86 kg (1.9 lb) |
Fan |
|
| Air Velocity at Thermocouple | 5.5 m/s (@ 12 Vdc) |
| Life Expectancy | 65,000 h (@ 30°C) |
| Current Drain | 260 mA (@ 12 Vdc) |
| Operating Voltage | 9 to 13 Vdc |
| Operating Temperature Range | -10° to +70°C |
| Polarity Protection | Reverse polarity protected |
Thermocouple |
|
| Type | Chromel-Constantan |
| Typical Output | 60 μV/°C |
| Accuracy | Refer to the Thermocouple Measurement section in the data logger manual. |
| Diameter | 0.0762 mm (0.003 in.) |
兼容性
Please note: The following shows notable compatibility information. It is not a comprehensive list of all compatible products.
数据采集器
| Product | Compatible | Note |
|---|---|---|
| CR1000X | ||
| CR3000 (retired) | ||
| CR6 | The CR6 is compatible when used with the CDM-A108 or CDM-A116. | |
| CR800 (retired) | ||
| CR850 (retired) |
Additional Compatibility Information
Mounting
The ASPTC can be mounted to a tripod or tower via the UT018-5 crossarm or a user-supplied crossarm that has a square cross-section of 3.8 cm by 3.8 cm (1.5 in. by 1.5 in.). For circular cross-section crossarms, a mounting bracket kit designed for circular crossarms comes with the ASPTC and can replace the square bracket.
Power Considerations
The ASPTC is typically powered with a user-supplied deep-cycle battery that is recharged with an SP20R, SP50, or SP90 solar panel; for high current drain systems, two SP90 solar panels may be used to provide 180 W of power. The data logger’s rechargeable battery can only be used if it is connected to ac power. For help analyzing your system’s power requirements, refer to our Power Supply brochure or application note.
相关技术文档
常见问题解答
ASPTC-L: 5
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Design the station power supply to meet the power demand of the ASPTC-L fan(s). The data acquisition system should have provisions to turn off the ASPTC-L fan(s) if the battery voltage falls below some threshold. Do not turn the fan(s) off at night during normal operation, however, because under clear sky conditions, the ASPTC-L shield emits long-wave radiation and cools to a temperature lower than ambient air temperature. Running the fan(s) ensures that the thermocouple is measuring ambient air temperature, rather than a reduced temperature caused by long-wave radiation cooling.
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No. Replacing the thermocouple requires completely disassembling the fan and shield. It is best to replace the ASPTC-L with a spare and send the broken one back to the factory for repair and cleaning. To request a return material authorization (RMA) number, follow the steps listed on our Repair and Calibration page. Request pn 16537, ASPTC-L Cleaning and Repair Fee.
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The fan used to aspirate the thermocouple is rated to -10°C.
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No. The ASPTC-L was not designed to measure high-frequency temperature fluctuations. Rather, it was designed to measure the mean air temperature or mean air temperature gradients. To find sensible heat flux using the eddy-covariance technique, consider using a sonic anemometer and an FW05 Fine Wire Thermocouple.
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No. If the fan is off during the day, the shield will suffer from radiation loading, and the thermocouple will measure a higher ambient air temperature. If the fan is off during the night, under clear sky conditions, the ASPTC-L shield will emit long-wave radiation and cool to a temperature lower than ambient air temperature. Consequently, the thermocouple will measure a lower ambient air temperature. Running the fan and aspirating the thermocouple ensures that it is measuring ambient air temperature.
If the site temperature is expected to fall below -10°C, consider using a naturally aspirated fine-wire thermocouple, such as the FW3, FW1, or FW05, in combination with the FWTM Fine-Wire-Thermocouple Mount and the FWC-L Connector Cable for Fine Wire Thermocouples.