下雨感測器之性能評估

Abstract

受氣候變遷的影響，強降雨、乾旱與氣溫升高等氣候變異已經干擾糧食生產，威脅糧食安全，在提升我國糧食自給率政策指導之下，設施生產面積逐年增加。台灣的氣候型態春季梅雨、夏季高溫高濕還有颱風、冬季寒流，設施栽培講求夏天降溫與冬天保溫並重，夏季炎熱多雨問題，需要適度的自然對流通風、遮陰或噴細霧，因此具有遮雨透氣功能的活動式天窗逐漸受到重視，設施屋頂裝設捲收塑膠布或氣窗(天窗)的溫室日漸增多，下雨時人不在溫室該怎麼辦？若沒有設備輔助，只能趕赴現場關窗了。而有了應用工業技術開發的下雨感測器，配合機電控制技術就可以在下雨時自動關窗。試驗之下雨感測器概略分成三種：重量式、電阻式與光學式，2015 年1 月13 日彰化縣大村鄉實測結果顯示，光學式反應最靈敏，電阻式次之且會有誤動作，重量式需在累積足夠雨水之下才會動作；當雨過天晴時，下雨訊號停止也是光學式反應最靈敏，重量式與電阻式都需經過一段時間讓雨水蒸發後，訊號才會改變。價格方面光學式較貴，進口的重量式次之，電阻式最便宜。 Torrential rain, drought and higher temperature are threaten food security due to climate change. Protected culture acreage is increasing in the enhance food self-sufficiency rate policy in Taiwan. Taiwan’s climate patterns are rainy spring, high temperature and high humidity as well as typhoons in summer, and cold wave in winter. Local greenhouse emphasizes both reduce temperature in summer and insulation in winter, and also require moderate natural ventilation, shading or misting in the rainy and hot summer. So the activity roof-window that can protect crop from rain and vent in the sunny day has be taken seriously. Greenhouses mounted with activity roof-window are increasing. The activity roof-window has two kinds, retractable and rolling plastic cover, all need to be closed the roof-window when rainy. Rain sensor with electromechanical control technology can automatically close the roof-window when it rains. There are three types of rain sensors: weight, resistive and optical. The experiment was conducted in Tacun Township, Changhua County on 13th January, 2015. The best performance of rain sensor is optical type and weight type has the least sensitivity because it need take time to soak rain drop. The optical type is expensive, followed by imported weight type, and then resistive type.