SISTEM KONTROL SUHU PADA ALAT PENGERING GABAH BERBASIS MIKROKONTROLER ATMEGA 8 TEMPERATURE CONTROL SYSTEM ON THE PADDY DRYER MACHINE BASED ON ATMEGA 8 MICROCONTROLLER

Abstract

Abstrak

Penelitian ini bertujuan untuk mengetahui diagram blok sistem kontrol suhu pada alat pengering gabah beserta analisis fungsi transfer yang berlaku untuk sistem tersebut dan mengetahui laju transfer panas konveksi dalam tabung pengering gabah. Suhu di dalam tabung pengering gabah dikontrol menggunakan rangkaian sistem kontrol suhu yang tersusun atas dua masukan yang dibandingkan oleh mikrokontroler ATMega 8 yaitu output dari potensiometer (Vref ) dan feedback dari sensor suhu LM 35 DZ (Vsensor). Apabila hasil perbandingan (error) lebih dari 0, maka keluaran mikrokontroler pada port B.5 akan berlogika HIGH yang membuat saklar sistem (optocoupler dan transistor) mengaktifkan relay, sehingga arus AC akan mengalir ke pemanas dan menghasilkan energi berupa panas, begitu juga sebaliknya. Alat ini mampu mengendalikan suhu yang dibutuhkan untuk mengeringkan gabah, yaitu sebesar 50°C dengan waktu pengeringan selama (4-4,5) jam. Diagram blok dan fungsi transfer sistem kontrol suhu pada alat pengering gabah bekerja berdasarkan set point dari potensiometer dan feedback dari sensor suhu LM 35 DZ, yang menjadi acuan mikrokontroler dalam mengendalikan saklar dan aktuator sistem. Koefisien konveksi pada proses pengeringan diperoleh berdasarkan dua kondisi, yaitu sebesar (246,15±100) W/m²°C pada kondisi tabung tanpa gabah dan (-25±80) W/m² °C pada kondisi tabung berisi gabah 3 kg.

Kata kunci: sistem kontrol, suhu, alat pengering gabah, konveksi

Abstract

This research aimed to know the block diagram of temperature control system on the paddy dryer machine and it’s transfer function analysis and to know the convection heat transfer rate inside the dryer tube. The temperature in the dryer tube was controlled by a circuit of temperature control system consisting of two inputs which were compared by ATMega 8 microcontroller. These were the output of the potentiometer (Vref) and feedback from the temperature sensor LM 35 DZ (Vsensor). When the comparison result (error) was higher than 0, then port B.5 of microcontroller would give HIGH logic output to the switching systems (optocoupler and transistor) and the relay would be activated, so that AC current would flow to the heater generating heat. Otherwise, when the error was 0, the relay would be inactivated and there was no heat generated by the heater. This machine was able to control the temperature required for paddy drying process at 50°C with (4-4,5) hour drying time. Block diagrams and transfer function of temperature control system on paddy dryer machine worked based on set point from the potentiometer and feedback from the temperature sensor LM 35 DZ, which became reference for microcontroller to control the switches and actuator system. Convection coefficient on the drying process were obtained in two different conditions, these were (246,15±100) W/m²°C when dryer tube was empty and (-25±80) W/m²°C when dryer tube was filled by 3 kg of paddy.

Keywords: control system, temperature, paddy dryer machine, convection