Programmable switching of loads is a necessary option for the process industries to operate sequential processes that eventually lead to end product. In this era of industrial automation, most of the industries are automated, and such automation requires that the loads to be operated should be done in a preprogrammed manner. And also during the load shedding process, the utilities department performs the loads to be turned on or off for particular periods mainly during power recession seasons.
This article is intended to give practical information about the programmable switching of the loads that are varied by the user requirements using embedded systems. Each project explains how the programmable switching is achieved using Android, Real-time clock and other controlling devices.
1. Android-based Remotely Programmable Sequential Load Operation
The objective of this project is to facilitate the loads, that are to be operated either manually or automatically, by using remote Android mobile, and also is to help adjust the duration time to turn ‘On’ or ‘Off’ the loads. Once they are set to automatic mode, loads will remain in repetitive mode of switching until they get the next command from the phone.
Three modes of operation of this circuit are auto, manual and set mode. In a set mode, a user is allowed to change the settings, i.e., the time to turn on the loads. This entire system works on Bluetooth that is attached to the circuit.
An Android-based phone with a corresponding application to control the system initiates the operation of the circuit.
Whenever the corresponding button to auto-mode is pressed in the Android phone, the microcontroller senses that signal and correspondingly switches the loads set by the user.
When a manual button is pressed the switches corresponding to each lamp in Android application enable the lamps to be turned on with the help of the microcontroller. The status of all the modes gets displayed on LCD display. A relay driver switches all the lamp loads based on the signals from the microcontroller.
2. Programmable Load Shedding Time Management for Utility Department
This project is quite similar to the above project, except that it involves a matrix keypad. It uses a RTC (Real Time Clock) to match the operating time exactly with the real clock. It also helps to change the time sequence of each load based on the user requirement.
The Matrix keypad allows users to enter time values for each load as on and off periods. Microcontroller stores these values and executes them by comparing with the timer clock provided by the RTC. As the time matches, the microcontroller sends command signals to a relay driver that drives different loads. (here lamp loads)
A seven segment display is used to display the time when a user enters and executes timer values. This display also displays the current load number that is being operated at the moment. This is a low-powered and low-cost embedded project suitable for programmable switching of loads in a repetitive mode.
3. Programmable AC Power using Thyristors
This project is an advanced one compared to the above two projects as the above mentioned projects have only two states: either ‘Off’ or ‘On’ of the loads is possible in the above two projects.
This project is implemented to supply the required power to the load that is programmable based on the user requirement. At times, Some of the loads must be operated at a certain lower levels or lesser percentage of the total load– for instance, a fan must rotate based on the temperature that prevails.
Therefore, according to the user requirement, the load can be operated at different levels of its capacity by adjusting the power supplied to it. Hence, AC power is controlled by using a triac that belongs to a thyristor family.
The percentage of the load required is entered with the help of a matrix keypad, and then the data is sent to the microcontroller. The microcontroller is programmed in such a way that it adjust the firing pulses applied to the triac. Opto isolator is used in this circuit to isolate the voltage levels of the microcontroller and triac.
In this system, the traic acts as a switch and thus allows the required percentage of the power to flow through the circuit based on the trigerring pulses applied by the micrcontroller circuit. The amount of the load being operated is displayed on the LCD display. This is how the programmable power is supplied to the load.
These are some of the main projects that schedule power applied to the loads programmatically. These are all embedded systems based projects that use microcontroller as a main controller and are as a result low cost and self implemented projects.
This is all about the projects on schedule power or programmable load switching. Furthermore, for any doubts, queries and help regarding these projects and others you can comment in the comment section given below.