AUTOMATIC LOAD SHARING OF TRANSFORMERS
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1.1 EMBEDDED SYSTEMS:
Embedded systems are designed to do some specific task, rather than be a general-purpose computer for multiple tasks. Some also have real time performance constraints that must be met, for reason such as safety and usability; others may have low or no performance requirements, allowing the system hardware to be simplified to reduce costs.
An embedded system is not always a separate block - very often it is physically built-in to the device it is controlling. The software written for embedded systems is often called firmware, and is stored in read-only memory or flash convector chips rather than a disk drive. It often runs with limited computer hardware resources: small or no keyboard, screen, and little memory.
Wireless communication has become an important feature for commercial products and a popular research topic within the last ten years. There are now more mobile phone subscriptions than wired-line subscriptions. Lately, one area of commercial interest has been low-cost, low-power, and short-distance wireless communication used for \personal wireless networks." Technology advancements are providing smaller and more cost effective devices for integrating computational processing, wireless communication, and a host of other functionalities. These embedded communications devices will be integrated into applications ranging from homeland security to industry automation and monitoring. They will also enable custom tailored engineering solutions, creating a revolutionary way of disseminating and processing information. With new technologies and devices come new business activities, and the need for employees in these technological areas. Engineers who have knowledge of embedded systems and wireless communications will be in high demand. Unfortunately, there are few adorable environments available for development and classroom use, so students often do not learn about these technologies during hands-on lab exercises. The communication mediums were twisted pair, optical fiber, infrared, and generally wireless radio.
ABSTRACT TO THE PROJECT:
In this project “AUTOMATIC LOAD SHARING OF TRANSFORMERS” we are using two transformers, one is main transformer (TF1) and the next is backup transformer (TF2). Here the load is directly connected to the secondary of the main transformer as well as backup transformer; here two transformers are connected through the relay.
The transfers switch senses when utility power is interrupted, and starts up the transformer TF2 which acts as a backup transformer. If the utility power remains absent, the transfer switch disconnects the load from the utility and connects it to the Transformer TF2, restoring electricity to the load. The transfer switch continues to monitor utility power, and when it is restored, switches the load from the Transformer TF2 back to the Main transformer TF1. Once the Transformer TF2 is disconnected, it goes through a cool-down routine and is automatically shut down.
The objective of the present project is to satisfy the above needs with an extent. The present system is designed around two transformers. One transformer (TF1) is used as the main supply and the other transformer (TF2) is used in the place of the generator (for demo purpose). These two transformers are connected with the relay which is controlled by the embedded controller. The loads are connected to the main line (TF1) and as well as to the TF2.
Initially TF1 is connected to the load, the loads run with this power. Due to any reason this power is interrupted, then it is identified by the controller and it immediately switches ON to the TF2 through the relay. The controller continuously monitors the TF1 (main line). When it finds the power on it again switches the loads connection to the main line. All the status of the transformers will be displayed on LCD.
BLOCK DIAGRAM EXPLANATION:
The above block diagram gives the overview of the project in the pictorial form with the help of the block diagram we will create pre model of the project and the analyze the function of the project the explanation of the project with block diagram over view is given as follows.
Power Supply Section:
This section is meant for supplying Power to all the sections mentioned above. It basically consists of a Transformer to step down the 230V ac to 18V ac followed by diodes. Here diodes are used to rectify the ac to dc. After rectification the obtained rippled dc is filtered using a capacitor Filter. A positive voltage regulator is used to regulate the obtained dc voltage.
This section forms the control unit of the whole project. This section basically consists of a Microcontroller with its associated circuitry like Crystal with capacitors, Reset circuitry, Pull up resistors (if needed) and so on. The Microcontroller forms the heart of the project because it controls the devices being interfaced and communicates with the devices according to the program being written.
In general, the ac line voltage present in your house wiring is not suitable for electronic circuits. Most circuits require a considerably lower voltage, while a few require higher voltages. The transformer serves to convert the ac line voltage to a voltage level more appropriate to the needs of the circuit to be powered. At the same time, the transformer provides electrical isolation between the ac line and the circuit being powered, which is an important safety consideration. However, a line transformer is generally large and heavy, and is rather expensive. Therefore, some power supplies (notably for PCs) are deliberately designed to operate directly from the ac line without a line transformer. The output of the transformer is still an ac voltage, but now of an appropriate magnitude for the circuit to be powered.
Analog to digital (A/D, ADC) converters are electrical circuit devices that convert continuous signals, such as voltages or currents, from the analog domain to the digital domain where the signals are represented by numbers.
LCD Display Section:
This section is basically meant to show up the status of the project. This project makes use of Liquid Crystal Display to display / prompt for necessary information.
This part of the system consists of current sensor. These sensor sense various parameters of load- current and are then sent to the Analog to Digital Converter.
In this project Relays are used to the Trip the transformer. A relay is an electrical switch that opens and closes under control of another electrical circuit. In the original form, the switch is operated by an electromagnet to open or close one or many sets of contacts