31-07-2012, 12:01 PM
AUTOMATIC POWER GRID CONTROLLER
AUTOMATIC POWER.doc (Size: 105.5 KB / Downloads: 89)
Introduction:
Automation of systems has become the demand of the day. Newer technology has made everything automatic and self repairable. In fact most of the developed systems are impossible to be controlled by human beings. There are many advantages of automation, first and most common human errors are eliminated, speed of operation becomes very fast and most advantageous is that the cost gets reduced. In this project we are controlling a power grid and different units are controlled on the basis of time.
Description:
The working of the system can be described as shown below.
We will be using serial com of the PC to control different relays.
For the sake of simplicity, we will control only four relays. It can be extended according to the requirements. Controlling variable is time. In the duration of 24 hours, we will allot different time slots to each unit. On proper time, the relays will be activated automatically and corresponding unit will get activated. The functioning direction is shown below.
Software:
In software we shall use VB interfacing to control the serial port. It provides easy method to implement a graphical user interface. MS comm. 6.0 will be used to control the serial port. It has inbuilt control over serial port. Only parameters are reacquired to be configured.
Hardware:
Microcontroller is the central part of the hardware. In serves two purposes, first it controls the serial communication and secondly it controls the relays. Other parts include optocouplers, relay driver and relays.
ULN 2803:
The eight NPN Darlington connected transistors in this family of arrays are ideally suited for interfacing between low logic level digital circuitry (such as TTL, CMOS or PMOS/NMOS) and the higher current/voltage requirements of lamps, relays, printer hammers or other similar loads for a broad range of computer, industrial, and consumer applications. All devices feature open–collector outputs and freewheeling clamp diodes for transient Suppression. The ULN2803 is designed to be compatible with standard TTL families while the ULN2804 is optimized for 6 to 15 volt high level CMOS or PMOS.