211 SRI RAMAKRISHNA MISSION VIDYALYA POLYTECHNIC COLLEGE.

  SCADA regulates traffic lights, controls traffic flow, and detects out-of-order signals. SCADA software applications are used to remotely monitor and control equipment related to pipelines, pumps, storage, offshore platforms and onshore wells, refineries and petro-chemical stations,  Electric power generation, transmission and distribution Electric utilities use RTUs (or PLCs) and HMI SCADA to detect current flow and line voltage of remote sites. They also use them to monitor the operation of breakers, and to take power grids on or off. SCADA systems can be found at electrical power distribution from gas-fired, coal, nuclear, electrical power transmission and distribution, etc. Water, wastewater and sewage State and municipal water use SCADA applications. They monitor and regulate water flow, reservoir levels, pipe pressure, wastewater collection and treatment facilities, water treatment centers and distribution, and other factors of the field devices. Buildings, facilities and envir

  SF6 Circuit Breaker: Sulphur Hexafluoride  or  SF6 circuit breaker  is a type of circuit breaker that uses pressurized SF6 (sulfur hexafluoride) gas to extinguish the arc. It is a dielectric gas having superior insulating and arc quenching properties far better than air or oil. It is used for arc quenching in high voltage circuit breakers up to 800 kV in power stations, electrical grids etc. SF6 gas has very high electronegativity. It has a strong tendency to absorb free electrons.T hen an arc is struck between the contacts, it absorbs the free electrons from it. It converts into negative ions which are heavier than electrons. Due to its heavyweight, its mobility is reduced. Therefore, the mobility of the charges in SF6 gas has low mobility which enhances the dielectric strength of the medium since the movement of charges is responsible for  current   flow.

  Stepper motor is brushless DC motor, which can be rotated in small angles, these angles are called steps. Generally stepper motor use 200 steps to complete 360 degree rotation, means its rotate 1.8 degree per step. Stepper motor used in many devices which needs precise rotational movement like robots, antennas, hard drives etc. We can rotate stepper motor to any particular angle by giving it proper instructions. Interfacing Stepper Motor with 8051 Microcontroller Interfacing with 8051 is very easy we just need to give the 0 and 1 to the four wires of stepper motor according to the above tables depending on which mode we want to run the stepper motor. And rest two wires should be connected to a proper 12v supply (depending on the stepper motor). Here we have used the unipolar stepper motor. We have connected four ends of the coils to the first four pins of port 2 of 8051 through the ULN2003A. 8051 doesn’t provide enough current to drive the coils so we need to use a  current driver IC

  Interfacing is one of the important concepts in  microcontroller 8051  because the microcontroller is a CPU that can perform some operation on a data and gives the output. However to perform the operation we need an input device to enter the data and in turn output device displays the results of the operation. Here we are using keyboard and LCD display as input and output devices along with the microcontroller. Interfacing is the process of connecting devices together so that they can exchange the information and that proves to be easier to write the programs. There are different type of input and output devices as for our requirement such as LEDs, LCDs, 7segment, keypad, motors and other devices. Here is given some important modules interfaced with microcontroller 8051. 1. LED Interfacing to Microcontroller: Description: LEDs are most commonly used in many applications for indicating the output. They find huge range of applications as indicators during test to check the validity of

  What is Schmitt Trigger? A Schmitt trigger is a comparator circuit that incorporates positive feedback producing two distinct switching thresholds. It was invented in 1934 by American scientist Otto Schmitt to reduce problems arising due to small input signal variations thresholding digital circuits. The main factors of a Schmitt trigger include: Hysteresis : It exhibits two different switching threshold voltages for the rising and falling signal edges due to positive feedback. Noise elimination : The hysteresis eliminates minor noise and fluctuations in the input signal. Square wave output : A Schmitt trigger converts analog signals like sine waves into clean digital square waves.

  Advantages/Disadvantages of a Three-Phase Transformer The advantages and disadvantages of a three-phase transformer are discussed below. Advantages of a three-phase transformer Needs less space to install and it is easier to install Less weight and reduced size Higher efficiency Low cost Transportation cost is low Disadvantages of a three-phase transformer The entire unit shuts down in case of fault or loss occurs in any one unit of a transformer as a common core is shared by all three units. Repair costs are higher Cost of spare units are high