Electrical Engineering

" Power system stability is the ability of an electrical power system, for a given initial operational condition,to regain  a state of operating equilibrium after being subjected to a physical disturbance ,with most system variables bounded so that physically the entire system   remains intact "   P ower system engineering forms a vast and major portion of electrical engineering studies. It is mainly concerned with the production of electrical power and its transmission from the sending end to the receiving end as per consumer requirements, incurring minimum amount of losses. The power at the consumer end is often subjected to changes due to the variation of load or due to disturbances induced within the length of transmission line. For this reason the term power system stability is of utmost importance in this field, and is used to define the ability of the of the system to bring back its operation to steady state condition within minimum possible time after h

An overhead power line is a structure used in electric power transmission and distribution to transmit electrical energy along large distances. It consists of one or more conductors (commonly multiples of three) suspended by towers or poles. Since most of the insulation is provided by air, overhead power lines are generally the lowest-cost method of power transmission for large quantities of electric energy. Towers for support of the lines are made of wood (as-grown or laminated), steel (either lattice structures or tubular poles), concrete, aluminum, and occasionally reinforced plastics. The bare wire conductors on the line are generally made of aluminum (either plain or reinforced with steel, or composite materials such as carbon and glass fiber), though some copper wires are used in medium-voltage distribution and low-voltage connections to customer premises. A major goal of overhead power line design is to maintain adequate clearance between energized conductors and

  Voltage to Time A/D converter (Ramp type) Any digital voltmeter has a fundamental cycle sequence which involves sampling, display, and reset sequence. The application of input voltage initiates the measurement cycle. The oscillator is automatically switched with the operator and its output consists of pulses which are counted by an electronic counter. A units counter is first actuated. This units counter provides a carry pulse to the tens counter on using the counter input pulse. In turn, the tens counter provides its own carry pulse after it has counted 10 carry pulses from the units counter. If excess input voltage is being measured, it provides its own carry pulse which switches on a warning lamp. Each decade counter unit in a DVM is counted as a D to A converter. Outputs of a D to A convertor are connected in parallel which build up a comparison voltage. At the instant when the comparison section senses that the input voltage and comparison voltages are eq