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Showing posts with the label Electrical & Instrumentation

Questions & Answers on Power Transformers

    1-What do you mean by power transformer? It is a static Electro-magnetic machine which transforms alternating current from one AC voltage to another AC voltage at same frequency & at the same apparent power (KVA). 2-What is the principle of Power transformer operation? Power transformers work on the principle of electromagnetic induction. Which states that, EMF induced in a closed conducting circuit when the magnetic flux linking with that circuit changes in time. 3-What is the main function of a power transformer? Generally it is used for stepping up or stepping down of Voltage to desired level 4-What are the various parts of power transformer? General arrangement of Power Transformer Casing Core Primary & secondary windings LV & HV bushings Radiators & cooling system Conservator Breather Protection devices like Buchholz relay, relief valves, temperature sensors 5-Why does the oil conservator is placed at higher elevation? Oil conservator is placed at a slightly hi

Batteries & troubleshooting

   1-List down the applications of auxiliary DC power supply system in Power plants?   Protections relays Circuit breakers DCS Trip circuits Signaling Telephone system & communication Emergency lighting Transmitters & Positioners Emergency oil pumps Metering panels 2-List down the various DC voltages & their applications in power plants Sl No. Voltage Applications 1 220 VDC & 110 VDC Protection system Emergency lighting Trip & closing coil of circuit breakers Operating mechanisms 2 48 VDC Telephone communication 3 +/- 24 VDC Control circuits Measuring instruments Static relays 3-What is the power source for DC supply? Main power source is lead-acid storage battery & AC/DC rectifier set 4-What are the installation requirements for lead acid battery ? The room should be isolated from other system Room should have adequate lighting & venti

Questions Answers on basics of instrumentations for Power plant Mechanical Engineers

1. What is an instrumentation? Instrumentation is the art of measuring a value of plant parameters. Or The technology which is used to measure and control the process system of plant is called instrumentation. 2. What is an instrument? An instrument is a device that transforms a physical variable of interest (the measurand) into a form that is suitable for recording (the measurement). 3. What is measurand? A physical quantity, property, or condition being measured. Often, it is referred to as a measured value. 4. What is a sensor? The portion of a measurement system that responds directly to the physical variable being measured. 5. What are the various variables measured in a power plant? Pressure, temperature, force, speed, frequency, current, voltage, resistance, time, displacement, acceleration, light intensity, density, pH, conductivity, flow etc. 6. What is calibration of a sensor? The relationship between the physical measurement variable input and the