AMIE Study Circle Blog

  Answer the following in brief (2 x 10)   Why Arcing ground should be avoided? A temporary fault creates an arc between an overhead line and ground. This arc extinguishes and restrikes in repeated and regular manner. This phenomenon is known as arcing ground, which is very common in ungrounded system and should be avoided. What is the function of d.c. reactor? This is used to improve the input power factor of the inverter power supply and reduce harmonics. Why is plug setting required? Selection of the required current setting is by means of a plug setting multiplier, which has a single insulated plug. While the plug is withdrawn for adjusting it to a different current setting during on-load condition, the maximum current tap is automatically connected, thus avoiding the risk of open circuiting the secondary of the C.T. under load condition. Explain the concept of speed governor. This is a fly-ball type of speed governor and constitutes the heart of the system as it senses the change

Discuss all the terms in brief (2 marks each):   Swing equation The Swing Equation of the generator describes the relative motion between the rotor axis and the synchronously rotating stator filed axis with respect to time. This equation is very helpful in analysing the stability of connected machines (machine here means generator).   It is given by   P s – P e = Md 2 δ/dt 2     P a = rotor accelerating power P s = shaft power  δ = Load Angle or Torque Angle M = angular momentum of generator rotor     Capital and running cost Capital cost . It includes the cost of the plant, land acquisition (unless a rent is paid, in which case this is a running cost), grid connection (although in some European states, the utility bears the cost), and initial financing costs (not repayment costs). Running cost . It is the cost which depends only upon the number of units generated. The running cost is on account of annual cost of fuel, lubricating oil, maintenance, repairs and salaries of operating

   Answer the following in brief: What do you understand by Skin Effect? Skin effect is a tendency for alternating current (AC) to flow mostly near the outer surface of an electrical conductor, such as metal wire.  The effect becomes more and more apparent as the frequency increases.   This phenomenon restricts the current to a small part of the total cross-sectional area and so has the effect of increasing the resistance of the conductor. Discuss the Proximity Effect. When the conductors carry the high alternating voltage, then the currents are non-uniformly distributed on the cross-section area of the conductor. This effect is called proximity effect.  The proximity effect results in the increment of the apparent resistance of the conductor due to the presence of the other conductors carrying current in its vicinity. Briefly discuss electromagnetic and electrostatic interference with communication lines. The "Electromagnetic effect" produces currents due to induction result

  Choose the correct option (2 marks each)   1. A power system will have greater flexibility of operation if they have ____ (a) Only Base load plants operating in combination (b) Various types of power plants operating in combination* (c) Only Peak load plants operating in combination (d) Only thermal power plants operating in combination Hint: If various types of power plants are operated in combination, the system will become more flexible i.e Steam and Nuclear power plants will supply base loads, Hydroelectric power plants will supply base or peak loads depending upon the availability of water, Gas turbine power plant will meet peak load demand and existing Diesel power plant will operate in emergency only.   2. For a given power system, its zero and maximum regulation will occur at the impedance angle of (a) 45* (b) 60  (c) 35  (d) 50 Hint: At θ = 45°, ZVR and maximum VR coincide.   3. A power system has a maximum load of 15 MW. Annual load factor is 50%. The reserve capacity of a

  Answer the following in brief (2 marks each) What is quality? Quality means that the products meet and exceed all requirements, standards and specifications. For example, certain industry products may need to meet specific standards and specifications for legal or medical reasons. State, two essential features of scientific management. Higher Productivity: Increase in the rate of production by use of standardized tools, equipment’s, methods and training of the workers. Cost Reduction: Reduction in the cost of production is done by rational planning and regulation, and cost control techniques.  What is meant by productivity? Productivity is commonly measured in output per worker or output per worker per hour. For a manufacturing company, a measure of productivity might be the number or value of the finished products each worker can produce within a given time. State the difference between "feed-forward" and "feedback control".  Feedback Control System : Feedback co

Displacement thickness and momentum thickness Displacement thickness . It is defined as the distance by which the external potential flow is displaced outwards due to the decrease in velocity in the boundary layer.   Momentum thickness . It is a measure of the boundary layer thickness. Momentum thickness is defined as the distance by which the boundary should be displaced to compensate for the reduction in momentum of the flowing fluid on account of boundary layer formation. Couette flow and Poiseuille flow Couette flow is the flow of a viscous fluid in the space between     two surfaces, one of which is moving tangentially relative to the other. The configuration often takes the form of two parallel plates or the gap between two concentric cylinders. The flow is driven by virtue of viscous drag force acting on the     fluid, but may additionally be motivated by an applied pressure gradient in the flow     direction. The Couette configuration models certain practical problems, like fl

Answer the following (4 marks each). Explain various components of gantry girder through neat sketches. The plate girder consists of the following components:    The web plate     Flange plate (addition of cover plate curtailed at proper sections)     Stiffeners like bearing stiffeners, longitudinal stiffeners, and intermediate stiffeners     Splices for flange plate and web plate     End connections Generally, gantry girders are supported on brackets connected to columns for lighter loads and are directly supported on columns for heavier loads.  A suitable seat is fabricated to support and connect the bottom flange of the gantry girder. The gantry girder is connected to the column near the top flange to provide lateral support and torsional restraint by channel sections.    Some of the typical sections are: Advantages of HSFG bolts over bearing bolts. The high strength bolts are also called high strength friction grip bolts. Briefly, these are called HSFG bolts. The high strength fric