In case of D.C. machines, mechanical losses are primary function of speed.
Last Answer : Iron losses in a D.C. machine are independent of variations in load.
Last Answer : In a D.C. generator, the iron losses mainly take place in armature rotor.
Last Answer : The total losses in a well designed D.C. generator of 10 kW will be nearly 500 W.
Losses which occur in rotating electric machines and do not occur in transformers are?
Last Answer : Friction losses windage losses
Briefly explain how an electrical generator converts mechanical energy into electrical energy.
Last Answer : Working principle of DC generator: * Working principle of DC generator is the principle of dynamically induced emf or electromagnetic induction. * According to this principle, when flux is cut by a conductor, an ... , the flux is cut by the armature winding and an emf is dynamically induced in it.
Explain the suitability of aluminium as an electrical conductor with respect to its mechanical and electrical properties.
Last Answer : Following are requirements of conductor:- i) High conductivity : Material should have high conductivity, So that * cross section of conductor (size) reduces, * Copper losses reduces, * So Efficiency ... . Boiling point is 1820°C 9. Specific gravity is 2.7 10. High resistance to corrosion.
Define natural, mechanical, forced and induced draught systems.
Last Answer : Natural draught system: - When the fuel is burnt (combustion) in the furnace due to natural circulation of air, the draught is called natural draught. Mechanical draught system: - In a mechanical ... combustion. OR If fan/blower is placed after the furnace then it is called as induced draught
Explain the mechanical properties of insulating materials.
Last Answer : i) Mechanical strength: Mechanical strength depends on temperature and humidity. a) Temperature: High temperature badly affects the mechanical strength of insulating material. While selecting material ... material should have property of easy moulding and machined into required shape and size.
Which of the following converts linear displacement from a mechanical reference into a proportional electrical signal containing phase and amplitude information? A) CRO B) LVDT C) RVDT D) None of these
Last Answer : Which of the following converts linear displacement from a mechanical reference into a proportional electrical signal containing phase and amplitude information? A) CRO B) LVDT C) RVDT D) None of these
In Torque-Voltage analogy, the Moment of Inertia of a mechanical rotational system is analogous to (A) Capacitance C. (B) Inductance L. (C) Resistance R. (D) Inductive reactance XL
Last Answer : In Torque-Voltage analogy, the Moment of Inertia of a mechanical rotational system is analogous to Inductance L.
In a d.c. motor, the mechanical output power actually comes from?
Last Answer : In a d.c. motor, the mechanical output power actually comes from electrical input power.
The mechanical power developed by the armature of a d.c. motor is equal to?
Last Answer : The mechanical power developed by the armature of a d.c. motor is equal to armature current multiplied by back e.m.f.
Last Answer : The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is 0.5.
Last Answer : As hysteresis motors are free from mechanical and magnetic vibrations therefore these are considered as suitable for sound equipment.
The synchronous motor which works on leading power factor and does not drive any mechanical load is called?
Last Answer : The synchronous motor which works on leading power factor and does not drive any mechanical load is called synchronous condenser.
State the losses in secondary distribution system.
Last Answer : The losses in secondary distribution system: a) Technical losses: 1. Due to poor voltage 2. Due to unbalance load 3. Due poor quality of transformer & its components 4. Due to poor quality ... of induction type of energy meter. 3. Lack of administration. 4. Energy theft 5. Unmetered supply
Explain the “mitigation of power theft” and “faulty meter replacement” for energy conservation techniques to reduce commercial losses.
Last Answer : Energy conservation techniques to reduce commercial losses: 1. Mitigation of Power Theft: Power theft being the most important issue which all of the service providing utilities ... agricultural sector. Prepaid meters may prove effective measures against unauthorized abstraction of energy.
Explain following techniques related to energy conservation in transmission and distribution system. (i) By balancing phase currents (ii) Variable technical losses (I2R losses).
Last Answer : (i) Balancing Phase currents: Proper (healthy balanced) three phase loads always draw equal currents in all lines but single phase loads in the 3 phase 4 wire system or loads connected between two ... . 11) Minimize I2R losses. 12) Balance the load currents. 13) Regulate the system voltages.
The friction losses in Real Transformers are : (A) 0% (B) 5% (C) 25% (D) 50%
Last Answer : A
Which of the following can reduce the Eddy current losses? A) By making the core of a stack of plates electrically insulated from each other B) By making the core of solid block C) By increasing the applied voltage D) None of these
Last Answer : Which of the following can reduce the Eddy current losses? A) By making the core of a stack of plates electrically insulated from each other B) By making the core of solid block C) By increasing the applied voltage D) None of these
In DC motor iron losses are occurred in?
Last Answer : In DC motor iron losses are occurred in the armature.
Reduction in core losses and increase in permeability are obtained with transformer employing?
Last Answer : Reduction in core losses and increase in permeability are obtained with transformer employing core built-up of laminations of cold rolled grain oriented steel.
In a given transformer for a given applied voltage, losses which remain constant irrespective of load changes are?
Last Answer : In a given transformer for a given applied voltage, losses which remain constant irrespective of load changes are hysteresis and eddy current losses.
Auto-transformer makes effective saving on copper and copper losses, when its transformation ratio is?
Last Answer : Auto-transformer makes effective saving on copper and copper losses, when its transformation ratio is approximately equal to 1.
In a synchronous motor which losses varies with load?
Last Answer : In a synchronous motor, copper losses varies with load.
Explain the electrical losses of magnetic materials used for the cores of inductors and transformer.
What are the losses in a transmission line?
What are the types of power losses in inductor?
Last Answer : Copper losses, Eddy current loss, and hysteresis loss are the types of power losses in inductor.
What is the percentage of stray losses in DC machine?
Last Answer : Percentage of stray losses in DC machine is about 1 % .
In synchronous motor, does the winding losses vary with load?
Last Answer : No, in the synchronous motor the winding losses do not vary with load.
Last Answer : Iron loss, copper loss and mechanical losses these are the losses in DC machine.
Explain the on state losses in power BJT.
Last Answer : On state losses in power BJT: Transistor have four types of losses one is turn on state losses second is turn off state losses third is turn on switching losses and fourth is turn ... ON = VCE sat x IC With increasing collector current collector to emitter saturation voltage increases.
In case of D.C. machines, mechanical losses are primary function of (a) current (b) voltage (c) speed (d) none of above
Last Answer : Ans: c
Is not asked
Why does my computer (Mac OSX) grumble when it's working?
Last Answer : answer:Hunger pangs? Bad hair day? Wants to go to the beach? Osteoarthritis? What’s the actual machine? Desk top? Lap top? How old? Which OS? The latest is 10.8.4, I think. Or it was a minute ago.
What is the difference between basic hole and basic shaft ?
Last Answer : A basic hole is one whose lower deviation is zero and in case of basic shaft the upper deviation is zero.
What is the percentage of carbon in cast iron ?
Last Answer : 2.5%.
Anyone care to join me in a quiet prayer for Jeret "Speedy" Peterson?
Last Answer : Not to sound cold, but it won’t help at this point.
Last Answer : Satisfactory commutation of D.C. machines requires brushes should be of proper grade and size, brushes should smoothly run in the holders, smooth, concentric commutator properly undercut.
Last Answer : For a D.C. machines laboratory following type of D.C. supply will be suitable induction motor D.C. generator set.
Last Answer : Brushes of D.C. machines are made of carbon.
Last Answer : The purpose of retardation test on D.C. shunt machines is to find out stray losses.
The design of mechanical parts is particularly important in case of _____ speed machines. (a) low (b) medium (c) high (d) any of the above
Last Answer : (c) high
Last Answer : In a D.C. generator the number of mechanical degrees and electrical degrees will be the same when number of poles is 2.
A machine's output is 4000 joules and its frictional losses are 1000 joules. Which of the following is its efficiency? Is it: w) 25% x) 30% y) 75% z) 80%
Last Answer : ANSWER: Z -- 80%
Hysteresis losses in electrical machines is equal to a. B1.2max f b. B1.6max f c. B1.2min f d. B1.2max fmin
Last Answer : Hysteresis losses in electrical machines is equal to a. B1.2max f b. B1.6max f c. B1.2min f d. B1.2max fmin
In electronic fuel injection, there is improvement in the _____________ efficiency due to comparatively less resistance in the intake manifolds which will cause less pressure losses. a) mechanical b) volumetric c) overall d) none of the mentioned
Last Answer : Answer: b Explanation: In electronic fuel injection, there is improvement only in the volumetric efficiency due to comparatively less resistance in the intake manifolds which will cause less pressure losses and no other efficiencies are hindered.
The mechanical splice is best suited for ∙ A. quicker installation under ideal condition ∙ B. minimum attenuation losses ∙ C. field service conditions ∙ D. situations in which cost of equipment is not a factor
Last Answer : D. situations in which cost of equipment is not a factor
Total mechanical losses ( frictional losses , pumping loss in intake and exhaust and power accessories) will amount to a.10-20 % ihp b.2-10 % ihp c.20-30 % ihp d.30 -50 % ihp
Last Answer : a.10-20 % ihp