Description : Iron losses in a D.C. machine are independent of variations in (a) speed (b) load (c) voltage (d) speed and voltage
Last Answer : Ans: b
Description : Brushes of D.C. machines are made of (a) carbon (b) soft copper (c) hard copper (d) all of above
Last Answer : Ans: a
Description : A separately excited generator as compared to a self-excited generator (a) is amenable to better voltage con-trol (b) is more stable (c) has exciting current independent of load current (d) has all above features
Last Answer : Ans: d
Description : Copper brushes in D.C. machine are used (a) where low voltage and high currents are involved (b) where high voltage and small cur-rents are involved (c) in both of the above cases (d) in none of the above cases
Description : In D.C. generators, current to the external circuit from armature is given through (a) commutator (b) solid connection (c) slip rings (d) none of above
Last Answer : In case of D.C. machines, mechanical losses are primary function of speed.
Description : The insulating material used between the commutator segments is normally (a) graphite (b) paper (c) mica (d) insulating varnish
Last Answer : Ans: c
Description : The material for commutator brushes is generally (a) mica (b) copper (c) cast iron (d) carbon
Description : In a four-pole D.C. machine (a) all the four poles are north poles (b) alternate poles are north and south (c) all the four poles are south poles (d) two north poles follow two south poles
Description : In lap winding, the number of brushes is always (a) double the number of poles (b) same as the number of poles (c) half the number of poles (d) two
Description : In a commutator (a) copper is harder than mica (b) mica and copper are equally hard (c) mica is harder than copper (d) none of the above
Description : 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
Description : During short circuit test iron losses are negligible because A. The current on secondary side is negligible B. The voltage on secondary side does not vary C. The voltage applied on primary side is low D. Full-load current is not supplied to the transformer
Last Answer : C) the voltage applied on primary side is low
Description : 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%
Description : 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
Description : Losses which occur in rotating electric machines and do not occur in transformers are?
Last Answer : Friction losses windage losses
Description : 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.
Description : 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
Description : 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
Description : Line losses in a distribution circuit are kept to a minimum by __________. A. adding rubber insulation conductors to the circuit B. using higher current and lower voltage C. increasing the number of thermal relays in the circuit D. using higher voltage and lower current
Last Answer : Answer: D
Description : In actual machines a.Mechanical advantage is unity b.Mechanical advantage is greater than velocity ratio c.Mechanical advantage is less than velocity ratio d.Mechanical advantage is less than unity e.Mechanical advantage is equal to velocity ratio
Last Answer : c. Mechanical advantage is less than velocity ratio
Description : What are the energy transfers of the six simple machines for example an incline plane is gravitational potential energy to mechanical energy. I want to know what are the other fives and for levers I would like to know class one and class 2?
Last Answer : \Delta E\Delta t\geq
Description : In actual machines (A) Mechanical advantage is greater than velocity ratio (B) Mechanical advantage is equal to velocity ratio (C) Mechanical advantage is less than velocity ratio (D) Mechanical advantage is unity
Last Answer : (C) Mechanical advantage is less than velocity ratio
Description : In ideal machines (A) Mechanical advantage is greater than velocity ratio (B) Mechanical advantage is equal to velocity ratio (C) Mechanical advantage is less than velocity ratio (D) Mechanical advantage is unity
Last Answer : (B) Mechanical advantage is equal to velocity ratio
Description : You are attempting to parallel two AC generators and the synchroscope pointer stops at a position other than 0°. If you close the circuit breaker at this moment _____________. A. the incoming ... hazardous condition will be created by the incoming machine being at a higher frequency than the bus
Last Answer : Answer: C
Description : A transformer in an electric circuit serves to ____________. A. generate its own electrical power B. transform electrical energy into mechanical energy C. increase or decrease circuit voltage as required D. convert AC current to DC current
Description : Which of the following precautions should be taken when troubleshooting various power circuits using a common solenoid-type mechanical voltage tester (wiggins)? A. Never use this tester on circuits greater ... voltage expected in the circuit in order to prevent damage from an off-scale reading.
Last Answer : Answer: A
Description : Speaker is a device that __________. A. convert current variations into sound waves B. none of these C. convert electrical energy to mechanical energy D. convert sound waves into current and voltage
Last Answer : A. convert current variations into sound waves
Description : main function of the current regulator is A. To prevent the reversal flow of current from the battery when dynamo speed is drops. B. To safeguard against flow of high currents to battery when armature develops ... . C. To prevent building up of high voltage in a circuit. D. None of the above
Last Answer : B. To safeguard against flow of high currents to battery when armature develops more current.
Description : The full torque electric brake on an electric cargo winch functions to _____________. A. act as a backup brake in the event the mechanical brake should fail B. automatically hold the load ... automatically govern the lowering speed of the load D. automatically govern the hoisting speed of the load
Last Answer : Answer: B
Description : For a shortened vertical antenna, where should a loading coil be placed to minimize losses and produce the most effective performance? A. As low as possible on the vertical radiator B. Near the center of the vertical radiator C. As close to the transmitter as possible D. At a voltage node
Last Answer : B. Near the center of the vertical radiator
Description : The power transmitted will be maximum when (a) corona losses are minimum (b) reactance is high (c) sending end voltage is more (d) receiving end voltage is more
Last Answer : (c) sending end voltage is more
Description : Explain the following energy conservation techniques: (i) By reducing I2R losses in Trans. system (ii) By optimizing distribution voltage.
Last Answer : i) By reducing I2R losses in Trans: 1. Opting for low resistance All Aluminum Alloy conductors (AAAC) in place of conventional aluminum cored steel reinforced (ACSR) lines. 2. ... line power losses. Thus maintaining the voltages at the specified levels leads to energy savings/conservation.
Description : 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.
Description : Justify. Power MOSFET is operated at high enough gate source voltage to minimize the conduction losses.
Last Answer : MOSFET is metal oxide field effect transistor. MOSFET is a voltage controlled device. MOSFET is majority carrier device. MOSFET are of two one is n-channel MOSFET and p-channel MOSFET. Gate, ... . Hence, power MOSFET is operated at high enough gate-source voltage to minimize the conduction losses.
Description : Mark the correct option related to submission of robbery report to DG Posts a) Case of highway robbery of mail involving loss of cash/valuables above Rs 50000 b) The attacks on offices by dacoits ... ) Cases of fraud and loss or misappropriation of public money exceeds Rs 50000 e) All the above
Last Answer : e) All the above
Description : In case of Venturimeter, friction losses are about __________ percent of maximum velocity head. (A) 2 (B) 8 (C) 12 (D) 20
Last Answer : (A) 2
Description : Pick out the wrong statement: (A) Greater is the kinematic viscosity of the liquid, greater is the thickness of the boundary layer (B) Blowers develop a maximum pressure of 2 atmospheres ( ... factor in case of turbulent flow of liquids in pipe depends upon relative roughness & Reynolds number
Last Answer : (C) Friction losses in pipe fittings are generally expressed in terms of velocity heads
Description : In case of flow through parallel pipes, (A) The head loss for all the pipes is same (B) The total discharge is equal to the sum of discharges in the various pipes (C) The total head loss is the sum of head losses in the various pipes (D) Both (A) and (B)
Last Answer : Answer: Option D
Description : The primary advantage of automatic vending as a form of retailing is that : 1. it provides continuous service to customers 2. it eliminates the need for sales personnel 3. vending machines require little maintenance 4. it offers low cost, personal method of selling 5. none of these
Last Answer : it eliminates the need for sales personnel
Description : The primary advantage of automatic vending as a form of retailing is that: A)it provides continuous service to customers. B)it eliminates the need for sales personnel. C)vending machines require little maintenance. D)it offers a low cost, personal method of selling.
Last Answer : B)it eliminates the need for sales personnel.
Description : Why Does Curving The Pole Faces In A Dc Machines Contributes To A Smoother Dc Output Voltage From It?
Last Answer : For having smoother output voltage from DC machines its commutation must be as ideal as possible. In order to have good commutation the flux density in the air gap must decrease gradually from maximum value under the center of the pole to zero on.
Description : Which of the following is not a source of ozone emission in the atmosphere? (A) Refrigerators (B) Xerox machines (C) Dermatological photo-therapy equipments (D) High voltage electrical equipments
Last Answer : (A) Refrigerators
Description : The advantage(s) of the method of D.C. motor speed control shown in the illustration is/are ______________. EL-0101 A. elimination of armature starting resistor losses B. elimination of speed instability with variable loads C. the ease of reversing motor direction D. all of the above
Description : A 3-phase 50HZ SCIM takes a power input of 30 KW at its full load speed of 1440 rpm. Total stator losses are 1 KW. The slip and rotor ohmic losses at full load are a) 0.02, 600 W b) 0.04, 580 W c) 0.04, 1160 W d) 0.04, 1200 W
Last Answer : Ans: 0.04, 1160 W
Description : A load with an impedance of 440 ohms is connected across the secondary of the transformer illustrated. If the input voltage is 110 VAC and the step-up ratio is 10 to 1, what will be the primary current? EL-0055 A. 2.5 amps B. 25 amps C. 250 amps D. current cannot be determined with information given
Description : A load is connected to the secondary of the transformer illustrated and the current through the load is 10 amps. If the step-up ratio is 10 to 1 and the input voltage is 110 VAC, what will be the current flow through the primary? EL-0055 A. 1 amp B. 10 amps C. 100 amps D. 1000 amps
Description : Which of the following statements is true concerning stepdown transformer operation? A. The inductance on the primary side is the same as the inductance on the secondary side. B. The voltage to the primary ... . D. The voltage to the primary side is greater than the voltage from the secondary side.
Description : If the illustrated device has a step-up ratio of 10 to 1 what voltage be measured at the secondary shortly after the primary of the device is connected to 110 volts DC with a current of 12 amps? EL-0055 A. 0 volts B. 110 volts C. 1000 volts D. 1100 volts