51. The voltmeter shown in the circuit reads ?
52. The ratio of conductor voltage and the voltage across the disc nearest to the conductor multiplied by number disc's is ?
The string efficiency is defined as the ratio of voltage across the string to the product of the number of strings and the voltage across the unit adjacent string.
String efficiency = Voltage across the string / (number of discs X voltage across the disc nearest to the conductor).
Greater the string efficiency, more uniform is the voltage distribution .
53. The meter constant of an energy meter will be given in ?
The meter constant of an energy meter will be given in revolutions/kWh.
Meter constant = Number of revolutions / kWh
Thus the number of revolutions of the disc per kWh of enery consumption is called the meter constant.
54. In an AC network, the load connected is (10 + j10). The phase relation between the voltage applied and the current through the load is ?
Given Z =(10+j10)
compare with this Z =R +jx
R = 10 ohm
and
Z = √($10^2$+$10^2$) = √(100x2) = 10√2
Power Factor Cosθ = R/Z
Cosθ =10/10√2 = 1/√2 = Cos 45° (voltage leads current by 45° or Current lags voltage by 45°)
55. When the supply to the excitation fails, the synchronous generator acts like a/an ?
If excitation of synchronous generator fails it acts as
When the excitation is lost the magnetic coupling of the rotor with the rotation field of the stator is lost and as the mechanical input power is still there the roror speeds up and causes the synchronous generator to become an asychronous generator or induction generator..
56. An electric motor in which both the rotor and stator fields rotate with same speed is called ?
A synchronous motor is one in which the rotor normally rotates at the same speed as the revolving field in the machine.
57. Which of following lamps employs a bimetallic strip ?
A bimetallic strip is used to convert a temperature change into mechanical displacement.
... The curvature of a bimetallic beam can be described by the following
... as a patio thermometer or a meat thermometer), uses a bimetallic strip wrapped into
... thermal flashers for older turn signal lamps, and fluorescent lamp starters.
58. Two bulbs of rating 230V, 60 W and 230 V, 100 W are connected in parallel across supply mains. Identify the correct statement. 230V, 60 W ?
For parallel connection The 100 W bulb will glow brighter PROOF:
As individually calculating resistance of each bulb from formula :
R=$V^2$/P
U will get higher resistance value for low rated bulb.
Since, Bulbs are connected in parallel And current in parallel not same, so brightness will be directly proportional to $I^2$*R.
Hence bulb of higher rating will be more brighter for parallel connection.
For series connection 60W will glow brighter than 100W.
PROOF:
As individually calculating resistance of each bulb from formula :
R=$V^2$/P
U will get higher resistance value for low rated bulb.
Since, Bulbs are connected in series And current in series remains same, so brightness will be directly proportional to $I^2$*R.
Hence bulb of lower rating will be more brighter for series connection.
59. If an alternator is operating at unity power factor, then its terminal voltage is ?
In an alternator, voltage regulation will be positive when power factor of the load is unity & lagging.
Zero Voltage Regulation and negative voltage regulation will be positive when power factor of the load is Leading.
60. A shaded pole motor is basically a___ motor ?
The shaded pole motor is simply a self-starting single-phase induction motor whose one ... The shaded pole motor rotates only in one particular direction, and the ... They are suitable for small devices like relays and fans because of its low cost .
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