問題一覧
1
Turbo alternators usually have
2 Poles
2
The protection from negative sequence currents is provided for
generators
3
the value of diversity factor is
greater than one
4
The turbine used for high head in hydro plant is
Pelton turbine
5
The per unit impedances of a transformer referred from the primary and secondary side
A. are equal
6
For load flow analysis transmission line are represented
nominal pi
7
The bus bar of the power system, whose voltage magnitude and angle is not known. is called
load bus
8
The zero sequence current in delta winding of Wye/Delta transformer is found
if neutral point of Y winding is earthed
9
The zero sequence current will not flow in the
L - L fault
10
One conductor open in a three phase transmission line will develop
a parallel connection of sequence networks,
11
The steady state stability limit of a two-machine system depends on
per unit reactance of the power system
12
a shunt fault is characterized by
increase in current reduction, frequency and pf
13
Most economic load on an overhead line is
greater than the natural load
14
The most economical load on an underground cable is
less than the surge loading
15
Capacitors with it as easily done with
C. Vacuum circuit breaker
16
In subsequent iteration, a voltage the controlled bus is treated as load bus when it's
Reactive power limit is violated
17
The voltage magnitude of a particular bus can be controlled by controlling the
B. Reactive power of the bus
18
Convergeance of the transmission load flow is always assured in case of
both A and C
19
For the stable operation of interconnected system, the passive element that can be used as interconnecting elements is.
reactor
20
The positive sequence component of the voltage at the point of fault is zero when it is a
three phase fault
21
Load flow study is carried out for
system planning
22
The main consideration for higher operating voltage of transmission is to
C. increase power transfer capability
23
If the effect of earth is taken into account, then the capacitance of line to ground
Increases
24
For a wye - delta transformer Y-side grounded, the zero sequence current
exist in the line on the Y-side
25
If real power demand is suddenly increased, frequency of the system will
decreases
26
taps of the transponder must be done at
high voltage
27
Fuse in motor provides
Short circuit protection
28
In grounding which is permitted as a grounding electrode I. Building metal frame II. Metal water pipe
both I & II
29
Which is not standards circuit rating
25 A
30
A circuit must be protected againts,
Overload, short-circuit, or leakage, voltage spikes
31
The location of the disconnecting means from the second building I. Disconnecting means must be located outside the second building on accessible location II. Disconnecting means must be located inside the entrance of the second building
Both I & II
32
What is the minimum clearance of service drop above the driveway
3700 mm
33
Thermal protection it's mainly use as ___ protection
Overload
34
What is the modern light sensor use in fax machine
Charged coupled device
35
What is/are the fundamental process of resistance welding
Heat and squeeze
36
In single phase, 3-wire system, the middle conductor must be which of the following
Grounded wire
37
How many three-way and four-way switches for a lighting system control in five different location
2-3 way & 3-4 way
38
___ is also known as "Cold standby reserve"
Back up reserve
39
Which of the following is included in the calculation reliability indices of distribution code?
34.5 kV line outages
40
What is the maximum voltage in dwelling unit
230 V
41
What is the minimum diameter of the ground rod
16 mm
42
What is the minimum size of underground service lateral conductor
8.0 mm² copper
43
Play electrode shall be installed of not less than ___ mm below the surface of the soil
750 mm
44
In the Philippine electrical code, the branch circuit permissible load is __ %
80
45
The main purpose bonding jumper is to connect equipment grounding conductors and ___ to the grounded conductor of the system
Service disconnect enclosure
46
In an alternating current circuit, the voltage lags the current. What element should be placed in parallel to the circuit to improve the power factor unity
Inductor
47
Which of the following is not considered exterior wall space in dwelling?
Sliding panel
48
What is the purpose of earthing
Prevent electric shock
49
A gas turbine power plant usually suits for
Peak load operation
50
Which of the following plant is expected to have the longer expected life
Steam
51
The purpose of the grid system is to
Interconnect the Power Station
52
One of the line parameters which is neglected in short transmission line is
Capacitance
53
The economical section of feeder can be obtained by applying
Kelvin's Law
54
Energy radiated continuously in the form of lighting waves is called
Luminous flux
55
The luminous intensity of a lamp is expressed in
Candela
56
The relative permeability of paramagnetic substance
Slightly greater than one
57
Which of the following has the highest value of relative permeability
Supermalloy
58
The torque of a synchronous motor when reach synchronism is called
Pull in torque
59
Month of March is the fire prevention, what is the electrical safety month
April
60
What angle will be illumination be halved to the object
60
61
Minimum thickness of concrete in a concrete in case electrode is
50 mm
62
The phenomenon of rise in voltage at the receiving end of the open circuited or lightly loaded line is called
Ferranti effect
63
what is the IEEE STANDARD DEVICE NUMBER FOR INSTANTANEOUS OVER CURRENT RELAY
50
64
Induction motor is running at rated load. what will happen when one winding of a delta connected motor is suddenly cut
will burn
65
Energy stored in an inductor is given by
1/2 LI^2 Joules
66
Which of the following is vector quantity
Magnetic field density
67
The two conductors of transmission line carry equal currrent (I) in opposite direction. the force on each conductor is
Proportional to I^2
68
The ratio of intensity of magnetization to the magnetization force is known as
Susceptibility
69
Paramagnetic materials have relative permeability
Slightly greater than one
70
The unit of magnetic flux is
Weber
71
Permeability in a magnetic circuit corresponds to an electric circuit
Conductivity
72
What is the standard device number for overvoltage relay
59
73
What is the standard device number for directional power relay
32
74
The unit of capacitance is
coulombs/volts
75
"The total electric flux through any closed surface surrounding charges is equal to the amount of charge enclosed". The above statement is associated with
gauss's law
76
Voltage across capacitor at any time t during charging from a DC source of voltage V is given by
v = V (1 - e^-t/λ)
77
The breakdown voltage for paper capacitors is usually.
200 to 1600 volts
78
The property of a material which opposes the creation of magnetic flux in it is known as
reluctance
79
The coefficient of self-inductance for a coil is given as
Nφ/I
80
"The mass of an ion liberated at an electrode is directly proportional to the quantity of electricity". The above statement is associated with
faraday's law of electrolysis
81
The power consumed in a circuit element will be least when the phase difference between the current and voltage is
90 degree
82
The commutator segments are connected to the armature conductors by means of
copper lugs
83
For a DC generator when the number of poles and the number of armature conductors is fixed, then which winding will give the higher emf?
B. wave winding
84
Iron losses in DC machine are independent variation in
load
85
Brushes of DC Machines are made of
carbon
86
No-load speed of which of the following motor will be highest?
series motor
87
If a DC motor is to be selected for conveyors, which motor would be preferred
Series motor
88
Small DC motors up to 5 HP usually have
2 poles
89
The mechanical power developed by shunt motor will be maximum when the ratio of back EMF applied voltage is
0.5
90
The no-load current drawn by transformer is usually what percent of the full load current
2 to 5 percent
91
Dielectric strength of transformer oil is expected to
33kV
92
The maximum efficiency of a distribution transformer is
at 50% full load
93
The frequency of the voltage generated in large alternators
50 Hz
94
Harmonic component of generated EMF will be more in
Full pitch coil
95
The dark and bright lamp method is used for
Synchronizing
96
An alternator driven by a Francis hydraulic turbine is a ….... alternator?
low or medium speed
97
For low head and high discharge, the hydraulic turbine used is
Kaplan turbine
98
Which device is used to chane the kW output of generators in parallel?
Governor
99
Which motor is used in food mixer
universal motors