Font size
WorksheetsPOWER PLANT
Total questions: 199
Worksheet time: 2hrs 40mins
What do you call the protective angle between the Overhead ground wire and the power cable in the Transmission tower
shielding angle
surge angle
clearing angle
arcing angle
Disconnecting switch is provided for proper protection of electric substations and power plant. What is its main function.
for protection of circuit breaker
for maintenance purpose
to break the system under fault
for complete isolation
The highest magnitude of fault current will determine the size of _________, while the lowest magnitude will determine the size of_____________.
fuse, relay
circuit breaker, isolator
circuit breaker, relay
relay, circuit breaker
The PTs of a 220 kV transmission line have ratio of 132.76 kV: 66.375 V and are connected wye-wye. A voltmeter connected line to ground reads 66 V, what is the transmission line voltage?
223.15 kV
220.10 kV
228.63 kV
225.25 kV
The transfer bus scheme has the following characteristics EXCEPT one. Which one of this?
It allows better continuity of service as compared with the single bus
It allows the disconnection of circuit breakers for maintenance without Interrupting the service
It is more flexible
It is more costly than that of the single bus system
It is more costly than that of the single bus system
Even with a circuit breaker failure, a station shutdown will not result.
It gives more flexibility
It reduces the likelihood of extended outages of any circuit due to circuit breaker trouble
It permits breaker maintenance without feeder outage.
A large electric power distribution system is protected against surges and faults by
high-speed relays detecting the trouble
protective gaps crossing drain cells
protective relays operating without a time delay
radio communication system using flow frequency
Which of the following steps is used for isolating a circuit breaker for maintenance purposes?
pull the substation fuses
turn off the main generator
open the disconnect switches
ground the auxiliary contacts
In a generating and distribution system, current balance is provided by protective zones which are
monitored by differential relays
used to eliminate reflections on short transmission lines
used to trip all circuit breakers in the system
isolated during fault by disconnect switches
For protection of parallel feeders fed from one end the relays required are:
Directional relay at both the ends.
Non-directional relays at the source end and directional relays at the load end
Directional relays at the source end and non-directional at the load end.
Non-directional relays at both the ends
If a fixed amount of power is to be transmitted over a certain length with fixed power loss, it can be said
the volume of the conductor required is proportional to voltage only
the volume of the conductor is inversely proportional to voltage and that of power factor of load
the volume of conductor required is inversely proportional to the square of voltage and that of the power factor of load
the volume of the conductor is proportional to square of the voltage and directly proportional to power factor of load
Assuming the constant efficiency transmission, if the voltage is increased n times, the size of the conductor would be
reduced to 1/n2 that of the original
reduced to 1/n that of the original
increased to n2 that of the original
increased to n times that of the original
In a distribution system, if the synchronous capacitors are to be used for improving the power factor, the correct location would be
at the receiving end
at the sending end
in middle of the transmission line
none of the above
In limiting case, the maximum cost of the phase advancing plant that would justify its installation is when its working cost is
less than the working cost of generating plant to give the same increase in power
equal to working cost of the generating plant to give the less increase in power
equal to the working cost of generating plant to give the same increase in power
greater than the working cost of the generating plant to give more increase in power
The synchronizing power developed in the parallel operation of the alternators will be maximum when
the armature reactances equal to their resistances
the armature have less reactances than their resistances
the armature have more reactances than their resistances
the resistances of armatures are zero
The actual division of the total kW load between alternators in power plant running in parallel depends upon the
voltage-load characteristic
a and b both
speed-load characteristic
a or b
Natural Uranium contains
50% U235
0.7% U235
0.7% U235
100% U235
Which of the following will affect the transfer of the real power between the stations if they are interconnected?
Reactance
In-phase voltage boost
Quadraturel voltage
angular displacement between stations
The size of the feeder is determined primarily by
the voltage across the feeder
the percentage variation of voltage in the feeder
the current it is required to carry
the distance over which the transmission is made
If the voltage is increased n times, the current in the feeder is reduced to (for a given power delivered)
sqr root n times of the original
1/n times of the original
1/n^2 times of the original
1/ sqr root n times of the original
In the d.c. three wire transmission system the cross-section of the neutral is generally
⅓ of the outer conductors
½ of the outer conductors
¼ of the outer conductors
equal to the outer conductors
The Metal clad is related to
Amplidyne
Switchgear system
Synchros
Relays
The power transmission capacity of the transmission line is
inversely proportional to the square of the voltage
inversely proportional to the voltage
proportional to the square of the operating voltage
proportional to the voltage
Which of the following power plant has the maximum efficiency?
MHD
Atomic Reactor
Hydro-electric power plant
Thermal power plant
The reactors used in most power station specially in HVDC is to limit the short circuit current in the alternators have very small resistance in comparison to reactance
to improve power factor
because the high resistance will not help to limit the short circuit current
to avoid the energy waste
because the high resistance will raise the temperature and insulation of reactor will be spoiled
The earthing transformer is used
to provide artificial neutral earthing where the neutral points of the three phase system are not accessible
to avoid the harmonics in the transformers
to improve the current capacity of the neutral wire
none of the above
To protect the power transformer (Y-Y, with neutral earthed) in power station against fault, the current transformer will have
Delta-delta connection
Star-star connection
Star-delta connection
Delta-star connection
To protect the power transformer (Delta-delta) against fault, the current transformer will have
Delta-delta connection
Star-star connection
Delta-star connection
Star-delta connection
Which of the following power system distribution gives the greater reliability?
ring system of the distribution
radial system of the distribution
D.C. three wire system of the distribution
A.C. three phase four wire system
The diversity factor is defined as the
Average demand / Maximum demand
Sum of consumers maximum demand / Maximum load on the station
Maximum load on the station / Sum of consumers maximum demand
Average demand / Maximum load on the station
The power intended to be available even under emergency condition is called
spinning reserve
firm power
cold reserve
hot reserve
Which of the following generating stations has the minimum running cost?
Nuclear power station
Thermal power station
Diesel power plant
Hydro-electric station
Overfluxing protection is recommended for
auto-transformer of the power plant
Distribution transformer
generator transformer of the power plant
station transformer of the power plant
Which of the following statements is true if restricted earth fault protection is provided to star winding of the generator transformer
in fact CTs are not required at all as the fault current is not very high
one CT is provided in the neutral
one Ct in each phase and fourth in the neutral are provided and their secondaries are connected in parallel
two CTs are provided, one in R-phase and other Y phase with a CT in neutral
in fact CTs are not required at all as the fault current is not very high
improve impedance
compensate line capacitive reactance
compensate line inductive reactance
improve line voltage
High water level of a boiler drum can damage
turbine and steam line
turbine only
boiler tubes
none of the above
Which of the following statements is true?
Shunt reactors are used to reduce the line impedance
Shunt reactors are used to eliminate line to ground capacitance
Shunt reactors are used for power factors improvement.
Shunt reactors are used to control the line voltage.
When a stator neutral of a generator is earthed through a distribution transformer, the stator earth fault is detected through
an over-current relay connected across the secondary of the transformer
an under-voltage relay connected across the secondary of the transformer
an over-voltage relay connected across the secondary of the transformer
none of the above
f high pressure heaters of steam cycle in power plant have high water level, what precaution shall be taken.
bypass the heater from water side and close extraction value
rip the boiler feed pump
trip the boiler
trip the turbine
Which one of the following statements is not true?
Corona loss and radio and TV interference with D.C. transmission is less
Fault levels in an all a. c system are less than in an a. c system with a D.C. link operating
Large systems may be interconnected with d. c link of small capacity
Limitation on the critical length of underground cables for use in A. C no longer exists if D.C transmission by cables is used.
Advantage of power system interconnection is
Optimization of machine can be done properly
Fewer machines are required as reserve for operation at peak loads
Large size circuit breakers are required because of large short-circuit currents
Machines of one system remain in step with machines of another system
. Economic studies have shown that D.C. transmission is cheaper than a. c transmission for lengths
beyond 1200 km
beyond 600 km
less than 100 mile
below 300 km
Governors for controlling the speed of power generation units provide
A flat speed -load characteristics
Speed is proportion with the load
An increase of speed with increasing load
A decrease of speed with increasing load
When two identical generating units are operated in parallel on governor control, and one machine has a 5% governor droop and the other a 10 % droop , the machine with the greater governor droop will
Share load equally with the other machine
Tend to take the larger portion of load changes
Tend to take the greater portion of load changes
Tend to take the lesser portion of load changes.
On load-frequency control installations, error signals are developed proportional to the frequency error. If frequency declines , the error signal will act to
Increase impedance of the line
Increase generator voltages
Increase prime move input to the generators
Reduce prime mover input to the generators
When inter-connected power systems operate with tie-line bias, they will respond to
Frequency changes only
Tie-line load changes only
Drooping voltage
Both frequency & tie -line load changes
When generating units in a power plant are loaded with equal incremental costs, the cost of generation is
maximum
minimum
zero
not affected
Incremental heat - rate curves for thermal generating units are used to determine the
Optimal cost
fuel cost in P/hour
none of the above
values to which the units should be loaded to decrease the fuel costs to a minimum
In economic operation of a power system , the effect of increased penalty factor between a generating plant and system load centre is
To maintain power factor of the plan
to decrease the load on the generating plant
to increase the load on the plant
to hold the plant load constant.
Non-conventional source-based power plants are generally best suited for
Island
Working with the nearby power grid
Operation with similar plants irrespective of length of connecting transmission system
Isolated operation from the power grid
Running cost of a hydro plant with respect to that of a thermal plant is
Less
Varying from installation to installation
equall
More
Pick up the odd plant from the following
Steam
Tidal
Hydro
Nuclear
Pick up the odd plant from the following:
Wind turbine generator plant
Tidal
Steam
Solar
The role of the economiser is to pre-heat
Air used for combustion
Boiler feed water
Pulverised coal
provide clean air
Superheater & reheater are used to
decrease efluent
heat air used for combustion
heat boiler feed water
improve the condition of steam
Governor is used with the steam turbine to regulate
Steam pressure
Steam temperature
Speed
Power output
Cooling of 500 MW turbo-generators is usually done by the following coolants
Water only
Nitrogen & hydrogen
Carbon dioxide & hydrogen
Hydrogen & water
The specific speed of a hydro turbine depends on
Actual speed
Output power
Actual speed ,head of operation & output power
Head of operation
The most common type of hydro turbine with a moderate value of the specific speed is
Pelton
Kaplan
wind
Francis
Pumped storage hydroelectric plant can be operated with
Upstream reservoir only
downstream reservoir only
with both as above
none of the above
Hydro-generators are usually
Bipolar machine
Salient pole machines
Homopolar machines
Round rotor machines
Heavy water in a nuclear reactor is used for
Moderation only
Cooling and shielding radiation
Moderation & shielding radiation
Cooling & moderation
The size and weight per unit power of a fast breeder reactor in comparison to a reactor of any of the thermal types is
more or less the same
Much less
Much more
always zero
Compared to turbines in the conventional coal-fired thermal stations, nuclear power plant turbines use steam at
lower pressure & temperature
higher pressure & temperature
higher power factor
higher temperature & lower pressure
Gas turbine temperature corresponds to
Around 66000 deg C
Around 1000 deg.C
Superheated steam temperature of 550 deg.C
Boiling water temperature of 100 deg.C
Gas turbine works on
Carnot cycle
Rankine cycle
Roel cycle
Brayton cycle
The HVDC converter
Consumes as much reactive power as real power
Consumes 50% of the real power
Does not consume reactive power
Is not economical
A back to back HVDC link can be advantageous compared to AC primarily because
It is costly
Of stability considerations
It is cheaper
Of controlled power glow
A 12-pulse bridge is preferred in HVDC because
It results in better power factor
cheaper
Series connection of converters on D.C. side is better
It eliminates certain harmonics
Fault on a two terminal DC link is removed by
Current chopping
Breakers on DC side
Current control of converters
Breakers on AC side
From the economic point of view , a power system should have a load factor
zero
About 0.12
About 1
About 0.5
From the economic point of view , a power system should have a diversity factor
Greater than one
Always constant
Much less than 1
Nearly equal to but less than one
Peak load hydro power plants compared to base load thermal plants have plant capacity factor
Almost equal
Much higher
Always constant
Much lower
Run-of-river plants are used for
Near base load
Base load operation
Regulating plan
Peak load operation
The two-part tariff is based on
MVArH
MW and MVar
MW and MVA
MWH and MVA
SF6 gas has excellent heat transfer properties because of its:
Low cost
High gaseous viscosity.
Higher molecular weight.
Low density
In order to have lower cost of electrical energy generation:
The load factor and diversity factor should be high
The load factor should be high but diversity factor low.
The load factor and diversity factor should be low.
The load factor should be low but diversity factor should be high.
For stability and economic reasons we operate the transmission line with power angle in the range:
60 deg to 75 deg.
10 deg. to 25 deg.
30 deg. to 45 deg.
65 deg. to 80 deg.
For an existing a. c. transmission line the string efficiency is 80%. Now if d.c. voltage is supplied for the same set up, the string efficiency will be:
Less than 80%.
100%.
80%.
More than 80%.
Effect of increase in temperature in overhead transmission lines is to:
Decrease the stress but increase the length.
Decrease the strength and length.
None of the above.
Increase the strength and length.
For economic operation, the generator with highest positive incremental transmission loss will operate at:
The lowest negative incremental cost of production.
The highest positive incremental cost of production.
None of these
The lowest positive incremental cost of production
An alternator is delivering the load current; its percent regulation is found to be zero. The type of load it delivers is:
Inductive
Resistive
Capacitive
admittance
The incremental transmission loss of a plant is:
zero
Negative always
Positive always.
Can be positive or negative.
Load flow study is carried out for:
System planning
Stability studies
Load frequency control
Fault calculations
If the penalty factor of a plant is unity, its incremental transmission loss is:
10.0
–1.0.
1.0.
Zero.
If the load of an isolated generator is increased without increasing the power input to the prime mover
The generator field current will increase.
The generator will slow down.
The generator will speed up.
The generator voltage will increase.
When alternative sources of energy are available to a power system, they should be Used in such a way that:
Overall production cost is minimized
The most efficient plants are always loaded to their maximum
Thermal generation is held at a minimum
Near at the load point
In a thermal-electric generating plant, overall efficiency is improved when
It is always loaded
Boiler pressure is increase
The difference between initial pressure and temperature and exhaust pressure and temperature are held at a maximum
Load on the units is increased
When load on a thermal unit is increased, fuel input
Decrease
Increase
Does not change
It is constant
Incremental-heat-rate curves, for thermal generating units, are used to determine the
Ramp rate
Fuel cost in P per hour
Values to which the units should be loaded to result in minimum fuel cost
Cost per unit of electrical output
When generating units are loaded to equal incremental cost:
Losses are minimized
Fuel cost is at a maximum
Fuel cost is not affected
Minimum fuel cost result
One advantage of computer control of generating units is that:
Incremental fuel costs
Loading of the units will be frequently adjusted to maintain them at equal
Var output of the unit is minimized
All units under the control of the computer will be loaded to the same load
If the fuel cost of one unit, operating in parallel with other units, is increased and it is desired to maintain fuel cost, the load on the unit will be
Decrease
Increase
Held constant
all of these
In a power system using both hydro and thermal generation, the proportion of hydro generation can be increased by
Increasing the field currents of the hydro generators
Used water with high specific gravity
Increasing the prize (gamma) of the water
Reducing the prize of the water
In economic operation of a power system, the effect of increased penalty factor between a generating plant and system load center is to
none of these
Increase load on the plant.
Decrease load on the generating plant.
Hold the plant load constant
Governors for controlling the speed of electric generating units normally provide
A decrease of speed with increasing load
An increase of speed with increasing load
A flat speed load characteristic
Governors for controlling the speed of electric generating units normally provide
A decrease of speed with increasing load
A flat speed load characteristic
An increase of speed with increasing load
On load –frequency-control installation, error signals are developed proportional to the frequency error. If frequency decline, the error signal will act to
Increase generator voltages
Reduce prime mover input to the generators
Increase prime mover input to the generators
When to or more system operate on an interconnected basis, each system
Should provide for its own reserve capacity requirement
Can depend on the other systems for its reserve requirements
Should operate in a “flat frequency” mode
When interconnected power system operate with tie-line bias, they will respond to
Frequency changes only
Tie-line load changes only
Both frequency and tie-line load changes
A metering installation for a 115-kV tie point between two power system has 10000:5 current transformers in each phase and 600:1 potential transformers connected line to ground. Assuming unity power factor, the multiplying factor that should be used to determine the power in the circuit in kilowatts is
207.8
3600
360
Inadvertent energy accumulation between power system are normally balanced by scheduling compensating deliveries of power
On week endsOn week ends
During periods corresponding to those in which the inadvertent energy was accumulated.
During off-pick periods
Wired supervisory control system are
More reliable than computer-based systems
Limited by cost and complexity when many devices are to be controlled.
Immune from induced electrical interference
Less expensive when many devices are to be controlled
SCADA systems require
A separate communication channel for each RTU
Continuous attendance at each remote station
A mean of entering and retrieving data at the master unit
Frequency-shift data channels to the RTU
One of the factor affecting power system reliability is
The nominal system transmission-voltage levels
The ratio of hydro to thermal generation
The available reserve capacity margin
Spinning reserve is generating capacity that
Is available by starting gas-turbine generating units
Has the lowest fuel cost
Is synchronous and online, with capacity in excess of existing loads
The spinning reserve to be carried on a system is
Determined by the amount of load on the system
A policy matter
Determined by the system operator (dispatcher)
The risk affecting spinning-reserve requirement of a system, in addition to the most heavily loaded units, include
The time of the daily peak load
The net amount of imported power
The net amount of exported power
Spinning reverse should
Be carried on the largest unit available
Be reduced during off-peak hours
Be divided among units at various locations on a system
In the event of a major loss of generation in an interconnected area, a system operator should
Open tie lines only as a last resort with power flowing out and declining frequency
Immediately open tie lines to other system
Open tie lines if power is flowing out of the system
House units are sometimes provided at thermal power plants to
Supply power to plant auxiliaries
Provide for station and yard light
Keep the station batteries charged
Of the Lightning arresters sold in the market, which can handle much large surge current and excessive contamination of dirtstation arrester
line arrester
Distribution arrester
station arrester
intermediate arrester
The Location of lightning arrester should be
away from the transformer
near from the disconnect
near the circuit breaker
near the transformer
The choice between ac and dc transmission is determined by
The operating voltage
The size of the conductors
Engineering and economic factors
The ratio of the average load on the plant for the period of time considered to the aggregate rating of all the generating equipments
Load factor
Capacity factor
Utilization factor
Diversity factor
The most economical size of a feeder is that size for which the annual cost of energy lost in the feeder equals the cost of interest and depreciation on the capital cost of the conductor material.
Faraday’s Law
Kirchoff’s Law
Kelvin’s Law
Law on Economics
Minimum oil circuit breaker is preferred in
High voltage
Medium voltage
low voltage
Extra High voltage
Breaking Capacity of circuit breakers is expressed in
kV
KAIC
MVA
AH
Type of water wheels used in hydraulic plants
reaction
all of these
impulse
propeller
Power plant curves or graphs showing the direct relationship of the peak load and the generated energy of the said plant
none of the above
modified load curve
load curve/graph
load duration curve
The advantage of using static capacitor to improve the power factor is because they
provide continuous charge of power factor
are not variable
are most loss free
none of these
Is an equipment which controls the gate or valve opening of the prime mover
silicon controlled rectifier
governor
rheostat
contactor
Is the mechanism which is used for moving a removable circuit breaker unit to end from the connected, disconnected and test positions
blocking device
position changing system
permissive control device
notching device
Is used to increase or decrease in one step, the value of feild excitation on a machine
field changing contactor
DC reclosing relay
filed regulator
tripping relay
In a generating and distribution system, current balance is provided by protective zones which are
used to trip all circuit breaker in the system
monitored by differential relays
used to eliminate reflections on short transmission lines
isolated during fault by disconnect switches
In switchgear application, the term “dead fronts” means that
the front and rear panels are hinged
no equipment is mounted on the front pane
an access door is at the end of the structure
energized parts are not exposed on the front panel
Which of the following steps is used for isolating a circuit breaker in power stations for maintenance purposes?
open the disconnect switches
turn off the main generator
ground the auxiliary contacts
pull the substation fuses
The ratio of the average load on the plant for the period of time to the aggregate rating of all generating equipment
capacity factor
maintenance factor
Plant use factor
power factor
The ratio of the individual maximum demands of the systems to the overall maximum demand of the whole system
utilization factor
diversity factor
load factor
demand factor
In parallel operation of alternator, if the excitation of one alternate is changed it will only change
synchronizing power of the machine
reactive power taken by the machine
apparent power taken by the machine
real power taken by the machine
The maximum past or present demand, which are taken into account to establishing billings for the previous or subsequent periods
diversity demand
Seasonal Diversity
Ratchet Demand
meter demand
The ratio of the maximum coincident total demand of a group of consumers to the sum of the maximum power demand of the individual consumers comprising the group both taken at the same point of supply for the same time.
Plant use (Output) factor
Non- Coincidence factor
Utilization Factor
Coincidence factor
The ratio of the average load for a given period to the operating capacity in actual service only (for multi-set plant).
Load factor
Demand factor
Capacity factor
Diversity factor
The product of the load factor (LF) and the demand factor (DF)
Use Factor
Plant factor
Average factor
Connected Load factor
The water enters the spiral case from the penstock, passes through the stay ring guided by the stationary stay ring vanes, then through the movable wicket gates through the runner and into the draft tube through which it flows into a tailrace or tailwater reservoir. This type of hydraulic turbine is known as
Axial flow turbine
Impulse Turbine
Propeller type
Francis type
It pertains to the units available, maintained at operating temperature and ready for service although not in actual operation.
cold reserve
Hot reserve
spinning reserve
Operating reserve
It is the product of the Utilization factor (UF) and Load factor (LF).
Connected Load factor
Capacity factor
Use Factor
Average factor
To produce one kW-hr a power plant burns 0.9 lb of coal with a heating value of 13,000 BTU per lb. What is the heat rate of the plant?
11,700 BTU/kW-hr
8,700 BTU/kW-hr
6,250 BTU/kW-hr
9,500 BTU/kW-h
A 100 MW power plant has a heat rate of 2.88 x 10 6 calories per kW-hr. It is a base load plant and runs at full load 24 hrs a day. How many tons of coal is needed per day?
830
960
625
250
The feedwater is usually heated before it is injected to the boiler for the following reason EXCEPT one. Which one is this?
Derating types of preheaters permit the removal of dissolves gases from the feedwater
Recover part of the flue gas heat which is otherwise lost to the atmosphere
Increase the efficiency of the boiler
Improves the overall performance of the plant
An effective remover of dust, carbon particles and others from the flue gas of the power plant is called _____.
Dust scrubber
Soot blower and collector
Mechanical collector
Electrostatic Precipitator
It is the modern equipment of removing sulfur content from the flue gas of the power plant.
ESP
EMS
DAC
FGD
In fission, energy is produced when.
Molecules combine
Nuclear particles combine
Chemical compound splits into its constituents
Nuclear particles split
In the list below which one is not a type of present day nuclear power plant.
fast breeder reactor
boiling water
low pressure reactor
fusion-fission reactor
How does the output of the hydraulic turbine vary with the diameter of the blade?
It varies directly as the cube of the diameter of the blade
It varies directly as the two-thirds power of the diameter of the blade
It varies directly as the diameter of the blade
It varies directly as the square of the diameter of the blade
A ten-year investigation of rivers potential gave an average water flow of 25 cm per second at the bottom and 90 cm per second at the surface. The average cross section at the same location is 80 sq. m. What is the average flow rate in cubic meter per hour?
5,760
57,500
46,500
165,000
A power plant gets water from a dam from a height of 122.45 meters at the rate of 1,000 cubic meters per minute. If the output of the plant is 15,000 kW, what is the efficiency?
80%
75%
65%
70%
An industry having a maximum demand of 1000 kW works for 320 days in a year, 8 hrs per day. Assuming that it works at full capacity all the time during working days, calculate the daily load factor.
29.5 %
33.3 %
67 %
56.2 %
A 100 MW power station delivers 100 MW for 2 hrs, 50 MW for 6 hrs and is shut down for the rest of each day. It is also shut down for maintenance for 45 days each year. Calculate the annual load factor.
78.5%
20.83%
56.9 %
20.1 %
A power station has a load cycle as follows: 260 MW for 6 hrs 200 MW for 8 hrs 160 MW for 4 hrs 100 MW for 6 hrs If the power station is equipped with 4 sets of 75 MW each, calculate the capacity factor
76.5 %
34.5 %
61.1 %
23.6 %
The current loads of four circuits are as follows
Circuit no 1 = 25 Amperes
Circuit no 2 = 38 Amperes
Circuit no 3 = 18 Amperes
Circuit no 4 = 45 Amperes
If the diversity factor is 1.5. What is the minimum ampacity of the feeder conductor?
126 Amperes
84 Amperes
152 Amperes
189 Amperes
The metering of a power customer was read and gave the following data:
KW-hr = 200,000, KVAR- hr.= 180,000, Maximum demand = 380 kW, Billing days = 3
What is the load factor?
73%
62%
80%
68%
The power customer has four circuits of 220-volt three phase. The circuits have the maximum demand as follows:
Circuit no 1 = 35 Amperes
Circuit no 2 = 46 Amperes
Circuit no 3 = 72 Amperes
Circuit no 4 = 57 Amperes
The diversity factor is 1.5, the load factor is 50% and the power factor is 80%. What is the approximate kW demand of the customer?
53 kW
43 kW
21 kW
15 kW
The power customer has four circuits of 220-volt three phase. The circuits have the maximum demand as follows:
Circuit no 1 = 35 Amperes , Circuit no 2 = 46 Amperes, Circuit no 3 = 72 Amperes, Circuit no 4 = 57 Amperes
The diversity factor is 1.5, the load factor is 50% and the power factor is 80%. Determine the maximum KVA demand of the customer?
26.5
80
53
46
A Diesel station supplies the following loads to various consumers:
Industrial consumer = 1500 kw
Commercial estabkishment = 750 kw
Domestic power = 100 kw
Domestic light = 450 kw
If the maximum demand on the station is 2500 kw and the number of kwh generated per year is 45 x 10 5 , determine the diversity factor and load factor.
21.1, 50.2%
1.53, 65.7%
97, 31.2%
1.12, 20.5%
A 100 MW coal fired power plant has an average heat rate of 9,500 BTU/ kWh. The plant load factor is 75%; the heating value of coal is 12,000 BTU/ lb. Calculate the amount of coal usage for one day
1.425 x 10 6 lbs.
2.235 x 10 5 lbs
1.425 x 10 6 lbs.
1.826 x 10 6
A Power Plant has a maximum demand of 15 MW. The annual load factor and capacity factor are 50 % and 40%, respectively. Determine the reserve capacity of the plant.
3750 kW
5370 kW
7350 kW
3075 kW
A diversity factor of 2.5 gives a saving of ___________ % in the generating equipment.
25
40
60
50
A coal Thermal Power Plant has a boiler, turbine and alternator efficiencies of 35%, 86%, and 93% respectively. Coal with heating value of 12,000 BTU per lb cost P 1.5 per lb. What is the fuel cost in producing 1 kW?
P 1.62 per kW
P 1.52 per kW
P 1.75 per kW
P 1.9 per kW
A certain coal fired power plant has a heat rate of 2.88 x 10 8 calories per kW-hr. Coal costs P 2,500 per Ton. How much is the fuel cost component of producing 1 kW-hr?
P 1.25
P 1.75
P 2.50
P 1.00
A power station has a load cycle as under
260 MW for 6 hrs 200 MW for 8 hrs 160 MW for 4 hrs 100 MW for 6 hrs
If the power station is equipped with 4 sets of 75 MW each, calculate the daily fuel requirement if the calorific value of the oil used were 10,000 Kcal/kg and the average heat rate of the station were 2,860 Kcal/kW.
1890 tons
3452 tons
1258.4 tons
7641 tons
A diesel generator set burns diesel with a heating value of 18,000 BTU per lb. The diesel engine has an efficiency of 30% and the alternator has an efficiency of 95%. Determine the fuel cost component of producing one kW-hr if diesel cost P 2.8 per lb.
P 0.15
P 1.86
P 2.15
P 3.28
A proposed hydroelectric station has an available head of 30 m, a catchment area of 50 x 10 6 sq. m, the rainfall for which is 120 cm per annum. If 70% of the total rainfall can be collected, calculate the power that could be generated. Assume the following efficiencies: Penstock 95%, Turbine 80%, and Generator 85%.
925 kW
214 kW
678 kW
253 kW
The load of an instrument transformer consisting of delicate moving elements of an ammeter, voltmeter and wattmeter is termed as
Transformer power
Instrument Impedance
meter load
burden
At a 155 kV substation the PT ratio is 1000:1 and the CT ratio is 1200:5. The potential going into the wattmeter is 155 V. What is the MW indicated when the wattmeter reads 800 watts
150 MW
192 MW
19.2 MW
15.0 MW
When alternative sources of energy are available to power system, they should be used in such a way that
The most efficient plants are always loaded to their maximum
Overall production cost is minimized
Thermal generation is held at minimum
Used Diesel Power plant
n thermal electric generating plant, overall efficiency is improved when
Increased the no. of generator
Boiler pressure is increased
The difference between initial pressure and temperature and exhaust pressure and temperature are held at a maximum
Load on the units is increased
One advantage of computer control of generating units is that
All units under the control of the computer will be loaded to the same load
It can control all equipment
Var. output of the units are minimized
Loading of the units will be frequently adjusted to maintain them at equal incremental cost
The most economical cross section of a conductor is that which makes the interest on the capital outlay plus depreciation due to the conductor in the cable equal to the annual cost of energy loss.
Ferranti law
Vanderwhaals Law
Mc Kevins Law
Kelvins law
Inadverent accumulations between power systems are normally balanced by scheduling compensating deliveries of power
During periods corresponding to those in which the inadverent energy was accumulated
On base load plant
On weekends
During off-peak load
Spinning reserve is generating capacity that
A policy matter
Has the lowest fuel cost
Is available by starting Gas- Turbine generating units
Is synchronized and online, with capacity in excess of existing load
Ferroresonance is a condition that may occur on
Transformer
Distribution line
Capacitor
Transmission line
Subsynchronous resonance is a condition that may occu on
Loss of load on transmission line
Short transmission line
Increase of load on line
Long, heavily loaded line
Heating value of coal largely depend on
moisture content
volatile matter
size of coal particle
ash content
Power plant using coal work closely on which of the following cycle
Brayton cycle
Otto cycle
Rankine cycle
Binary vapour cycle
Which of the following contributes to the efficiency of Rankine cycle in thermal power plant.
Reheating of steam at intermediate stag
Regeneration use of steam for heating boiler
Used of high pressure
All of these
In steam turbine cycle, the lowest pressure occurs in
Boiler
Superheater
Condenser
Turbine inlet
For low head and high discharge the hydraulic turbine used is.
Jonvas
Pelton wheel
Francis type
Kaplan
Overall efficiency of Gas Turbine is
equal to Rankine cycle efficiency
equal to Carnot cycle efficiency
More than Otto or Diesel cycle efficiency
Less than Diesel cycle efficiency
The function of moderator in Nuclear Reaction is
to control the reaction
to liberate excessive neutron
to absorb excessive neutrons
to accelerate the reaction
During load shedding
some loads are switch off
some loads are switch off
system frequency is reduced
system voltage is reduced
A low utilization factor for a plant indicates that
plant is used for peak load
plant is used for standby purpose only
plant is under maintenance
plant is used for base load only
Which of the following relations is incorrect?
Demand factor x Connected load = Maximum demand
Load factor x Maximum load = Average load
Capacity factor = Utilization factor x Load factor
None of the above
When paralleling a generating unit to a power system, if the synchroscope indicates that the incoming machine is running slower than the system:
The synchronizing switch should be closed just after it indicates zero phase angle difference.
The power input to the prime mover should be decreased slightly
The field current should be increased
The power input to the prime mover should be increased slightly
When load on a thermal unit is increased, fuel input
slightly decreased
Does not change
Decreased
Increased
When generating units are loaded to equal incremental cost:
Fuel cost are not affected
Minimum fuel cost result
Fuel cost at a maximum
efficiency decreased
In a power system using both Hydro and thermal generation, the proportion of hydro generation can be increased by.
Used salt water
Increasing the price of water
Reducing the price of water
Increasing the field current of the Hydro generators
Which of the following methods of generating electric power from the sea is more advantageous?
Tidal power
Ocean power
Water power
sea power
The efficiency of a thermal power plant improves with.
Use of high steam pressure
Lower load on the plant
increased quantity of coal burnt
Larger quantity of water used
A Gas turbine works on
Rankine cycle
Dual cycle
Carnot cycle
Brayton cycle
Air standard efficiency of a diesesl engine depends on
torque
speed
fuel
compression ratio
Most of the heat generated in internal combustion engine is lost in
radiation
lubricating oil
cooling water
exhaust gases
Capital cost per MWh is highest in case of
Hydroelectric
Nuclear power plant
Diesel engine
steam power plant
A diesel power plant is best suited as
general purpose plant
stand by power plant
base load plant
peak load plant
A Nuclear Power plant is invariably used as a
spinning reserve plant
stand by plant
peak load plant
base load plant
Economizers are used to heat
steam
feedwater
boiler
air
Surge tank is provided for the protection of
blade
weir
penstock
intake pipe
A generating station has a connected load of 43 MW an a maximum demand of 20 MW, the units genetrated being 61.5 x 10 6 per annum. Calculate. The load factor
351. %
17.9%
76%
64.8%
For the same maximum demand, if the load factor is decreased the cost of energy is
no relation
not affected
decreased
increased
