Generation & Transmission

Consider a distribution feeder, with $R / X$ ratio of 5 . At the receiving end, a 350 kVA load is connected. The maximum voltage drop will occur from the sending end to the receiving end, when the power factor of the loa...

Two units, rated at 100 MW and 150 MW , are enabled for economic load dispatch. When the overall incremental cost is $10,000 \mathrm{Rs}$./MWh, the units are dispatched to 50 MW and 80 MW respectively. At an overall incr...

A 50 Hz, 275 kV line of length 400 km has the following parameters: Resistance, R = 0.035 $$\Omega$$/km; Inductance, L = 1 mH/km; Capacitance, C = 0.01 $$\mu$$F/km; The line is represented by the nominal-$$\pi$$ model. W...

The expressions of fuel cost of two thermal generating units as a function of the respective power generation $${P_{G1}}$$ and $${P_{G2}}$$ are given as $$\matrix{ {{F_1}({P_{G1}}) = 0.1aP_{G1}^2 + 40{P_{G1}} + 120\,Rs/h...

If only 5% of the supplied power to a cable reaches the output terminal, the power loss in the cable, in decibels, is ______. (round off to nearest integer).

The fuel cost functions in rupees/hour for two 600 MW thermal power plants are given by Plant 1 : C 1 = 350 + 6P 1 + 0.004P$$_1^2$$ Plant 2 : C 2 = 450 + aP 2 + 0.003P$$_2^2$$ where P 1 and P 2 are power generated by pla...

Two generators have cost functions $F_1$ and $F_2$. Their incremental-cost characteristics are $$ \frac{d F_1}{d P_1}=40+0.2 P_1 \text { and } \frac{d F_2}{d P_2}=32+0.4 P_2 $$ They need to deliver a combined load of 260...

Two single-core power cables have total conductor resistances of $0.7 \Omega$ and $0.5 \Omega$ respectively and their insulation resistances (between core and sheath) are $600 \mathrm{M} \Omega$ and $900 \mathrm{M} \Omeg...

A 3-phase 50 Hz generator supplies power of 3 MW at 17.32 kV to a balanced 3-phase inductive load through an overhead line. The per phase line resistance and reactance are 0.25 $$\Omega $$ and 3.925 $$\Omega $$ respectiv...

A single-phase transmission line has two conductors each of 10 mm radius. These are fixed at a center-to-center distance of 1 m in a horizontal plane. This is now converted to a three-phase transmission line by introduci...

Consider the economic dispatch problem for a power plant having two generating units. The fuel costs in $$Rs/MWh$$ along with the generation limits for the two units are given below: $$\eqalign{ & {C_1}\left( {{P_1}} \ri...

The incremental costs (in rupees/$$MWh$$) of operating two generating units are functions of their respective powers $${P_1}$$ and $${P_2}$$ in $$MW,$$ and are given by $$${{d{C_1}} \over {d{P_1}}} = 0.2{P_1} + 50$$$ $$$...

For a $$400$$ $$km$$ long transmission line, the series impedance is $$(0.0 + j0.5)$$ $$\Omega /km$$ and the shunt admittance is $$(0.0 + j5.0)$$ $$\mu \,mho/km.$$ The magnitude of the series impedance (in $$\Omega $$) o...

Shunt reactors are sometimes used in high voltage transmission systems to

The undesirable property of an electrical insulating material is

A three phase star-connected load is drawing power at a voltage of 0.9 pu and 0.8 power factor lagging. The three phase base power and base current are 100 MVA and 437.38 A respectively. The line-to-line load voltage in...

The fuel cost functions of two power plants are Plant $${P_1}:\,{C_1} = 0.05\,Pg_1^2 + AP{g_1} + B$$ Plant $${P_2}:\,{C_2} = 0.10\,Pg_2^2 + 3AP{g_2} + 2B$$ Where, $$P{g_1}$$ and $$P{g_2}$$ are the generator powers of two...

The horizontally placed conductors of a single phase line operating at $$50$$ $$Hz$$ are having outside diameter of $$1.6$$ cm, and the spacing between centers of the conductors is $$6$$ m. The permittivity of free space...

In a long transmission line with $$r, l, g$$ and $$𝑐$$ are the resistance, inductance, shunt conductance and capacitance per unit length respectively, the condition for distortionless transmission is

A nuclear power station of $$500$$ $$MW$$ capacity is located at $$300$$ km away from a load center. Select the most suitable power evacuation transmission configuration among the following options.

For enhancing the power transmission in along $$EHV$$ transmission line, the most preferred is to connect a

For a fixed value of complex power flow in a transmission line having a sending end voltage $$V$$, the real power loss will be proportional to

Match the items List-$${\rm I}$$ (To) with the items in List-$${\rm II}$$ (Use) and select the correct answer using the codes given below the lists. List-$${\rm I}$$ $$A.$$ improve power factor $$B.$$ reduce the current...

An extra high voltage transmission line of length $$300$$ km can be approximate by a lossless line having propagation constant $$\beta = 0.00127$$ radians per km. then the percentage ratio of line length to wavelength wi...

A lossless transmission line having Surge Impedance Loading $$(SIL)$$ of $$2280$$ $$MW.$$ A Series capacitive compensation of $$30$$% is emplaced. Then $$SIL$$ of the compensated transmission line will be

A lossless power system has to serve a load of $$250$$ $$MW.$$ There are two generators ($$G1$$ and $$G2$$) in the system with cost curves $${C_1}$$ and $${C_2}$$ respectively defined as follows: $${C_1}\left( {{P_{G1}}}...

The total reactance and total susceptance of a lossless overhead $$EHV$$ line, operating at $$50$$ $$Hz,$$ are given by $$0.045$$ pu and $$1.2$$ pu respectively. If the velocity of wave propagation is $$3\,\, \times \,\,...

The concept of an electricity short, medium and long line is primarily based on the

A generator is connected through a $$20$$ MVA, $$13.8/138$$ kV step up transformer, to a transmission line. At the receiving end of the line a load is supplied through a step down transformer of $$10$$ MVA, $$138/69$$ kV...

The concept of an electrically short, medium, and long line is primarily based on the

The $$A, B, C, D$$ constant of a $$220$$ $$kV$$ line are: $$A = D = 0.94\,\angle \,10,\,\,\,B = 130\,\angle \,730,\,\,\,C = 0.001\,\angle \,900.\,\,$$ If the sending end voltage of the line for a given load delivered at...

The insulation strength of an EHV transmission line is mainly governed by

A $$800$$ $$kV$$ transmission line is having per phase line inductance of $$1.1$$ $$mH/km$$ and per phase line capacitance of $$11.68$$ $$nF/km.$$ Ignoring the length of the line, its ideal power transfer capability in $...

The generalized circuit constants of a $$3$$-phase, $$220$$ $$kV$$ rated voltage, medium length transmission line are $$A = D = 0.936 + j\,0.016 = 0.936\angle {0.98^ \circ }$$ $$B = 33.5 + j138 = 142.0\angle {76.4^ \circ...

A lightning stroke discharges impulse current of $$10$$ kA (peak) on a $$400$$ kV transmission line having surge impedance of $$250\,\Omega $$. The magnitude of transient over-voltage traveling waves in either direction...

A $$110$$ $$kV,$$ single core coaxial, XLPE insulated power cable delivering power at $$50$$ $$Hz,$$ has a capacitance of $$125$$ $$nF/km.$$ If the dielectric loss tangent of XLPE is $$\,2\,\, \times \,\,{10^{ - 4}},$$ t...

In thermal power plants, the pressure in the working fluid cycle is developed by

For harnessing low variable water heads, the suitable hydraulic turbine with high percentage of reaction and runner adjustable vanes is

Incremental fuel costs (in some appropriate unit) for a power plant consisting of three generating units are $${\rm I}{C_1} = 20 + 0.3\,\,{P_1},\,{\rm I}{C_2} = 30 + 0.4\,\,{P_2},\,{\rm I}{C_3} = 30$$ Assume that all the...

A $$3$$-phase, $$11$$-$$kV$$ generator feeds power to a constant power unity power factor load of $$100$$ $$MW$$ through a $$3$$-phase transmission line. The line-to-line voltage at the terminals of the machine is mainta...

The ABCD parameters of a $$3$$-phase overhead transmission line are $$\,A = D = 0.9\angle {0^ \circ }.\,\,B = 200\,\angle {90^ \circ }\,\,\Omega \,\,\,$$ and $$\,\,C = 0.95\, \times \,\,{10^{ - 3}}\angle {90^ \circ }\,\,...

Bundled conductors are mainly used in high voltage overhead transmission lines to

A surge of 20 kV magnitude travels along a lossless cable towards its junction with two identical lossless overhead transmission lines. The inductance and the capacitance of the cable are 0.4 mH and 0.5 $$\mu F$$ per km....

Consider a long, two-wire line composed of solid round conductors. The radius of both conductors is $$0.25$$ cm and the distance between their centers is $$1$$m. If this distance is doubled, then the inductance per unit...

A long wire composed of a smooth round conductor runs above and parallel to the ground (assumed to be a large conducting plane). A high voltage exists between the conductor and the ground. The maximum electric stress occ...

A $$75$$ MVA, $$10$$ kV synchronous generator has X d $$= 0.4$$ p.u. The X d value (in p.u.) is a base of $$100$$ MVA, $$11$$ kV is

A power system has two generators with the following cost curves Generator $$1:$$ $${C_1}\left( {{P_{G1}}} \right) = 0.006\,P_{G1}^2 + 8{P_{G1}} + 350$$ (Thousand Rupees/Hour) Generator $$2:$$ $${C_2}\left( {{P_{G2}}} \r...

A 132 kV transmission line AB is connected to a cable BC. The characteristic impedances of the overhead line and the cable are 400$$\Omega $$ and 80$$\Omega $$ respectively. Assume that these are purely resistive. A 250...

The conductors of a $$10$$ km long, single phase, two wire line are separated by a distance of $$1.5$$ m. The diameter of each conductor is $$1$$ cm. If the conductors are of copper, the inductance of the circuit is

A lossless radial transmission line with surge impedance loading

In a thermal power plant, the feed water coming to the economiser is heated using

The incremental cost characteristic of two generators delivering $$200$$ $$MW$$ are as follows $$\,\,\,{{d{F_1}} \over {d{P_1}}} = 20 + 0.1{P_1},\,\,{{d{F_2}} \over {d{P_2}}} = 16 + 0.2{P_2}$$ For economic operation, the...

A $$275$$ $$kV,$$ $$3$$-phase, $$50$$ $$Hz,$$ $$400$$ $$km$$ lossless line has following parameters: $$x=0.05$$ $$ohms/km,$$ line charging susceptance $$y=3.0$$ micro-Siemens/k. (a) Calculate the receiving end voltage on...

The corona loss on a particular system at 50 Hz is 1 kW/km per phase. The corona loss at 60 Hz would be

A 6.6 kV, 50 Hz single core lead sheathed cable has the following data: Conductor diameter: 1.5 cm, length: 4 km. Internal diameter of the sheath : 3 cm Resistivity of insulation : 1.3 $$ \times $$ 1012 $$\Omega $$-m. Re...

Corona losses are minimized when

$$A$$ $$220$$ kV, $$20$$ km long, $$3$$-phase transmission line has the following $$A, B, C, D$$ constants. $$A=D=0.96$$$$\angle {3^0},$$ $$\,B = 55\angle {65^0}\,\,\Omega /$$ phase, $$\,C = 0.5 \times {10^{ - 4}}\angle...

A 66 kV, 3-phase, 50 Hz, 150 km long overhead transmission line is open circuited at the receiving end. Each conductor has a resistance of 0.25$$\Omega $$/km, an inductive reactance of 0.5$$\Omega $$/km and a capacitive...

For a single phase overhead line having solid copper conductors of diameter $$1$$ cm, spaced $$60$$ cm between centers, the inductance in $$mH/km$$ is

An overhead line having a surge impedance of $$400$$$$\Omega $$ is connected in series with an underground cable having a surge impedance of $$100$$$$\Omega $$. If a surge of $$50$$ $$kV$$ travels from the line end towar...

Each conductor of a $$33$$ $$kV,$$ $$3$$ phase system is suspended by a string of three similar insulators. The ratio of shunt capacitance to mutual capacitance is $$0.1.$$ Calculate the voltage across each insulator, an...

A shunt reactor of $$100$$ MVAR is operated at $$98$$% of its rated voltage and $$96$$% of its rated frequency. The reactive power absorbed by the reactor is;

In a power system, the fuel inputs per hour of plants $$1$$ and $$2$$ are given as $${F_1} = 0.20\,P_1^2 + 30\,{P_1} + 100\,\,$$ Rs per hour $${F_2} = 0.25\,P_2^2 + 40\,{P_2} + 150\,\,$$ The limits of generators are $$$\...

A cable has the following characteristics. $$L = 0.201\,\,\mu H/m\,\,$$ and $$\,C = 196.2\,pF/m.\,$$ The velocity of wave propagation through the cable is

For a $$500$$ Hz frequency excitation, a $$50$$ km short power line will be modeled as

Which material is used in controlling chain reaction in a nuclear reactor?

For equilateral spacing of conductors of an untransposed $$3$$-phase line, we have

The insulation resistance of a cable of length $$10$$ km is $$1$$ $$M\Omega $$. For a length of $$100$$ km of the same cable, the insulation resistance will be

The surge impedance of a $$400$$ km long overhead transmission line is $$400$$ $$\Omega $$. For a $$200$$ km length of the same line, the surge impedance will be

The rated load of an underground cable is always _______its natural load.

The insulation level of a $$400$$ kV, EHV overhead transmission line is decided on the basis of

The charging current of a $$400$$ kV transmission line is more than that of a $$220$$ kV line of the same length.

The increase in resistance due to non-uniform distribution of current in a conducto $$r$$ is known as _______effect

In a $$400$$ kV network, $$360$$ kV is recorded at a $$400$$ kV bus. The reactive power absorbed by a shunt reactor rated for $$50$$ MVAR, $$400$$ kV connected at the bus is

Consider a three-phase, $$50$$ $$Hz$$, $$11$$ $$kV$$ distribution system. Each of the conductors is suspended by an insulator string having two identical porcelain insulators. The self capacitance of the insulator is $$5...

A three phase overhead transmission line has its conductors horizontally spaced with spacing between adjacent conductors equal to 'd'. If now the conductors of the line are rearranged to form an equilateral triangle of s...

The inductance of a power transmission line increases with