MCQOPTIONS
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MCQOPTIONS
This section includes 146 Mcqs, each offering curated multiple-choice questions to sharpen your Power Systems knowledge and support exam preparation. Choose a topic below to get started.
| 101. |
The maximum discharge of steam through a convergent-divergent nozzle depends upon |
| A. | area of nozzle at throat |
| B. | initial pressure and volume of steam |
| C. | final pressure ofsteam leaving the nozzle |
| D. | both (a) and (b) |
| Answer» E. | |
| 102. |
The ratio of the energy supplied to the blades per kg of steam to the total energy supplied per stage per kg of steam is called mechanical efficiency. |
| A. | Yes |
| B. | No |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 103. |
The purpose of governing in steam turbines is to |
| A. | maintain the speed of the turbine |
| B. | reduce the effective heat drop |
| C. | reheat the steam and improve its quality |
| D. | completely balance against end thrust |
| Answer» B. reduce the effective heat drop | |
| 104. |
In a velocity compounded impulse turbine, when steam flows through the second row of moving blades, |
| A. | velocity increases |
| B. | velocity decreases |
| C. | velocity remains constant |
| D. | pressure remains constant |
| Answer» C. velocity remains constant | |
| 105. |
In turbines, the fluid undergoes a continuous steady flow process and the speed of flow is |
| A. | low |
| B. | very low |
| C. | high |
| D. | very high |
| Answer» E. | |
| 106. |
The critical pressure ratio for initially wet steam is |
| A. | 0.546 |
| B. | 0.577 |
| C. | 0.582 |
| D. | 0.601 |
| Answer» D. 0.601 | |
| 107. |
Multi-stage steam turbines are of the |
| A. | velocity compounded type |
| B. | reaction type |
| C. | pressure compounded type |
| D. | all of these |
| Answer» E. | |
| 108. |
The efficiency of an impulse turbine is maximum when (where Vb = Blade speed, V = Absolute velocity of steam entering the blade, and α = Nozzle angle) |
| A. | Vb = 0.5 V cos α |
| B. | Vb = V cos α |
| C. | Vb = 0.5 V2 cos α |
| D. | Vb = V2 cosα |
| Answer» B. Vb = V cos α | |
| 109. |
In a reaction turbine, when steam flows through the moving blades, |
| A. | pressure increases while velocity decreases |
| B. | pressure decreases while velocity increases |
| C. | pressure and velocity both decreases |
| D. | pressure and velocity both increases |
| Answer» D. pressure and velocity both increases | |
| 110. |
The turbine blades are |
| A. | straight |
| B. | circular |
| C. | curved |
| D. | None of these |
| Answer» D. None of these | |
| 111. |
Parson's reaction turbine is a __________ reaction turbine. |
| A. | 40 percent |
| B. | 50 percent |
| C. | 60 percent |
| D. | 70 percent |
| Answer» C. 60 percent | |
| 112. |
In a convergent divergent nozzle, the discharge depends upon the initial conditions of steam and the area of nozzle at throat. |
| A. | Correct |
| B. | Incorrect |
| C. | Can't say |
| D. | None of these |
| Answer» B. Incorrect | |
| 113. |
The critical pressure ratio for initially dry saturated steam is more as compared to initially wet steam. |
| A. | Yes |
| B. | No |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 114. |
The stage efficiency (ηS) is given by (where ηB = Blading efficiency, and ηN = Nozzle efficiency) |
| A. | ηS = ηB x ηN |
| B. | ηS = ηB/ηN |
| C. | ηS = ηN/ηB |
| D. | none of these |
| Answer» B. ηS = ηB/ηN | |
| 115. |
In a nozzle, the effect of supersaturation is to |
| A. | decrease dryness fraction of steam |
| B. | decrease specific volume of steam |
| C. | increase the entropy |
| D. | increase the heat drop |
| Answer» D. increase the heat drop | |
| 116. |
The Rankine efficiency depends upon total useful heat drop and total isentropic heat drop. |
| A. | Correct |
| B. | Incorrect |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 117. |
Degree of reaction is defined as the ratio of |
| A. | heat drop in fixed blades to the heat drop in moving blades |
| B. | heat drop in moving blades to the heat drop in fixed blades |
| C. | heat drop in moving blades to the heat drop in fixed blades plus heat drop in moving blades |
| D. | heat drop in fixed blades plus heat drop in moving blades to the heat drop in moving blades |
| Answer» D. heat drop in fixed blades plus heat drop in moving blades to the heat drop in moving blades | |
| 118. |
When the cross-section of a nozzle increases continuously from entrance to exit, it is called a |
| A. | divergent nozzle |
| B. | convergent nozzle |
| C. | convergent-divergent nozzle |
| D. | none of these |
| Answer» B. convergent nozzle | |
| 119. |
The variation of steam pressure in the nozzle depends upon |
| A. | velocity of steam |
| B. | specific volume of steam |
| C. | dryness fraction of steam |
| D. | all of these |
| Answer» E. | |
| 120. |
The ratio of the workdone on the blades to the energy supplied to the blades, is called |
| A. | blading efficiency |
| B. | nozzle efficiency |
| C. | gross or stage efficiency |
| D. | mechanical efficiency |
| Answer» B. nozzle efficiency | |
| 121. |
A steam turbine, in which a part of the steam after partial expansion, is used for process heating and the remaining steam is further expanded for power generation, is known as |
| A. | back pressure turbine |
| B. | pass out turbine |
| C. | low pressure turbine |
| D. | impulse turbine |
| Answer» C. low pressure turbine | |
| 122. |
In a 50% reaction turbine stage, tangential component of absolute velocity at rotor inlet is 537 m/s and the blade velocity is 454 m/s. The power output in kW of steam will be |
| A. | 260 kW |
| B. | 282 kW |
| C. | 296 kW |
| D. | 302 kW |
| Answer» C. 296 kW | |
| 123. |
The pressure of steam at throat of a steam nozzle is called critical pressure. |
| A. | Agree |
| B. | Disagree |
| C. | Can't say |
| D. | None of these |
| Answer» B. Disagree | |
| 124. |
When the back pressure of a nozzle is below the designed value of pressure at exit of nozzle, the nozzle is said to be |
| A. | choked |
| B. | underdamping |
| C. | overdamping |
| D. | none of these |
| Answer» C. overdamping | |
| 125. |
The ratio of the useful heat drop to the isentropic heat drop is called |
| A. | condenser efficiency |
| B. | nozzle efficiency |
| C. | boiler efficiency |
| D. | vacuum efficiency |
| Answer» C. boiler efficiency | |
| 126. |
Steam turbines may be classified according to |
| A. | direction of steam flow |
| B. | number of stages |
| C. | mode of steam action |
| D. | all of these |
| Answer» E. | |
| 127. |
The maximum efficiency of a reaction turbine is |
| A. | 2 sin²α/(1 + sin²α) |
| B. | 2 cos²α/(1 + cos²α) |
| C. | (1 + sin²α)/2 sin²α |
| D. | (1 + cos²α)/2 cos²α |
| Answer» C. (1 + sin²α)/2 sin²α | |
| 128. |
The reheat factor depends upon |
| A. | initial pressure and superheat |
| B. | exit pressure |
| C. | turbine stage efficiency |
| D. | all of these |
| Answer» E. | |
| 129. |
A turbine is said to have an axial discharge when the steam leaves the blade tip at __________ to the direction of the blade motion. |
| A. | 60° |
| B. | 90° |
| C. | 180° |
| D. | 270° |
| Answer» C. 180° | |
| 130. |
A single stage impulse turbine with a diameter of 1.2 m runs at 3000 r.p.m. If the blade speed ratio is 0.42, then the inlet velocity of steam will be |
| A. | 79 m/s |
| B. | 188 m/s |
| C. | 450 m/s |
| D. | 900 m/s |
| Answer» D. 900 m/s | |
| 131. |
The difference of supersaturated temperature and saturation temperature at that pressure is called |
| A. | degree of supersaturation |
| B. | degree of superheat |
| C. | degree of undercooling |
| D. | none of these |
| Answer» D. none of these | |
| 132. |
In a nozzle, the effect of supersaturation is to increase the dryness fraction of steam. |
| A. | Yes |
| B. | No |
| C. | Can't say |
| D. | None of these |
| Answer» B. No | |
| 133. |
The turbine, in which the general direction of the steam flow is parallel to the turbine axis, is called axial flow turbines |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» B. False | |
| 134. |
Thermal equilibrium means that the flow of steam is |
| A. | isothermal |
| B. | isentropic |
| C. | hyperbolic |
| D. | polytropic |
| Answer» C. hyperbolic | |
| 135. |
The turbine blades do not change the direction of steam issuing from the nozzle. |
| A. | True |
| B. | False |
| C. | Can't say |
| D. | None of these |
| Answer» C. Can't say | |
| 136. |
The reheat factor is the ratio of the |
| A. | cumulative heat drop to the isentropic heat drop |
| B. | isentropic heat drop to the heat supplied |
| C. | total useful heat drop to the total isentropic heat drop |
| D. | none of the above |
| Answer» B. isentropic heat drop to the heat supplied | |
| 137. |
The critical pressure gives the velocity of steam at the throat equal to the velocity of sound. |
| A. | Agree |
| B. | Disagree |
| C. | Can't say |
| D. | None of these |
| Answer» B. Disagree | |
| 138. |
In_velocity_compounding_the_steam_is_expanded_from_the_boiler_pressure_to_condenser_pressure_in_one_set_of_stationary_blades_on_nozzle.$ |
| A. | True |
| B. | False |
| Answer» B. False | |
| 139. |
Which turbines are employed for driving alternator at synchronous speed? |
| A. | Central Station turbine |
| B. | Reheating turbine |
| C. | Extraction turbine |
| D. | Extraction induction turbine |
| Answer» B. Reheating turbine | |
| 140. |
Majority of the turbines are axial flow type. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 141. |
The turbine in which steam enters the blade tip nearest the axis of the wheel and flows towards the circumference is called _____________ |
| A. | axial flow turbine |
| B. | radial flow turbine |
| C. | impulse turbine |
| D. | non-condensing turbine |
| Answer» C. impulse turbine | |
| 142. |
In condensing turbine what is the back pressure of the turbine? |
| A. | Very high |
| B. | Above atmospheric pressure |
| C. | Equal to atmospheric pressure |
| D. | Below atmospheric pressure |
| Answer» E. | |
| 143. |
Reaction turbines are characterized by ___________ |
| A. | relatively low RPM and steam expension over nozzle |
| B. | relatively high RPM and steam expension over nozzle |
| C. | relatively low RPM and steam expension over rotor blades |
| D. | relatively high RPM and steam expansion over rotor blades |
| Answer» D. relatively high RPM and steam expansion over rotor blades | |
| 144. |
Which statement about reaction turbine is false? |
| A. | Steam does not expand in nozzle |
| B. | Blades acts like nozzles |
| C. | Steam expands as flows over the rotor blades |
| D. | Steam continuously losses its heat as flows over the rotor blades |
| Answer» E. | |
| 145. |
Which statement about impulse turbine is true? |
| A. | Steam expands over blades |
| B. | Steam expends completely in stationary nozzels |
| C. | Steam expends partially over nozzle and turbine blades |
| D. | Steam expends over blades incompletely |
| Answer» C. Steam expends partially over nozzle and turbine blades | |
| 146. |
Which of the following is not a type of steam turbine? |
| A. | Impulse turbine |
| B. | Reaction turbine |
| C. | Pelton wheel turbine |
| D. | Axial flow type turbine |
| Answer» D. Axial flow type turbine | |