search
person

1 Answer

D.C. generators are normally designed for maximum efficiency around full-load.

thumb_up_alt 0 like thumb_down_alt 0 dislike

Related questions

Answer : Generators for peak load plants are usually designed for maximum efficiency at 50 to 75 percent full load.

Answer : The condition for maximum efficiency for a D.C. generator is variable losses equal to constant losses.

Answer : The efficiency of a properly designed synchronous motor will usually fall in range 85 to 95%.

Answer : If  equalising bar is connected to the 2 DC generators  the current will be equal in 2 generators irrespective of parallel connection so that we connect equaliser bar

Answer : Compensating windings are used in D.C. generators to neutralise the cross-magnetising effect of the armature reaction.

Answer : D.C. generators are connected to the busbars or disconnected from them only under the floating condition to avoid sudden loading of the primemover, to avoid mechanicaljerk to the shaft, to avoid burning of switch contacts.

Answer : In D.C. generators the pole shoes are fastened to the pole core by counter sunk screws.

Answer : D.C. generators are installed near the load centres to reduce line losses.

Answer : For the parallel operation of two or more D.C. compound generators, we should ensure that series fields of all generators should be either on positive side or negative side of the armature.

Description : For a transformer, operating at constant load current, maximum efficiency will occur at?

Answer : For a transformer, operating at constant load current, maximum efficiency will occur at unity power factor.

Answer : In D.C. generators the polarity of the interpoles is the same as that of the main pole ahead.

Answer : In D.C. generators, the brushes on commutator remain in contact with conductors which lie under interpolar region.

Answer : In D.C. generators, current to the external circuit from armature is given through commutator commutator.

Answer : An ideal transformer will have maximum efficiency at a load such that copper loss equal to iron loss.

Answer : Transformer efficiency is maximum when copper losses are equal to iron losses.

Description : In DC generators lamination core are generally made of?

Answer : In DC generators lamination core are generally made of silicon steel.

Description : Identify the increasing order of voltage regulation of the following dc generators a same load :  (A) differential compound, shunt and under compound  (B) shunt, differential compound and ... C) under compound, shunt and differential compound  (D) shunt, under compound and differential compound

Answer : Identify the increasing order of voltage regulation of the following dc generators a same load : under compound, shunt and differential compound 

Description : State maximum power transfer theorem for DC circuit.

Answer : Maximum power transfer theorem for DC circuit: The maximum power transfer theorem states that the source or a network transfers maximum power to load only when the load resistance is equal ... removed (disconnected) ii) All internal independent sources are replaced by their internal resistances.

Answer : Series motor has got maximum self relieving property.

Answer : In a D.C. shunt motor, under the conditions of maximum power, the current in the armature will be more than full-load current.

Description : Phase modifier is normally installed

Answer : Phase modifier is normally installed in case of long lines

Description : If the load of the normally excited synchronous motor is increased the power factor will?

Answer : If the load of the normally excited synchronous motor is increased the power factor will become lagging.

Answer : Air blast circuit breakers for 400 kV power system are designed to operate in 50 millisecond.

Answer : The overall efficiency of steam locomotive is around 5 to 10 percent.

Description : Explain the lighting scheme to be designed for each of the following: i) Special ward in hospitals ii) Dentist’s Cabin 

Answer : i) Special ward in hospital: For the patients in the wards, lighting should create a cozy and pleasant atmosphere. Lighting in the wards should be planned in such a way that it meets the specific ... we use such as cements and bonding agents that we use to restore your teeth back to health.

Description : What would happen if a power transformer designed for operation on 50 Hz (frequency) were connected to a 500 Hz (frequency) source of the same voltage:  (A) Eddy Current and Hysteresis losses will be ... Current will be too much high  (C) Transformer may start to smoke and burn  (D) No effect

Answer : What would happen if a power transformer designed for operation on 50 Hz (frequency) were connected to a 500 Hz (frequency) source of the same voltage:  (A) Eddy Current and Hysteresis losses will be ... will be too much high  (C) Transformer may start to smoke and burn  (D) No effect

Answer : Overhead system can be designed for operation up to 400 kV.

Description : Why are generators rated in kVA not in kW ?

Answer : Because It's rating of generator kva is apparent power. Kw is active power which we use. And one is kvar reactive power.

Description : Two synchronous generators G1, G2 are operating in parallel and are equally sharing KVAR (Lag) component of load. To shift part of KVAR from G2 to G1, while keeping terminal voltage fixed, the following action must be done

Answer : Two synchronous generators G1, G2 are operating in parallel and are equally sharing KVAR (Lag) component of load. To shift part of KVAR from G2 to G1, while keeping terminal voltage fixed, the following action must be done Raise If1 and lower If2

Answer : Large capacity generators are invariably hydrogen cooled.

Answer : Distribution transformers are generally designed for maximum efficiency around 50% load.

Description : A circuit breaker is designed to protect an electrical circuit from damage caused by :  (A) Over load (B) Short circuit (C) Over current (D) All of the above

Answer : A circuit breaker is designed to protect an electrical circuit from damage caused by :  (A) Over load (B) Short circuit (C) Over current (D) All of the above

Answer : An efficient and a well designed protective relaying should have good selectivity and reliability, economy and simplicity, high speed and selectivity.

Answer : Relays can be designed to respond to changes in resistance, reactance or impedance voltage and current, light intensity, temperature.

Answer : In D.C. generators on no-load, the air gap flux distribution in space is flat topped.

Description : Two synchronous generators operating in parallel supply a common load of 2.5 MW. The frequency-power characteristics have a common slope of 1 MW/Hz and the no-load frequencies of the generators are 51.5 Hz and 51.0 Hz, ... system frequency is (A) 50 Hz (B) 51 Hz (C) 51.25 Hz (D) 51.5 Hz

Answer : Two synchronous generators operating in parallel supply a common load of 2.5 MW. The frequency-power characteristics have a common slope of 1 MW/Hz and the no-load frequencies of the generators are 51.5 Hz and 51.0 Hz, respectively. Then the system frequency is 50 Hz

Answer : Power transformers are generally designed to have maximum efficiency around near full-load.

Answer : The total losses in a well designed D.C. generator of 10 kW will be nearly 500 W.

Answer : In case the conditions for maximum power for a D.C. motor are established, the efficiency of the motor will be less than 50%.

Description : method for improving string efficiency 

Answer : The Methods of Improving String Efficiency:-   1) By reducing value of ‘m’ or (‘k’) by using longer cross arm. 2) By Making of ‘m’ or (‘k’) equal to zero 3) By grading Insulator. 4) By Using guard ring.

Description : For high efficiency of transfer of power, internal resistance of the source should be?

Answer : For high efficiency of transfer of power, internal resistance of the source should be less than the load resistance.

Answer : The range of efficiency for shaded pole motors is 5% to 35%.

Answer : String efficiency is used for measuring the degree of utilization of SCR.

Description : SEER: Seasonal Energy Efficiency Ratio (SEER)

Answer : SEER: Seasonal Energy Efficiency Ratio (SEER), is most commonly used to measure the efficiency of a central air conditioner. The higher the SEER, the more efficient the system OR It is the ... the ratio of total capacity to the total KW energy usage at specific humidity and temperature condition.

Description : State why a transformer always have an efficiency of more than 90%.

Answer : As transformer is static device with no moving parts, the losses due to friction & windage are completely absent. Hence transformer has efficiency of more than 90%.

Description :  Compare the salient features of LED and CFL based on: i] Lamp Efficiency ii] Life span 

Answer : Parameter LED CFL Lamp Efficiency  High (more than 70 lumen per watt) Comparatively less (50-60 lumen per watt) Life span (in working hours) 10000 3000

Description : Define PIV, TUF, ripple factor, efficiency of rectifier.

Answer : PIV: Peak Inverse Voltage (PIV) is defined as the maximum negative voltage which appears across non-conducting reverse biased diode. TUF : Transformer Utilization Factor (TUF) is defined as the ratio of DC output ... Efficiency of rectifier: η = DC output power/ AC input power = PLdc / Pac

Description : "Efficiency of thermal power station is low". — Justify. 

Answer : Justification: Efficiency of thermal power station is low":- Overall efficiency of T.P.P depends upon efficiency of boiler, turbine and alternator. The heat produced due to combustion of coal ... losses in thermal power plant is 71%, So efficiency of thermal power plant is less about 29% 

Description : Transformer efficiency

Answer : Transformer efficiency

← Prev Question Next Question →
editChoose topic
...