search
person

1 Answer

Transformer efficiency is maximum when copper losses are equal to iron losses.
thumb_up_alt 0 like thumb_down_alt 0 dislike

Related questions

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

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

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

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

Description : If a transformer is continuously operated the maximum temperature rise will occur in?

Answer : If a transformer is continuously operated the maximum temperature rise will occur in windings.

Description : Transformer efficiency

Answer : Transformer efficiency

Description : A transformer operates 24 hours day at full -load. It's full -load efficiency is :  (A) equal all day efficiency (B) more than all -day efficiency (C) less than all -day efficiency (D) equal to maximum efficiency

Answer : A transformer operates 24 hours day at full -load. It's full -load efficiency is : equal all day efficiency 

Answer : The efficiency of transformer is Greater than electrical Machine because there is no rotational losses in transformer and there is no air gap losses in transformer so losses is less in transformer compare to electrical machine so efficiency is higher in case of transformer.

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%.

Answer : The efficiency of a power transformer is of the order of 98 percent.

Description : The efficiency of a transformer, under heavy loads, is comparatively low because?

Answer : The efficiency of a transformer, under heavy loads, is comparatively low because copper loss becomes high in proportion to the output.

Description : The maximum load that a power transformer can carry is limited by its?

Answer : The maximum load that a power transformer can carry is limited by its voltage ratio.

Answer : The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is 0.5.

Description : The synchronous motor will develop maximum power when the load angle is?

Answer : The synchronous motor will develop maximum power when the load angle is 900.

Answer : The maximum efficiency of a distribution transformer is at 50% full load.

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.

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

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.

Description : The efficiency of two identical transformers under load conditions can be determined by?

Answer : The efficiency of two identical transformers under load conditions can be determined by back-to-back test.

Description : The maximum constant load torque under which a synchronous motor will pull into synchronism at rated rotor supply voltage and frequency is known as?

Answer : The maximum constant load torque under which a synchronous motor will pull into synchronism at rated rotor supply voltage and frequency is known as pull-in torque.

Description : The maximum torque which a synchronous motor will develop at rest for any angular position of the rotor, at rated stator supply voltage and frequency, is known as?

Answer : Power plant having maximum demand more than the installed rated capacity will have utilisation factor more than unity.

Description : "Maximum power output is obtained from a network when the load resistance is equal to the output resistance of the network as seen from the terminals of the load". The above statement is associated with?

Answer : "Maximum power output is obtained from a network when the load resistance is equal to the output resistance of the network as seen from the terminals of the load". The above statement is associated with Maximum power transfer theorem.

Answer : In repulsion motor, maximum torque is developed when brush axis is at 45° electrical to the field axis.

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 : "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 : When secondary of a current transformer is open-circuited its iron core will be?

Answer : When secondary of a current transformer is open-circuited its iron core will be hot because of heavy iron losses taking place in it due to high flux density.

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

Answer : For maximum transfer of power, internal resistance of the source should be equal to load resistance.

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 :  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 : What is the efficiency of Class-B amplifier?  A) 68.50% B) 78.50% C) 88.50% D) 98.50%

Answer : What is the efficiency of Class-B amplifier?  A) 68.50% B) 78.50% C) 88.50% D) 98.50%

Description : The overall efficiency of Thermal Power Plant is equal to _______________ .  (A) Regenerative Cycle Efficiency (B) Renkine Cycle Efficiency (C) Carnot cycle efficiency (D) None of the above

Answer : The overall efficiency of Thermal Power Plant is equal to Regenerative Cycle Efficiency. 

Description : The rankine cycle efficiency of steam power plant is  (1) 60-80% (3) 30-45% (2) 45-80% (4) 20-30%

Answer : The rankine cycle efficiency of steam power plant is 30-45%

Description : Transmission efficiency of a transmission line increases with the

Answer : Transmission efficiency of a transmission line increases with the increase in power factor and voltage

Answer : The efficiency of diesel locomotives is nearly 20 to 25 percent.

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

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

Description : Which motor have more efficiency, synchronous motor or induction motor?

Answer : Synchronous motor has more efficiency.

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

Description : Define : i) Maximum Value ii) RMS Value of ac supply

Answer : i) Maximum Value :- The maximum or peak value attained by an alternating quantity during positive or negative half cycle, is called maximum value or peak value.  ii) RMS Value of ac ... as produced by the alternating current when flowing through the same resistance and for the same time. 

Description : Define the following terms: 1) Virtual height 2) Actual height 3) Critical frequency. 4) Maximum usable frequency.

Answer : 1) Virtual height:- The incident and refracted rays follow paths that are exactly the same as they have been if reflection had taken place from a surface located at a greater height, called ... angle of incidence is other than the normal is known as maximum unstable frequency. MUF= fc secθ 

Description : Maximum Power Transfer Theorem 1

Answer : Maximum Power Transfer Theorem 1

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.

Description :  An independent voltage source in series with an impedance ZS=R+jXS delivers a maximum average power to a load impedance ZL when A) ZL = R B) ZL = jXS C) ZL = R-jXS D) ZL = R+jXS 

Answer :  An independent voltage source in series with an impedance ZS=R+jXS delivers a maximum average power to a load impedance ZL when ZL = R-jXS

Description : The kVA rating of Three-phase transformer with Voltage = 200V and Current = 100A will be :  (A) 34.64 kVA (B) 75 kVA (C) 20 kVA (D) None of the above

Answer : The kVA rating of Three-phase transformer with Voltage = 200V and Current = 100A will be : 34.64 kVA

Answer : In a transformer, routine efficiency depends upon load current and power factor of load.

Description : A certain power MOSFET has a maximum junction temperature specification of 1500o C, a junction-to-case thermal resistance of 1.00 C/W, and a junction-to ambient thermal resistance of 600 C/W. If the ambient temperature is 300o C ... the device will be A) 1.52 W B) 1.72 W C) 1.92W D) 2.00 W

Answer : A certain power MOSFET has a maximum junction temperature specification of 1500o C, a junction-to-case thermal resistance of 1.00 C/W, and a junction-to ambient thermal resistance of  ... 300o C, then the maximum allowable power dissipation in the device will be 2.00 W 

Description : The maximum reluctance power of a salient-pole synchronous motor having direct-axis reactance, 1.0 pu and quadrature-axis reactance, 0.5 pu, and input voltage, 1.0 pu is (A) 0.25 pu (B) 0.5 pu (C) 1.0 pu (D) 1.5 pu

Answer : The maximum reluctance power of a salient-pole synchronous motor having direct-axis reactance, 1.0 pu and quadrature-axis reactance, 0.5 pu, and input voltage, 1.0 pu is 0.5 pu

← Prev Question Next Question →
editAsk a Question
...