In a transformer, which of the following losses are zero?

(a) Hysteresis losses.

(b) Eddy's current losses.

(c) Copper losses.

(d) Frictional and windage losses.

Answer

(d) Frictional and windage losses.

Explanation:

• Friction losses are involved with rotating parts of a machine. 
• Since in a transformer all parts are stationary, friction losses will always be equal to zero, irrespective of the loading condition.
• A transformer is a static device i.e. transformer does not consist of any type of moving component, due to which there is no frictional loss in the transformer.
• Hence the efficiency of the transformer is highest among the all other electrical devices. It is generally more than 90%.
• The transformer works on the principle of Faraday’s Electromagnetic Induction.
• The sum of eddy current loss & hysteresis loss is known as iron loss or core loss, which are occurred in the core of the transformer.
• An open circuit test is performed to calculate the iron or core losses of the transformer.
• A short circuit test is used to find a copper loss in the transformer.

Power System MCQs With Explanation 

 

• The advantages of high transmission voltage are
• The charging current drawn by the cable is
• The fact that current density is higher at the surface when compared to the center is known as
• In which of the following transmission lines capacitance effect is negligible?
• The distribution constant of the transmission line is
• Proximity effect is more in case of
• If the frequency is increased, then the skin effect will
• Bundled conductors in EHV transmission lines help in
• Which of the following produces radio interference in communication lines?
• Telecommunication lines are transposed to reduce the
• What is the function of economizer in Thermal Power Plant 
• Which of the following effects are associated with transmission line
• The insulator thickness on the conductor, in cables, depends upon
• By using a guard ring in a transmission line, its string efficiency
• If sag in an overhead line increase, the tension in the line
• Corona is accompanied by
• The conductor carries more current on the surface as compared to the core. This is called as
• Critical disruptive voltage is a voltage at which
• Bundled conductors are used for EHV transmission lines primarily for reducing the
• Low power factor is usually not due to
• Bonding is done at both ends of the cable to reduce the
• For Improving power factor
• Stock bridge dampers are used to
• Which of the following insulator is practically used for railway crossings?
• Which of the following decides the insulation level of 400 kV, EHV line?
• When earth fault occurs
• The minimum length of pipe electrode used for earthing should not be less than
• A ground wire is used to
• Earth resistance in typical domestic wiring is
• By which of the following systems electric power may be transmitted?
• Which of the following equipment will be most economical for regulating the voltage in the distribution feeder?

Transformer MCQs With Explanation 

• In a transformer the primary flux is 
• The noise of the transformer is mainly due to
• Buchholz relay is used for the protection
• Iron loss in a transformer can be determined by
• Oil is provided in an oil-filled transformer for
• In a star-delta transformer, the delta side phase voltage leads the star sides phase voltage by an angle
• Minimum voltage regulation occurs in transformer when the power factor of the load is
• The chemical used in the breather of a transformer should have the property of
• The power transformer can be termed as a constant
• In a transformer, which of the following losses are zero?
• Which of the following Transformer can have a tap changer?
• If the supply frequency (f) of a transformer decreases, the effect of frequency on the transformer's secondary output voltage?
• The primary winding of a transformer has a 120 V ac supply. What is the value of secondary voltage if the turn ratio is 10?
• The efficiency of a power transformer is _____ at full load.
• In a transformer the relation between the input frequency and the output voltage on secondary winding is _____.
• In a current transformer, _____ winding is closed.
• A transformer is a _____ device.
• A step-down transformer has _____ number of turns on primary winding and _____ number of turns on the secondary winding.
• A step-up transformer has _____ number of turns on primary winding and _____ number of turns on the secondary winding.
• Transformer works on ______ principle.
• Shell Type Transformer is mainly used for 
• A Magnetic Oil level Guage (MOG) is used in the Transformer to 
• The Function Of Power Transformer is/are
• The Radiators are used in transformers for 

Synchronous Motor MCQs With Explanation 

• In 3 -Φ synchronous motor if one of the phases is short-circuited the motor will
• The speed regulation of a synchronous motor is
• The negative phase sequence in a three-phase synchronous motor exists when the motor is
• What happens if the field winding of the synchronous motor is short-circuited?
• For power factor correction, synchronous motors operate at

Induction Motor MCQs With Explanation 

• In a capacitor start and run the motor the function of the running capacitor in series with the auxiliary winding is to
• A split-phase motor has
• If the capacitor of a single-phase motor is short-circuited
• In a split-phase motor, the running winding should have

• Power System MCQs With Explanation 

   

  • The advantages of high transmission voltage are
  • The charging current drawn by the cable is
  • The fact that current density is higher at the surface when compared to the center is known as
  • In which of the following transmission lines capacitance effect is negligible?
  • The distribution constant of the transmission line is
  • Proximity effect is more in case of
  • If the frequency is increased, then the skin effect will
  • Bundled conductors in EHV transmission lines help in
  • Which of the following produces radio interference in communication lines?
  • Telecommunication lines are transposed to reduce the
  • What is the function of economizer in Thermal Power Plant 
  • Which of the following effects are associated with transmission line
  • The insulator thickness on the conductor, in cables, depends upon
  • By using a guard ring in a transmission line, its string efficiency
  • If sag in an overhead line increase, the tension in the line
  • Corona is accompanied by
  • The conductor carries more current on the surface as compared to the core. This is called as
  • Critical disruptive voltage is a voltage at which
  • Bundled conductors are used for EHV transmission lines primarily for reducing the
  • Low power factor is usually not due to
  • Bonding is done at both ends of the cable to reduce the
  • For Improving power factor
  • Stock bridge dampers are used to
  • Which of the following insulator is practically used for railway crossings?
  • Which of the following decides the insulation level of 400 kV, EHV line?
  • When earth fault occurs
  • The minimum length of pipe electrode used for earthing should not be less than
  • A ground wire is used to
  • Earth resistance in typical domestic wiring is
  • By which of the following systems electric power may be transmitted?
  • Which of the following equipment will be most economical for regulating the voltage in the distribution feeder?
  
  

  Transformer MCQs With Explanation 

  
  
  • In a transformer the primary flux is 
  • The noise of the transformer is mainly due to
  • Buchholz relay is used for the protection
  • Iron loss in a transformer can be determined by
  • Oil is provided in an oil-filled transformer for
  • In a star-delta transformer, the delta side phase voltage leads the star sides phase voltage by an angle
  • Minimum voltage regulation occurs in transformer when the power factor of the load is
  • The chemical used in the breather of a transformer should have the property of
  • The power transformer can be termed as a constant
  • In a transformer, which of the following losses are zero?
  • Which of the following Transformer can have a tap changer?
  • If the supply frequency (f) of a transformer decreases, the effect of frequency on the transformer's secondary output voltage?
  • The primary winding of a transformer has a 120 V ac supply. What is the value of secondary voltage if the turn ratio is 10?
  • The efficiency of a power transformer is _____ at full load.
  • In a transformer the relation between the input frequency and the output voltage on secondary winding is _____.
  • In a current transformer, _____ winding is closed.
  • A transformer is a _____ device.
  • A step-down transformer has _____ number of turns on primary winding and _____ number of turns on the secondary winding.
  • A step-up transformer has _____ number of turns on primary winding and _____ number of turns on the secondary winding.
  • Transformer works on ______ principle.
  • Shell Type Transformer is mainly used for 
  • A Magnetic Oil level Guage (MOG) is used in the Transformer to 
  • The Function Of Power Transformer is/are
  • The Radiators are used in transformers for 

  
  

  
  

  
  
  
  

  Synchronous Motor MCQs With Explanation 

  
  
  • In 3 -Φ synchronous motor if one of the phases is short-circuited the motor will
  • The speed regulation of a synchronous motor is
  • The negative phase sequence in a three-phase synchronous motor exists when the motor is
  • What happens if the field winding of the synchronous motor is short-circuited?
  • For power factor correction, synchronous motors operate at
  
  

  Induction Motor MCQs With Explanation 

  
  

  • In a capacitor start and run the motor the function of the running capacitor in series with the auxiliary winding is to
  • A split-phase motor has
  • If the capacitor of a single-phase motor is short-circuited
  • In a split-phase motor, the running winding should have