Which of the following circuit breakers has the highest dielectric strength?

A. Bulk oil circuit breakers
B. air blast circuit breakers
C. Minimum oil circuit breakers
D. Vacuum circuit breakers

Answer
B. Air blast circuit breakers

Explanation 
Airblast circuit breaker used compressed air or gas as the arc interrupting medium. In the air blast, circuit breaker compressed air is stored in a tank and released through a nozzle to produce a high-velocity jet; this is used to extinguish the arc. 

Airblast circuit breakers are used for indoor services in the medium-high voltage field and medium rupturing capacity. Generally up to voltages of 15 kV and rupturing capacities of 2500 MVA. 

The air blast circuit breaker is now employed in high voltage circuits in the outdoors switchyard for 220 KV lines.



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 




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