In this post, we will discuss the Top electrical Engineering Interview Questions and Answers. These questions and Answers may be helpful for your interview Preparation.
TOP ELECTRICAL Engineering Interview Questions and Answers
Q1. What are the different protection systems takes place on control panel board?
Answer: 1.Circuit Breaker
2.Fuse(over current protection)
4. Control panel body earthing(To prevent the body shorts)
5.Earthing (For drawn the Fault current which is higher than normal voltage)
Question2. what is the effect when the shunt field winding is opened in dc shunt motor
(i) at the time of starting?
(ii) in running condition?
Answer: Starting condition:
when the field winding is open means there is no production of the magnetic field, even though the armature carries the current (limited by the starter) there is no motoring action that’s why motor will not start.
suddenly the field disappears that’s why motor attains a very high speed so rotor may be damaged.
Question 3. what is the difference between base speed and rated speed in the motor?
Answer: Rated speed means the speed at full load and base speed means the speed in normal condition.
Question 4. what is the difference between fuse and breaker protection? which one is best?
Answer: Fuse and Breaker both are used for protection against short-circuit current. Fuse is used for low voltage protection say hospitals, homes, shops, schools etc. While the circuit breaker is used for mostly high voltage side say whole buildings, substations, factories, power grid, etc.
If we use circuit breaker instead of fuse it is not economical, maintenance & operating is also high. Fuse is easy to operate on a low voltage side.
So, Fuses are best suited for low voltage and small applications and Breakers are best suited for high voltage and large applications.
Question 5. why dc power cannot be used in a transformer?
Answer: Generally, transformer o/p is come by mutual induction i.e, flux produced in primary coil causes the flow of current in the secondary coil. mainly, flux is produced by time-varying fields i.e, AC signal since the ac signal is time variant but the dc signal is a time-invariant signal it is constant all the values of time. so, flux is not produced in the primary coil consequently no flow of current in the secondary coil and hence transformer action will not take place.
Question 6. Name the quantities which are not transformed in the transformer?
Question 7. What is electrical Transformer?
Answer: Its name is defined transformer because it transforms energy from one circuit to another circuit. Since it has no moving parts, so it is called a static device.
The transformer is a static device which step up or step-down the voltage with a constant frequency. There is no physical contact between the two winding. Transformer requires less maintenance as compared to other rotating devices.
When the transformer raises voltage higher than input voltage then it is called step up and when the transformer lowers the voltage lower than the input voltage is called step down.
Question 8. Define Construction of the transformer?
Answer: Transformer consists of a soft iron or silicon steel core and two winding names as,
primary winding & secondary winding
The windings are insulated to each other. A transformer tank is provided to support all assembly parts. The core is built up of thin soft iron and some percentage of silicon generally 0.35 to 0.4 % is added to reduce eddy current loss. The core is laminated each other to reduce iron loss. Electrical bushings are provided to connect winding terminals and external wire. Protecting device is provided to protect the transformer from overloading.
The windings are immersed with mineral oil for cooling. They are non-flammable and do not decompose to produce inflammable gasses. External cooling finned pipes are provided to cool transformer oil. Oil indicator provided to indicate oil level. Breather is provided to supply moisture free air to the transformer tank. A conservator tank provided to show oil level of the tank.
Question 9. Define Working Principle of Electrical Transformer?
Answer: The Transformer works on the principle of Faraday’s law of electromagnetic induction that is, The changing flux linkage is directly proportional to the induced EMF
If the secondary circuit is closed, a current flows through it, thus the electrical energy is transferred from the primary coil to the secondary coil.
Question 10. How do you maintain the earthing resistance?
Answer: Earthing Resistance can be maintained by adding water, charcoal & salt per month in the Earth Pit, Not only by adding these three, Its rusted bolt& Nuts must be renewed by a new one for every three months.
This maintenance should be varied depends upon the climatic conditions, such as in rainy season. Earth pit must be fence with cement.
Follow us on