Saturday, November 3, 2012

Off Campus Interview for a Fresher

These questions are given by one of our reader. He shared his experience. Please share yours...It is more informative if you mention the company name etc....
What is the Scope of Electrical Engineering?
[ This question is mostly asked to check your communication. Speak  casually. Tell the importance of electrical and electronics engineering course, what are the topics to be covered in the course, what are the job prospects etc.]

Answer: Electrical Engineering has a very broad scope with the science and technology which involves electricity, electronics, and electromagnetism in order to design, construct, and maintain products, services, and information systems.
Electrical Engineering is a branch that deals with the field associated with power transmission and motor control.
Electrical engineering  is one of the core fields of engineering, so it is always evergreen in terms of job prospects.
Electrical Engineering is the heart of whole engineering discipline.
Nowadays, we see  Electronics playing an important role in the implementation and control of Electrical Machines. Keeping this fact file in mind the course have transformed from core electrical Engineering into a Fusion of Electronics and Electrical and has been renamed as Electronics and Electrical engineering.
Electricity has become the basic need for survival, globally. From household to industrial plants, communication and satellite navigation system, electronic equipment, computers etc., all require electricity.
Electrical engineering thus deals with study and application of electrical systems for use in these different environments. It equips you with the knowledge of transmission and generation of electrical power, electrical circuit design, electronics, instrumentation, control system, understanding electrical and electronic networks etc.
The course also covers the study of electronic devices and circuits involved in measurement, instrumentation, control and protection of electrical equipments and conversion systems. Concept of computer and recent applications of computer based systems in design, analysis and efficient operation of power system, maintaining quality and security, also included in the course.

What does '230V AC Supply' really mean? Is it the RMS or peak voltage?
If the peak value is meant it should be clearly stated, otherwise assume it is the RMS value. The supply is 230V AC means 230V RMS, so the peak voltage of the mains is about 320V. 

What does the multimeter in volt meter mode show? Is it the RMS or peak voltage?
If the multimeter is in voltmeter mode and when it connects to AC circuits it shows the RMS value of the voltage or current. When it connects to varying DC signals it will show RMS value only.

How does Induction Motor work?
Induction motors are also known as rotating transformer.( Primary winding is stator and secondary winding is rotor).
When the 3 phase stator windings are fed by 3 phase supply a magnetic flux of constant magnitude, rotating at synchronous speed is generated. These flux passes through the air gap, sweeps past the rotor surface, cuts stationary rotor conductors.
According to Faraday's laws of electro-magnetic induction, an emf is induced in the rotor. This emf frequency is same as supply frequency.
As rotor conductors form a closed circuit, the induced emf produces a current. It's direction will oppose the cause producing it ( according to lenz's law). 
In this case, the cause is relative velocity between the rotating flux of the stator and stationary rotor conductors. So to reduce the relative speed, the rotor starts to run in the same direction of the stator flux.
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