Electrical interview question 11: Why Human body feel Electric shock ?? and in an Electric train during running , We did not feel any Shock ? why?
Answer: Unfortunately our body is a pretty good conductor of electricity, The golden rule is Current takes the lowest resistant path if you have insulation to our feet as the circuit is not complete (wearing rubber footwear which doing some repairs is advisable as our footwear is a high resistance path not much current flows through our body).The electric train is well insulated from its electrical system.
Electrical interview question 12 : What is the principle of motor?
Answer: Whenever a current carrying conductor is placed in an magnetic field it produce turning or twisting movement is called as torque.
Electrical interview question 13: Why, when birds sit on transmission lines or current wires doesn't get shock?
Answer: Its true that if birds touch the single one line (phase or neutral) they don't get electrical shock... if birds touch 2 lines than the circuit is closed and they get electrical shock.. so if a human touch single one line(phase) then he doesn't get shock if he is in the air (not touching - standing on the ground if he is standing on the ground then touching the line (phase) he will get a shock because the ground on what we standing is like line (ground bed - like neutral)। and in the most of electric lines the neutral is grounded..so that means that human who touch the line closes the circuit between phase and neutral.
Electrical interview question 14: What is meant by armature reaction?
Answer: The effect of armature flu to main flux is called armature reaction. The armature flux may support main flux or opposes main flux.
Electrical interview question 15: What happen if we give 220 volts dc supply to d bulb r tube light?
Answer: Bulbs [devices] for AC are designed to operate such that it offers high impedance to AC supply. Normally they have low resistance. When DC supply is applied, due to low resistance, the current through lamp would be so high that it may damage the bulb element.
Electrical interview question 16 : Which motor has high Starting Torque and Staring current DC motor, Induction motor or Synchronous motor?
Answer: DC Series motor has high starting torque. We can not start the Induction motor and Synchronous motors on load, but can not start the DC series motor without load.
Electrical interview question 17: What is ACSR cable and where we use it?
Answer: ACSR means Aluminium conductor steel reinforced, this conductor is used in transmission & distribution.
Electrical interview question 18: What is vaccum currcuit breaker.define with cause and where be use it Device?
Answer: A breaker is normally used to break a ciruit. while breaking the circuit, the contact terminals will be separated. At the time of seperation an air gap is formed in between the terminals. Due to existing current flow the air in the gap is ionised and results in the arc. various mediums are used to quench this arc in respective CB's. but in VCB the medium is vaccum gas. since the air in the CB is having vaccum pressure the arc formation is interrupted. VCB's can be used upto 11kv.
Electrical interview question 19: What will happen when power factor is leading in distribution of power?
Answer: If their is high power factor, i.e if the power factor is close to one:
1.losses in form of heat will be reduced,
2.cable becomes less bulky and easy to carry, and very cheap to afford, &
3. it also reduces over heating of transformers.
Electrical interview question 20: Whats the one main difference between UPS & inverter ? And electrical engineering & electronics engineering ?
Answer: Uninterrupt power supply is mainly use for short time . means according to ups VA it gives backup. ups is also two types : on line and offline . online ups having high volt and amp for long time backup with with high dc voltage.but ups start with 12v dc with 7 amp. but inverter is startwith 12v,24,dc to 36v dc and 120amp to 180amp battery with long time backup.
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