Electronics and
Electrical Engineering interview Question and Answers for fresh engineers (Part
3)
Question 11: What are the
electric supply system classification and principle components?
In this topic we know about ,electric supply system,electric supply system classification and principle components,components are used for dc to ac convert or ac to dc convert
Question 10: What is electric supply system?
Answer 10: Electric
supply system: The process of transporting or conveyance of electrical energy or power from a power
station to the users premises (home, industry etc) is called as electric supply
system.
Question 11: What are the
electric supply system classification and principle components?
Answer 11: The electric supply system can be classified into two
types:
і) AC or DC
supplies system.
ii) Underground or Overhead Supply system.
In
the electric supply system the 3 phase 3 wire system is used for AC energy
generation and transmission. In the distribution system three phase four wires
is used now a days. This system is now used all over the world.
In the underground system
tunnels are used and in overhead system poles are used.
Question 12: Which
components are used for dc to ac convert or ac to dc convert? What is the
operation range of these devices? What is present day’s trend for generation
and transmission?
Answer 12: The high
voltage dc transmission is much better than the high voltage ac transmission.
So, now the electrical engineers grow interest for transmission of dc in place
of ac.
The
use of Mercury arc rectifiers and thyratron gives opportunities
of converting a.c into d.c and the conversion of dc to ac to the electrical
engineers.
 |
| Figure: One line diagram for the high voltage dc transmission |
In the given one line diagram the electrical power is generated as ac and
stepped up to high voltage by the help of stepper transformer. Then this high
voltage energy is transferred to the Mercury arc rectifiers, which
change ac to dc. After that time this high voltage dc is passed through the thyratron,
this thyratron convert dc to ac again. After that this high voltage is
stepped down to low voltage in receiving transformer.
The
operation range of such devices is up to 30MW at 400KV in one single unit.
The
present trend is using ac for generation and distribution. And the dc is used for high voltage transmission.
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