Protection In MV

Question 1

Why do we need protection?

Answer 1

Isolate faulty section, reduce damage, ensure safety and reliability

Question 2

Purpose of protection system?

Answer 2

Reduce hazard for people and property, reduce damage from fault, reduce risk of interruption, operate system closer to limits

Question 3

Types of fault

Answer 3

Active (Phase to phase), Passive (Partial discharge)

Question 4

What are Relay classifications?

Answer 4

Primary and Back Up

Question 5

Purpose of back up relaying?

Answer 5

Duplicate primary protection or to operate when primary fails

Question 6

Components of Protection System

Answer 6

Relays, CT, PT, Battery, Control Circuit

Question 7

Characteristics of Relays

Answer 7

Sensitivity, Selectivity, Speed, Simplicity, Economics

Question 8

Main requirement if System Protection

Answer 8

Speed(Limit risk/damage), sensitivity(limit risk/damage), Selectivity(limit further interruptions)

Question 9

Schemes of Protection

Answer 9

Unit scheme (specific to equipment), Non Unit scheme (Back up protection)

Question 10

Function of a relay

Answer 10

Electromagnetic switch turn on and off by a small current

Question 11

What type of system controls protection system? (generally)

Answer 11

DC control system