The document discusses bus bar protection in substations, highlighting its importance in safeguarding against faults that can cause widespread disruptions and damage. It outlines the design and operational requirements for effective bus bar protection, including the necessity for high-speed, selective, and reliable systems, particularly in new and existing high voltage substations. Key technical concepts, such as Kirchoff’s current law and the types of bus bar protection, are also covered.

1. BUS BAR PROTECTION
Sumeet Ratnawat
NCA Indore

3. OBJECTIVE OF STATION PROTECTION
 To protect all such elements or sections in
a substation which are not covered either
under line protection or equipment
protection
Station protection include
 Bus Bar protection
 LBB(Local Breaker back-Up) protection

4. CT CORES
 CORE 1  BUS BAR CHECK ZONE
 CORE 2  BUS BAR MAIN ZONE
 CORE 3  METERING
 CORE 4  MAIN I LINE PROTECTION
 CORE 5  LBB & MAIN II LINE
PROTECTION

5.  In Absence Of BUSBAR Protection,
Fault Clearance takes place
in Zone II of Distance Relay by
Remote End Tripping
 This Means Slow & Unselective Tripping
and wide spread blackout
NEED FOR BUS BAR PROTECTION

6.  Minimizing damage at fault location
 Maintaining system stability
 Localizing isolation to avoid wide
spread disruption
 Delayed clearance create shock to inter
connected equipment like Generator shaft
and windings of Transformer
NEED FOR BUS BAR PROTECTION

7.  High speed operation
 Selectivity – shall isolate the faulty bus bar only
 Stability – stable for through faults upto 40 KA
fault level
 Reliability – Check feature
 Applicable for any type of bus bar protection
 Shall provide zone indication
REQUIREMENT OF BUS BAR PROTECTION

8.  Continuous supervision for CT Secondaries
against any possible Open Ckt.
 In case of detection of any Open Circuiting of CT
secondary, after a time delay, the affected zone
of protection shall be rendered(provide) in-
operative and an alarm initiated.
REQUIREMENT OF BUS BAR PROTECTION

9.  Bus bar protection must be provided in all new 400kV and
220kV Substations as well as Generation Switch Yards
 For existing substations, provision of bus bar protection is
considered a must at 400kV level and for 220kV level it is
essential at substations having multiple feed.
 In case of radially fed 220kv substations, having more
than one bus it is desirable to have bus bar protection but
is not a must
RECOMMENDATIONS FOR PROVIDING BUS BAR
PROTECTION

10. BASICS OF BUSBAR PROTECTION
NEED FOR BUSBAR PROTECTION
In Its Absence Fault Clearing Takes Place In Zone-2 Of Distance Relay By Remote End Tripping. this means
slow and unselective tripping and wide spread blackout.
EFFECT OF DELAYED CLEARENCE
 Greater damage at fault point.
 Indirect shock to connected equipment like shafts of generator and windings of transformer.
BASIC THEORY
Kirchoff’s current law states that the sum of the currents entering a given node must be equal to the currents
leaving at that node.

11. TYPES OF BUS BAR PROTECTION
 Low Impedance
 High Impedance
Both use Circulating Current Differential
Principle - To isolate the entire bus bar section
by disconnecting all the feeders connected to
the bus.

12. HIGH SPEED DIFFERENTIAL PROTECTION
Simple Current Differential Circuit:

13. Simple Current Differential Circuit with Bus Fault

14. Simple Current Differential Circuit with Close in Line Fault

15. Simple Current Differential Circuit with Restraint Coils and a Close
Line in Fault
Simple

16. High Impedance Differential Relays ( Only Phase A shown)

17. Supervisory Circuit for Checking Bus Differential Protection

18. Typical Instantaneous Over-current Relay

19. IDMT Characteristic of a Relay