Bus bar protection scheme shall be provided for 220KV system where the sub-station layout arrangement is with 3-bus system (Main 1, Main 2 & Transfer Bus) or two bus system with Main bus with bus section breaker & Transfer bus.
Bus bar protection for two main bussystem shall also be provided wherever applicable. Bus bar protection for two main bus with one & Half breaker system shall also be provided wherever applicable.
Bus bar protection relaying scheme shall be provided in a separate simplex type panel with all bus differential relays, CT switching relays and trip relays etc. as required considering future bays.
Bus bar protection scheme shall be Numerical type and it shall have maximum operating time for all types of fault at five times set value is 25ms up to trip impulse to trip relay.
Bus Bar protection scheme
Operate selectively for each bus bar
Give hundred percent security up to 40 KA fault level for 400KV and 220KV and 31.5 KA for 132 KV
Incorporate continuous supervision for CT secondary against any possible open circuit and if it occurs, shall render the relevant zone of protection inoperative and initiate an alarm
Not give false operation during normal load flow in bus bars.
Incorporate clear zone indication.
Be of phase segregated and triple pole type
Provide independent zones of protection (including transfer bus if any). If the bus section is provided then each side of bus section shall have separate set of bus bar protection schemes
Include individual high speed hand reset tripping relays for each feeder ix) be transient free in operation
Include continuous D.C. supplies supervision.
Not cause tripping for the differential current below the load current of heaviest loaded feeder. Bidder shall submit application check for the same.
Shall include necessary C.T. switching relays wherever C.T. switching is involved and have ‘CT’ selection incomplete alarm
Include protection ‘IN/OUT’ switch for each zone
Include trip relays, CT switching relays (if applicable), auxiliary CTs (if applicable) as well as additional power supply modules, input modules etc. as may be required to provide a Bus-bar protection scheme for the complete bus arrangement.
For all the bay or breakers under this specification as well as for the future bays as per the Single line diagram for new substations. However for extension of bus bar protection scheme (if specified in BPS) in existing substations, scope shall be limited to the bay or breakers covered under this specification. Suitable panels to mount these are also included in the scope of the work.
Built-in Local Breaker Backup protection feature as a part of bus bar protection scheme shall also be acceptable.
At existing substations, Bus-bar protection scheme with independent zones for each bus, will be available. All necessary co-ordination for ‘AC’ and ‘DC’ interconnections between existing schemes (Panels) and the bays proposed under the scope of this contract shall be fully covered by the bidder.
Any auxiliary relay, trip relay, flag relay and multi tap auxiliary CTs (in case of biased differential protection) required to facilitate the operation of the bays covered under this contract shall be fully covered in the scope of the bidder.
Short Question on Bus bar protection
What is a busbar in an electrical substation?
A busbar is a metallic strip or bar used to conduct electricity within an electrical substation. It acts as a common connection point for multiple incoming and outgoing electrical circuits.
Why is busbar protection necessary in electrical substations?
Busbar protection is necessary to ensure the reliable operation of the electrical substation. It protects the busbar from faults such as short circuits or phase-to-phase faults, which could lead to equipment damage, power interruptions, or even safety hazards.
What are the different types of busbar protection schemes?
Busbar protection schemes can be categorized into:
- Differential Protection: Compares currents entering and leaving the busbar to detect internal faults.
2.Overcurrent Protection: Monitors current levels to detect abnormal conditions indicating a fault.
3.Impedance Protection: Uses the impedance measurement to detect faults based on changes in impedance values.
What are the typical types of busbar faults that protection systems need to detect?
Busbar protection systems need to detect faults such as phase-to-phase faults (L-L faults), phase-to-ground faults (L-G faults), busbar faults caused by insulation failures, and faults due to accidental contact with foreign objects.
How does busbar protection work?
Busbar protection systems typically use current and voltage measurements at various points along the busbar to detect faults. Algorithms analyze these measurements to distinguish between normal operating conditions and fault conditions. Upon detecting a fault, the protection system initiates a trip signal to isolate the affected section of the busbar.
What are the primary components of a busbar protection scheme?
A busbar protection scheme generally includes:
Current transformers (CTs) to measure current flowing through the busbar.
Voltage transformers (VTs) to measure the voltage across the busbar.
Protective relays to process CT and VT inputs, detect faults, and issue trip commands.
Circuit breakers or disconnectors to isolate the faulty section of the busbar.
How does differential protection for busbars work?
Differential protection compares the currents entering and leaving the protected zone (busbar) using current transformers. If there is a significant imbalance indicating a fault, the differential relay issues a trip signal to isolate the busbar.
What are the challenges in implementing busbar protection?
Challenges include ensuring proper coordination with other protection systems, accurately setting protection relay settings, addressing system grounding issues, and dealing with high fault currents in large substations.