Protection:
The primary goal of protection in power systems is to detect and isolate faults promptly, preventing damage to equipment, minimizing downtime, and safeguarding personnel.
Protection is achieved by adjusting setting parameters to ensure sensitivity to the minimum short circuit current.
These parameters, based on rated full load current, starting current, inrush current, and through-fault current for the concerned equipment, incorporate a safety margin. This margin stabilizes protection settings for voltage variations, transients, asymmetricity, and temporary overloading.
Coordination:
Coordination enables protective devices to selectively respond to faults, ensuring that only the device closest to the fault operates, isolating the faulted section and allowing the rest of the system to continue operating normally. Selectivity prevents unnecessary tripping of healthy equipment. Rapid fault isolation prevents the propagation of disturbances, maintaining a stable operating condition in the system.
Coordination ensures that protection devices operate in a specific sequence, with upstream devices having longer time delays. This sequencing allows downstream devices to clear faults quickly, protecting downstream equipment from damage. Uncoordinated protection may lead to cascading failures, triggering a series of protective device operations and resulting in widespread outages. Coordination helps contain faults and prevent cascading failures.
Coordination, or selectivity, is ensured based on the maximum fault current in the system and is achieved using time grading and current grading concepts.