In power systems, the entire setup is divided into protective zones to isolate faults and protect the rest of the network. These zones include generators, transformers, buses, transmission lines, distribution lines, and motors. Each zone can be visualized as a separate room in a house, with each room protected by its own circuit breaker.
Protective zones are defined by closed dashed lines, containing one or more components. A key characteristic of these zones is the strategic placement of circuit breakers at the intersections of zones, ensuring that any fault within a zone can be isolated. For example, suppose a fault occurs in a zone analogous to a kitchen. In that case, the circuit breakers associated with that zone will open, isolating the fault and preventing it from affecting other areas.
Overlap between protective zones is crucial to ensure that no part of the system is left unprotected. This overlap is achieved by having two sets of instrument transformers and relays for each circuit breaker, providing redundancy. This redundancy ensures that even if one protection device fails, the other can still provide the necessary protection, enhancing the overall reliability and safety of the power system. This setup allows for the effective isolation of faults, maintaining the integrity and efficiency of the entire power network.
Effective protection schemes involve using different types of protective relays, such as differential, distance, and overcurrent relays, tailored to each zone's specific needs. Communication systems also play a vital role in coordinating the actions of protective devices, ensuring rapid and precise fault isolation. By implementing these strategies, power systems can achieve high levels of reliability and safety, minimizing disruptions and damage caused by faults.
