PRIMARY AND SECONDARY OR BACKUP PROTECTION IN A POWER

Relay Protection and Power Plant Secondary Systems

This presentation reviews the established principles and the advanced aspects of the selection and application of protective relays in the overall protection system, multifunctional numerical devices application for power distribution and industrial systems, and. Recognized under 2(f) and 12 (B) of UGC ACT 1956 (Affiliated to JNTUH, Hyderabad, Approved by AICTE - Accredited by NBA & NAAC – 'A' Grade - ISO 9001:2015 Certified) Maisammaguda, Dhulapally (Post Via. Kompally), Secunderabad – 500100, Telangana State, India To introduce all kinds of circuit. Protective relays and devices have been developed over 100 years ago to provide "last line" of defense for the electrical systems. They are intended to quickly identify a fault and isolate it so the balance of the system continue to run under normal conditions. In HV (High Voltage) and MV (Medium Voltage) substations, relay protection safeguards critical assets such as transformers, circuit breakers, and lines. For example, unselective protection operation during a medium voltage network fault will cause an outage for an unnecessarily large number of consumers.

Cable primary and secondary distribution boxes

The equipment within these boxes varies: primary distribution cabinets usually contain isolating switches, circuit breakers, and residual current devices (RCDs); secondary cabinets contain large three-phase circuit breakers; tertiary cabinets contain single-phase circuit. Primary distribution systems consist of feeders that deliver power from distribution substations to distribution transformers. These boxes feature bottom entry and exit cables, front-opening doors, and main busbars connected with copper strips for optimal contact. Let's make a hypothesis: a newly built residential area introduces a 10kV incoming line and builds a distribution room. Understanding the fundamental distinction between Primary and Secondary distribution in electrical systems is pivotal for designing efficient and reliable electrical distribution systems tailored to specific needs across various domains.

Secondary distribution box connected to primary distribution box

The secondary distribution system is connected to the primary distribution system and is responsible for distributing the electricity to the end users. It operates at a low voltage level, which is stepped down by the distribution transformers. Let's make an example for clarity: A newly constructed residential area introduces a 10kV power line to a substation. In the first step, electricity is distributed to substations from the generating stations through transmission lines by increasing the voltage level to reduce transmission.

Top Protection of Primary Distribution Box

As with spot networks, network protectors are used to protect against primary feeder faults, and prevent fault current to propagate from the grid to the primary feeder.

Several power connection ports of the primary distribution box

Radial operation is the most widespread and most economic design of both MV and LV networks. It provides a sufficiently high degree of reliability and service continuity for most customers.

PRIMARY AND SECONDARY OR BACKUP PROTECTION IN A POWER

Relay Protection and Power Plant Secondary Systems

Cable primary and secondary distribution boxes

Secondary distribution box connected to primary distribution box

Top Protection of Primary Distribution Box

Several power connection ports of the primary distribution box

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