Equipment connected to a 35kV single busbar

A 35kV single busbar typically connects incoming feeders, outgoing feeders, transformers, voltage transformers, protection devices, and monitoring equipment through switchgear and busbar assemblies.Core Components1. High-Voltage Switchgear 35kV single busbar systems use metal-enclosed, gas-insulated switchgear (GIS) or air-insulated switchgear (AIS) to connect circuits safely. Each feeder or transformer bay is equipped with a circuit breaker and isolators to control and isolate the connected equipment. Gas-insulated switchgear provides compact dimensions, high reliability, and long service life, often exceeding 35 years under normal operating conditions . 2. Busbars The busbar itself is a conductive copper or aluminum bar that distributes current from the incoming source to multiple outgoing circuits. It serves as the main node for current collection and distribution, ensuring low impedance and reliable connections. Busbars are designed considering current rating, short-circuit withstand, thermal rise, and mechanical support . 3. Incoming and Outgoing FeedersIncoming feeders bring power from upstream substations or generators.Outgoing feeders supply power to distribution networks, industrial loads, or other substations. Each feeder is connected via a circuit breaker and isolators to the busbar . 4. Transformers Power transformers may be connected to the busbar to step voltage up or down. Transformers are interfaced through circuit breakers, disconnectors, and protective relays to ensure safe operation and fault isolation. 5. Voltage Transformers (VTs) and Current Transformers (CTs) VTs and CTs are installed on the busbar or feeders for measurement, monitoring, and protection. They provide signals for SCADA systems, relay protection, and fault detection . 6. Cable Branch Boxes For distribution to multiple circuits, 35kV cable branch boxes with prefabricated copper busbars are used. These boxes allow one incoming circuit to branch into multiple outgoing circuits, with fully insulated, sealed, and maintenance-free construction. They may include live-line indicators, fault indicators, or surge arresters for monitoring and protection . 7. Protection and Monitoring DevicesOvercurrent and earth fault relaysArc suppression coils for single-phase-to-ground fault compensationBusbar grounding alarms and SCADA integration for real-time monitoring Operational ConsiderationsA single busbar system is simple and cost-effective, but it has low redundancy. Any fault on the busbar or maintenance requiring de-energization interrupts all connected circuits. Sectionalization with bus couplers can limit outage impact, but the system remains more exposed to bus faults compared to double-bus or ring-bus configurations .SummaryIn a 35kV single busbar setup, the main equipment includes:Circuit breakers and isolators for each bayIncoming and outgoing feedersTransformersVoltage and current transformersCable branch boxes for multi-circuit distributionProtection and monitoring devices such as relays, arc suppression coils, and SCADA interfaces This configuration is widely used in small to medium substations, industrial plants, and distribution networks where simplicity, compact layout, and cost efficiency are prioritized .