Yes, 35 kV lines can have busbar protection, typically implemented using differential or overcurrent-based schemes depending on system design and switchgear configuration.

Overview of Busbar Protection

Busbar protection is designed to detect and isolate faults on a busbar to prevent damage and maintain system stability. It operates by monitoring currents entering and leaving the busbar and quickly tripping the associated breakers if a fault is detected, often in less than 0.1 seconds for modern differential schemes . The protection ensures that only the faulty section is isolated, minimizing power interruptions and maintaining operational reliability .

Protection Methods

1. Differential Protection:
   • Measures the difference between incoming and outgoing currents using current transformers (CTs).
   • Can be low-impedance (percentage differential) or high-impedance, depending on the bus configuration and CT saturation considerations .
   • Provides fast fault clearance, which is critical for system stability and arc-flash hazard reduction.
2. Overcurrent-Based Protection:
   • Simpler and cost-effective, often used for distribution busbars where fault currents are lower.
   • May include interlocking schemes to coordinate with upstream and downstream protection .
3. Sectionalized Busbar Protection:
   • Divides the bus into zones, each with separate protection relays, allowing selective isolation of faults .

Application to 35 kV Systems

Medium-voltage switchgear rated for 35 kV, such as Eaton's Cooper Power series, is designed with main bus ratings and sectionalizing capabilities that allow integration of busbar protection . While not all 35 kV distribution systems automatically include busbar differential protection, it is common in critical or high-reliability installations, especially where multiple feeders or transformers are connected to a single bus. The protection can be implemented using numerical relays that handle multiple segments and provide adaptive trip logic to account for CT saturation and dynamic switching .

Conclusion

A 35 kV line can and often does have busbar protection, particularly in systems where fault isolation speed and selective tripping are important. The choice of protection—differential, overcurrent, or sectionalized—depends on the bus configuration, fault current levels, and operational requirements. Modern numerical relays make it feasible to implement reliable and fast busbar protection even in medium-voltage distribution networks .