For small busbars in Serbia, low-impedance differential relays like Toshiba GRB100 or GE B90, and high-impedance or distributed protection IEDs from Hitachi Energy, provide reliable, low-noise busbar protection.

Key Considerations for Small Busbar Protection

1. Protection Type:

• Low-impedance differential relays (e.g., Toshiba GRB100) are ideal for small busbars, offering fast fault detection and clearance with minimal noise due to precise current comparison and optional CT saturation countermeasures .
• High-impedance schemes (e.g., GE B90) are suitable for applications where CT mismatches or long feeder runs exist, providing sub-cycle tripping and low operational noise .
• Distributed protection IEDs (Hitachi Relion series) allow flexible deployment across small busbars, supporting both phase-to-phase and phase-to-earth faults with fast clearance and low electromagnetic interference . 2. Busbar Configuration:
• Single, double, one-and-a-half, or ring busbars can be protected using these relays. Centralized or decentralized architectures are available depending on the substation layout .
• Phase-segregated protection ensures selective fault isolation, reducing unnecessary tripping and operational noise . 3. Noise Reduction Features:
• Modern numerical relays minimize mechanical noise by eliminating electromechanical components.
• Optional undervoltage fault detectors and CT saturation countermeasures reduce false trips and associated relay actuation noise .
• Sub-cycle tripping times (as low as 0.75 cycles in B90) reduce prolonged fault currents, further limiting acoustic and electromagnetic noise . 4. Additional Functionalities:
• Integrated metering, data recording, and communication capabilities allow monitoring without additional noisy devices .
• Circuit breaker failure protection and optional remote control enhance reliability while maintaining low operational noise. 5. Implementation Tips:
• Ensure proper CT selection and ratio matching to avoid false differential currents.
• For small busbars, centralized low-impedance relays are often simpler and quieter, while distributed IEDs provide flexibility for complex layouts.
• Compliance with IEC61850 standards ensures interoperability and future-proofing .

Recommended Solutions

• Toshiba GRB100: Low-impedance differential relay, suitable for single or double busbars, low-noise operation, optional undervoltage and breaker failure protection .
• GE B90: High-impedance bus protection, sub-cycle tripping, scalable for up to 24 feeders, low-noise numerical operation .
• Hitachi Relion Busbar IEDs: Distributed protection, supports phase-to-phase and phase-to-earth faults, IEC61850 compliant, low-noise digital operation .
• ABB Busbar Protection Relays: Phase-segregated short-circuit protection, suitable for small busbars, low-impedance applications, and residual earth-fault protection . By selecting a numerical low-impedance or high-impedance relay with integrated digital features, Serbian small busbars can achieve reliable protection with minimal operational noise, while maintaining flexibility for future expansion or reconfiguration.