Siemens Siprotec 5 7SS85 Busbar Protection Relay

The SIPROTEC 7SS85 Busbar Protection Relay is a selective, safe, and fast protection against busbar faults. Specifically, in medium voltage, high-voltage, and very high voltage systems with the most various busbar configurations. Busbar protection devices SIPROTEC 7SS85 are part of the modular SIPROTEC 5 series and their main function bases on the principle of differential protection. Additional protection and control functions extend the scope of application to a comprehensive station protection.

The flexibility of the functions and the modular hardware structure allow an optimum adaptation of the 7SS85 to the most various system configurations and functional requirements.FunctionalityThe centralized busbar protection SIPROTEC 7SS85 encompasses the following maximum quantity structure:-20 3-phase measuring points (current transformer)-4 3phase measuring points (voltage transformer)-26 bays (feeders, couplers, bus-section disconnections)-4 bus zones (busbar sections with measuring function)-4 couplers (with 1 or 2 current transformers)-2 auxiliary busbars (busbar sections without measuring function)-Phase-selective measurement and Display-Selective tripping of faulty busbar sections.-Optional additional decentralized binary in- and outputs via protection interface (PI) or IEC 61850 (GOOSE) provide new concepts for busbar protection

Characteristics of the SIPROTEC 7SS85

• Supports phase-selective measurement and display for accurate monitoring of busbar conditions.

• Enables selective tripping of faulty bus zones, ensuring quick isolation of faults.

• Includes a disconnector-independent check zone that acts as an additional tripping criterion.

• Provides very fast tripping times (<7 ms) to maintain network stability and reduce equipment damage.

• Maintains high stability during external faults, even with transformer saturation, through stabilization with flowing currents.

• Uses an adjustable operate curve with configurable characteristic sections.

• Offers an additional high-sensitivity operate curve for detecting low-current faults in systems such as resistance-grounded networks.

• Recognizes internal and external faults within 2 ms, requiring only a short saturation-free period from the current transformer.

• Works with closed iron-core or linearized current transformers, providing flexibility in plant design.

• Allows adaptation of different current transformer ratios through parameterization.

• Uses three coordinated measurement methods to achieve fast fault clearing while maintaining stability during large short-circuit currents.

• Includes integrated circuit-breaker failure protection, which detects breaker faults during busbar short circuits and sends a trip signal to the line-end breaker.

• Trips the adjacent busbar automatically if a coupling circuit breaker fails.

• Provides comprehensive monitoring of current transformer circuits, measurement processing, and trip circuits to improve protection reliability.

• Reduces maintenance effort by preventing overly sensitive or insufficient protection settings.

• Offers multiple control options, such as bay-out-of-service status, acquisition blocking from disconnectors and circuit breakers, and protection zone blocking.

• Supports optional 1-pole or 3-pole circuit-breaker failure protection using the integrated disconnector image.

• Provides optional end-fault protection for sections between circuit breakers and current transformers.

• Allows direct tripping of protection zones through external signals.

• Supports additional external signals for tripping release and phase-selective tripping.

• Includes optional phase and ground overcurrent protection for each bay.

• Offers optional cross stabilization for gas-insulated switchgear applications.

SIPROTEC 7SS85 Busbar Protection Relay

SIPROTEC 5 is part of the new generation of incomparable modular, flexible, and intelligent digital field devices. With modularly designed hardware and software and its high-performance DIGSI 5 engineering tool, the SIPROTEC 5 product family of field devices are perfect for protection, control, monitoring, and measuring applications in electrical energy systems. SIPROTEC 5 offers a wide product range with modular elements for every application and requirement.