Siemens Siprotec 5 7SS85 Busbar Protection Relay

The SIPROTEC 7SS85 Busbar Protection Relay is a selective, safe, and fast protection against busbar faults 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

• Phase-selective measurement and display
• Selective tripping of faulty bus zones
• Disconnector-independent check zone as additional tripping criterion
• Shortest tripping times (<7 ms) to ensure network stability and minimize damage to the system
• Highest stability in case of external faults, even in case of transformer saturation, through stabilization with flowing currents
• Operate curve with freely adjustable characteristic curve sections
• Additional operate curve with increased sensitivity for low current faults, for example in resistance-grounded power systems
• Fast recognition of internal and external faults re-quires only 2 ms of saturation-free time of the current transformer
• Using closed iron core or linearized current transformers in a plant is possible
• Adaptation of different current transformer ratios per parameterization
• Three interacting methods of measurement allow minimum tripping times after busbar faults and ensure maximum stability in case of large short-circuit currents
• The integrated circuit-breaker failure protection recognizes circuit-breaker faults in the event of a busbar short circuit and provides a trip signal for the circuit breaker at the line end. The adjacent busbar trips if a coupling circuit breaker fails
• There is extensive monitoring of current transformer circuits, measured value acquisition and processing, and trip circuits. This prevents the protection from functioning too tightly or too loosely, which reduces the effort for routine checks
• Various control possibilities, such as bay out of order, acquisition blocking from disconnectors and circuit breakers, blocking of protection zones or circuit-breaker failure protection, make the adaptation to operationally caused special states of your system easier
• Optional 1/3-pole or 3-pole circuit-breaker failure protection using the integrated disconnector image to trip all circuit breakers of the busbar section affected
• Optional end-fault protection for the protection of the section between circuit breaker and current transformer for feeders and bus couplers
• Direct tripping of protection zones through external signals
• Release of the tripping of a protection zone through additional external signals
• Release of tripping through additional, external phase-selective signals
• Optional phase/ground overcurrent protection for each bay
• Optional cross stabilization as additional tripping release in 3-pole encapsulated gas-insulated switch-gear
• Optional bus coupler differential protection for fault clearing in couplers with two current transformers

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.