The ultimate busbar protection

Busbar protection – SIPROTEC 7SS85


The SIPROTEC 7SS85 busbar protection is a selective, safe and fast protection against busbar short circuits in medium, high, and very high voltage systems.

Busbar protection SIPROTEC 7SS85

Features & functions

The proven, fast and safe algorithms from SIPROTEC 7SS52 in connection with the flexible, scalable, open and user-friendly SIPROTEC 5 platform set the new standard for busbar protection SIPROTEC 7SS85.


SIPROTEC 5 busbar protection - the best solution for all customer requirements wherever energy flows.
The proven, fast and secure algorithms of SIPROTEC 7SS52 combined with the flexible, scalable, open and user-friendly SIPROTEC 5 platform gave birth to the new benchmark of busbar protection: SIPROTEC 7SS85.

If you  are looking for a successor of the SIPROTEC 7SS52, IEC 61850 interoperable and open solution in line with your digital substation strategy and cost-efficient enhancement of your grid resilience with busbar protection, the SIPROTEC 7SS85 is the right solution for you.


ONE platform, ONE device, ONE configuration tool for all your applications, voltage levels and busbar protection schemes:  The new SIPROTEC 7SS85 offers different busbar protection  possibilities and for the first time in history, a hybrid busbar protection scheme where the same device SIPROTEC 7SS85 will collect process information directly connected and through distributed bay units.


Did you know? You can do all configurations, expansions, and adaptations of SIPROTEC busbar protection on your own!

IEC 61850 compatible and interoperable busbar protection with decentralized process interconnection

IEC 61850 compatibility and interoperability are key criteria for your protection and energy automation system: Communication between SIPROTEC 7SS85 central unit and the bay units is based on the latest IEC 61850 standards (IEC 61850-9-2 for SMV and IEC 61850-8-1 MMS and GOOSE). This ensures that the busbar protection is seamlessly integrated in the overall digital substation architecture.


Our unique proposal for you:

With SIPROTEC 7SS85 you can realize interoperable digital substations with distributed busbar protection fully integrated in the overall IEC 61850 process and station bus system architecture. The interoperability , ensured by the IEC 61850 standard, offers the possibility to use any compliant merging unit or protection device as bay unit.

Cost-efficient enhancement of your grid with busbar protection

Enhance the resilience and reliability of your distribution, industry or infrastructure grid with our cost-efficient busbar protection SIPROTEC 7SS85. With its unique design based on the SIPROTEC 5 platform, the SIPROTEC 7SS85 enables a versatile and seamless integration into the SIPROTEC 5 protection schemes.  It can collect process information from any SIPROTEC 5 modular device and use it to perform the busbar protection algorithms.


Our unique proposal for you:

The modular SIPROTEC 5 relays fulfil two purposes at the same time: as protection relay to protect the respective feeder and as bay units of the busbar protection system. By doing so, you add reliability and security to your system with minimum investments and space requirements. In case of future expansion of your substation, you can seamlessly integrate the new feeder into the busbar protection by choosing the bay unit which fits your needs in terms of hardware and protection features.

Successor of SIPROTEC 7SS52 

You are looking for a successor of SIPROTEC 7SS52 bus bar protection: With SIPROTEC 7SS85 you can benefit from the combination of advantages from SIPROTEC 7SS52 and the SIPROTEC 5 platform.

SIPROTEC 7SS85 is using the well-proven, fast and secure SIPROTEC 7SS52 algorithms which have been protecting hundreds of substations all over the world with the highest level of reliability for more than 30 years.

The SIPROTEC 5 platform adds several advantages: hardware and software modularity, flexibility, embedded cybersecurity, user-friendly interface and enhanced communication capabilities.



Our unique proposal for you:

With SIPROTEC 7SS85 you can easily retrofit your SIPROTEC 7SS52 busbar protection system, by using the same know-how and keeping the philosophy and the safety through functions which are already proven and established in your substations.

Additionally, you benefit from the flexibility of SIPROTEC 7SS85 to choose the bay unit which fits your needs in terms of hardware and protection functions:

  • Using SIPROTEC 6MU85 as a standalone bay unit or using any SIPROTEC 5 modular protection device as a bay unit of the distributed busbar protection.
  • To increase the reliability of your system, we are offering optional redundant communication between the central unit and the bay units.


The SIPROTEC 7SS85 busbar protection is the solution for the following system configurations:

  • Single to five-way busbars with/without transfer busbar

  • Breaker-and-a-half layout method

  • Dual circuit-breaker systems and one or two current transformer(s) per feeder

  • Truck-Type Switchgear

  • combined busbar systems (alternatively main/transfer busbar)

  • H connection arrangement with busbar coupler or disconnection

  • Ring busbars


The busbar protection SIPROTEC 7SS85 encompasses the following maximum quantity structures


All functions can be configured as required with DIGSI 5. Using some functions requires the appropriate number of free function points to be available in the device. The function point calculator in the online configurator provides support in the determination of the required number of function points for your device. The necessary function points are also shown during project engineering with DIGSI 5.


Characteristic Key Values of SIPROTEC 7SS85

  • Phase-selective measurement and display

  • Selective tripping of faulty bus zones

  • Disconnector-independent check zone as additional tripping criterion

  • Shortest tripping times to ensure network stability and minimize damage to the system

    - Central busbar protection: 3 ms/7ms (Relais Typ HS/Typ F)

    - Decentral busbar protection: 8 ms/12 ms (Relais Typ HS/Typ F)

  • 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 errors, for example in resistance-grounded 
    power systems

  • Fast recognition of internal and external errors requires 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

  • Straight-forward dimensioning of current transformers and stabilization factor

  • 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 subfunction, 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 plant easier

  • 1/3-pole or 3-pole circuit-breaker failure protection using the integrated disconnector image for tripping 
    all circuit breakers of the busbar section affected

  • 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

  • Cross stabilization against overfunctions in case of transformer influence on the secondary side

  • Bus coupler differential protection for fault clearing in couplers with two current transformers.
  • With decentralized busbar protection, any feeder protection function can be additionally implemented by using any modular SIPROTEC 5 device as a bay device.
  • Extensive cyber security functionality, such as role-based access control (RBAC), protocolling security-related events, signed firmware or authenticated network access IEEE 802.1X


Function library and application templates

The flexibility of the SIPROTEC 7SS85 allows for the protection of a large number of possible system configurations. In place of application templates, DIGSI 5 makes a comfortable, fully graphical interface for complete engineering of your busbar protection available.


Integrate your existing SIPROTEC 5 feeder protection devices as bay units of the distributed busbar protection SIPROTEC 7SS85 - based on IEC 61850-9-2 process bus.

Add SIPROTEC 5 merging units 6MU85 to new substation feeders and expand your SIPROTEC 7SS85 busbar protection system.

Benefits of distributed busbar process bus solution

  • Compatible with all relevant process bus standards such as IEC 61850-9-2 and IEC 61869-9
  • Sample and date/time synchronization via IEEE 1588v2/PTP
  • Existing SIPROTEC 5 feeder protection devices can be used as bay units
  • SIPROTEC 5 merging units digitalize the measured values directly at the process
  • Back-up protection functions integrated in the SIPROTEC 5 merging units offer additional system security
  • During commissioning all settings can be done with DIGSI 5 and the IEC 61850 system configurator directly via process bus network.
  • Interoperability with multivendor merging units (IEC 61850 Edition 2.1 compliance recommended)


  • Fast and secure – Proven and reliable algorithms since 1989
  • Cyber Secure – Compliant with NERC CIP and BDEW Whitepaper-Requirements
  • Robust – Highest availability even under extreme environmental influences
  • Consistent – One platform, one device, one configuration tool

  • User-friendly – Configuration by the user during the entire service life
  • Clearly structured – Full graphical engineering and online plant visualization with DIGSI 5
  • Flexibility – Centralized, decentralized or combined (hybrid) Architecture
  • Universal – SIPROTEC 5 protection devices and merging units as bay unit
  • Powerful – Busbar protection device as central feeder protection
  • Economical – Extension of the protection system with busbar protection
  • Interoperable – Compatible with Merging Units according to IEC 61850 Rev.2.1

The performance and flexibility of the SIPROTEC 7SS85 allow the implementation of a wide range of customer-specific secondary technology concepts and solutions, such as:

  • IEC 61850 compatible and interoperable distributed busbar protection
  • Cost-efficient extension of the protection system with busbar protection
  • Successor solution for the power-proven SIPROTEC 7SS52



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