Bay controller

Bay controller - SIPROTEC 6MD85 - side view


Modular bay controller for medium voltage and high to extra-high voltage switchgear with integrated operation and extensive protection functions. Powerful automation, simple configuration with DIGSI 5

Start Configurator for more technical and ordering information.


Bay controller SIPROTEC 6MD85

Features & functions

The SIPROTEC 6MD85 bay controller is a general-purpose control and automation device with protection function. It has been designed for utilization on all voltage levels, from distribution to transmission. As a part of the SIPROTEC 5 family, it allows the use of a large number of protection functions from the SIPROTEC library. The modular hardware permits application-related IOs to be integrated. Adapt the hardware exactly to your requirements and rely on future-oriented solutions for protection, control, automation, monitoring and PQ basic.

Main function: Inputs and outputs

Inputs and outputs:

  • 5 predefined standard variants with 4 current transformers,
    4 voltage transformers,
    11 to 75 binary inputs,
    9 to 41 binary Outputs

Hardware flexibility:

  • Flexibly adjustable and expandable I/O quantity structure within the scope of the SIPROTEC 5 modular system. For great requirements placed on the quantity structure, the device can be extended in the second row. For example, this permits an additional 240 binary inputs (and more) to be used with the IO230 (see chapter "Hardware")

Housing width:

  • 1/3 × 19" to 2/1 × 19"

As standard:


DIGSI 5 permits all functions to be configured and combined as required.

  • Integrated bay controller with versatile protection function from medium to extra-high voltage
  • Control of switching devices
  • Synchrocheck and switchgear interlocking protection
  • Integrated electrical Ethernet RJ45 for DIGSI 5 and IEC 61850 (reporting and GOOSE)
  • Up to 4 pluggable communication modules, usable for different and redundant protocols (IEC 61850-8-1, IEC 61850-9-2 Client, IEC 60870-5-103, IEC 60870-5-104, Modbus TCP, DNP3 serial and TCP, PROFINET IO, PROFINET IO S2 redundancy) 
  • Virtuelle Netzwerkaufteilung (IEEE 802.1Q - VLAN)
  • Redundancy protocols PRP and HSR
  • Arc protection
  • Extensive cybersecurity functionality, such as role-based access control (RBAC), protocolling security-related events, signed firmware or authenticated network access IEEE 802.1X
  • Simple, quick and secure access to the device data via a standard Web browser to display all information and diagnostic data, as well as vector diagrams, single-line and device display pages
  • Graphical logic editor to create powerful automation functions in the device
  • Optional overcurrent protection for all voltage levels with 3- pole tripping
  • Also used in switchgear with breaker-and-a-half configuration
  • Overcurrent protection also configurable as emergency function
  • Selective protection of overhead lines and cables with single-ended and multi-ended feeders using protection communication
  • Secure serial protection data communication, also over great distances and all available physical media (fiber-optic cable, 2-wire connections and communication Networks)
  • PQ-Basic: voltage unbalance; voltage changes: overvoltage, dip, interruption; TDD, THD and Harmonics

  • Capturing operational measured variables and protection function measured values to evaluate the plant state, to support commissioning, and to analyze faults
  • Phasor Measurment Unit (PMU) for synchrophasor measured values and IEEE C37.118 protocol integrated
  • Powerful fault recording (buffer for a max. record time of 80 s at 8 kHz or 320 s at 2 kHz)
  • Point-on-Wave Switching (PoW)
  • Auxiliary functions for simple tests and commissioning
  • Flexibly adjustable I/O quantity structure within the scope of the SIPROTEC 5 modular system



Application templates


The SIPROTEC 6MD85 bay controller is a general-purpose control and automation device with protection function on the basis of the SIPROTEC 5 system.

The standard variants of the SIPROTEC 6MD85 are delivered with instrument transformers. Furthermore, protection-class current transformers are also possible in SIPROTEC 6MD85 so that protection functions can be used. 

Due to its high flexibility, it is suitable as selective protection equipment for overhead lines and cables with single-ended and multi-ended infeed with two ends when protection communication is used. The device supports all SIPROTEC 5 system properties. It enables future-oriented system solutions as well as the acquisition and recording of power quality data in the medium-voltage and subordinate Low voltage network.


Application templates are available in DIGSI for standard applications. They comprise all basic configurations and default settings.


The following application templates are available:



  • Double-busbar feeder with switchgear interlocking

Extended control

  • Additionally to 6MD85 standard, this includes the CFC blocks for switching sequences and arithmetic
  • Switching sequence for automatic busbar transfer preconfigured (started by function key).Switching sequence for automatic busbar transfer preconfigured(started by function key)


  • Safe and reliable automation and control of your systems
  • Purposeful and easy handling of devices and software thanks to a user-friendly design
  • Cybersecurity in accordance with NERC CIP and BDEW Whitepaper requirements
  • Highest availability even under extreme environmental conditions  by “conformal coating“ of printed circuit board assembly

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