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Products»Smart Line»S24 Series» Variant 4 MV line differential protection & autorecloser
Variant 4Variant 4 backplaneVariant 4 tft displayS24 Din rail mounting

The S24 Variant 4 is used mostly as the main or backup protection of overhead lines or cable networks. The main protection function of this configuration is the line differential protection.
It is a member of the S24 series, which is part of the EuroProt+ Smart Line. Members of the Smart Line also offer a wide range of functions but they do so in a small, compact enclosure so that they can be installed in locations with limited space available for the protection equipment.

The S24 series contain special selections of the EuroProt+ modules and functions, composed with cost effectiveness in mind. Depending on the standard configuration chosen (Variant 1, Variant2,…), the IED is adapted to the protection of medium-voltage feeders in isolated neutral, resistance earthed, compensated and solidly earthed networks. Once the application-specific settings have been defined for the standard configuration IED, it can be put into service directly. Areas of application include protection functions for a large variety of applications, e.g. transformer differential and restricted earth fault protection, frequency and voltage based protection, motor protection, thermal overload protection.

The EuroCAP configuration tool, which is available free of charge, offers a user-friendly and flexible application for protection, control and measurement functions to ensure that the IED-EP+ S24 devices are fully customizable.

General features

  • Native IEC 61850 IED with Edition 2 compatibility
  • Standard module layouts with options
  • 24 HP wide rack size (height: 3U)
  • The pre-defined factory configuration can be customized to the user’s specification with the powerful EuroCAP tool
  • Different HMI types: advanced HMI with color touchscreen and black-and-white display with 4 tactile push buttons. An embedded web server and extended measuring, control and monitoring functions are also available for both types
  • User configurable LCD user screens for the HMI-type color touchscreen, which can display SLDs (Single Line Diagrams) with switchgear position indication and control as well as measuring values and several types of controllable objects
  • Various protection setting groups
  • Enhanced breaker monitoring and control
  • High capacity disturbance recorder (DRE) and event logging:
    • DRE for up to 32 analogue and 64 digital signal channels
    • Event recorder can store more than 10,000 events
  • Mounting methods: Flush mounting; Semi-flush mounting; Din rail mounting
  • Wide range of communication protocols:
    • Ethernet-based communication: IEC61850; IEC60870-5-104; DNP3.0 TCP; Modbus TCP
    • Serial communication: DNP3.0; IEC60870-5-101/103; MODBUS, SPA
    • Legacy network based protocols via 100Base-FX and 10/100Base-TX (RJ45)
  • Optional communication ports: Fiber optical Ethernet (MM/ST, SM/FC), RJ45, Serial POF, Serial glass fiber, RS-485/422
  • Handling of several communication protocols simultaneously
  • Built-in self-monitoring to detect internal hardware or software errors
  • Different time sources available: NTP server; Minute pulse; Legacy protocol master; IRIG-B000 or IRIG-B12X
Variant 4Variant 4 backplaneVariant 4 tft displayS24 Din rail mounting

Variant 4 is used mostly as the main or backup protection of overhead lines or cable networks. It is a member of the S24 series, which is part of the EuroProt+ Smart Line.

The main protection function of the Variant 4  configuration is the line differential protection. The communication hardware module sends and receives phase current vectors to realize this function. Additionally, the Variant 4 relay includes a variety of versatile feeder protection functions such as three-phase, residual and negative sequence overcurrent protection, thermal overload protection, etc. It can be used as a back-up protection relay for downstream equipment (e.g. feeders, cables). The automatic reclosing function is also part of the standard configuration.

The IED includes a wide range of control and supervisory functions, which provide full control and user-defined interlocking schemes for the primary switchgear at the substation.


  •      Line differential protection function
  •      Length of the protected line up to 50km with single-mode fiber optic cable; short lines up to 1 km with mono-mode fiber optic cable port are also supported
  •      Three-phase, residual and negative sequence overcurrent, thermal overload protection functions
  •      The implemented protection functions provide back-up protection for downstream equipment (e.g. feeders, cables etc.)
  •      Automatic reclosing function
  •      Breaker failure protection function
  •      Inrush detection
  •      Current unbalance detection of CT’s
  •      Programmable interlocking schemes


Protection & Control functions

The Variant 4 configuration measures the three phase currents and the residual current. The main protection function in this application is the line differential protection function. Additionally, overcurrent functions and the thermal overload function are also available for protection of overhead lines and cable networks.  The configuration is designed to meet the protection requirements of a medium-voltage field unit.

Protection & control functions IEC ANSI *Inst.
Negative sequence overcurrent protection function I2> 46 1
Broken conductor protection I2/I1> 46BC 1
Line thermal protection function T > 49 1
Three-phase instantaneous overcurrent protection function I >>> 50 1
Residual instantaneous overcurrent protection function Io>>> 50N/50G 1
Breaker failure protection functions CBFP 50BF 1
Three-phase time overcurrent protection function I>, I>> 51 2
Residual overcurrent protection function Io>, Io>> 51N/51G 2
Current unbalance function 60 1
Inrush current detection function I2h> 68 1
Automatic reclosing function for medium voltage networks 0 -> 1 79 1
Line differential protection function 3IdL > 87L 1
*The INST. column contains the numbers of the pre-configured function blocks in the factory configuration.These numbers may be different in order to meet the user’s requirements.
Brochures version Format Date Size
EuroProt+ overview 1.1 19/02/2021 1.08 MB
System Description version Format Date Size
IED-EP+ S24 general specification 2.0 19/02/2021 1.24 MB
Hardware Guides version Format Date Size
Maintenance guide 2.0 18/11/2022 769.82 KB
Hardware description 2.00 10/02/2023
4.24 MB
Application Guides version Format Date Size
Line differential communication application guide 1.4 29/11/2019 0.99 MB
IEC61850 documents version Format Date Size
Protocol Implementation Extra Information - PIXIT 1.1 20/03/2017 259.27 KB
Protocol Implementation Conformance Statement - PICS 1.1 20/03/2017 261.09 KB
Model Implementation Conformance Statement - MICS 1.0 21/05/2012 864.71 KB
Configuration Descriptions version Format Date Size
Variant 4 configuration description 2.2 26/01/2015 4.40 MB
Variant 4 product configuration options 3.2 25/08/2022 -
Protecta products can be ordered by using an Order Code. This code specifies the hardware and the configuration.
Please always refer to a valid Order Code when placing an order.
The Order Code page can be opened by clicking the link below.
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