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Products»Smart Line»S24 Series» Variant 1 3Ph+Io overcurrent, motor protection & autorecloser
Variant 1 B&W displayVariant 1 backplaneVariant 1 tft displayS24 Din rail mounting B&W displayS24 Din rail mounting

The S24 Variant 1 is used mostly as the main or backup protection of overhead lines, cable networks and motors.

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 customisable.

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

Variant 1 B&W displayVariant 1 backplaneVariant 1 tft displayS24 Din rail mounting B&W displayS24 Din rail mounting

Variant 1
is used mostly as the main or backup protection of overhead lines, cable networks and motors. It is a member of the S24 series, which is part of the EuroProt+ Smart Line.

The Variant 1 relay includes a variety of versatile feeder and motor protection functions such as three-phase, residual and negative sequence overcurrent protection, undercurrent 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.





  •      Three-phase and residual overcurrent protection functions for overhead lines and cable networks
  •      Additional protection and supervision functions for motors: thermal overload, negative sequence overcurrent, undercurrent protection function, start-up supervision function
  •      The implemented protection functions provide back-up protection for downstream equipment (e.g. feeders, cables etc.)
  •      Optional capacitor bank protection functions (capacitor unbalance, capacitor overvoltage)
  •      Automatic reclosing function
  •      Breaker failure protection function
  •      Inrush detection
  •      Current unbalance detection of CT’s
  •      Programmable interlocking schemes
Protection & Control functions

The Variant 1 configuration measures three phase currents and the residual current. The main protection functions are overcurrent functions, the thermal overload function and the undercurrent function. For motor applications, there is a start-up supervision function with restart inhibit. Capacitor protection functions are optional.  The configuration is designed to meet the requirements of a medium-voltage field unit.

Protection & control functions IEC ANSI *Inst.
Loss-of-load (undercurrent) protection function I< 37 1
Negative sequence overcurrent protection function I2> 46 1
Broken conductor protection I2/I1> 46BC 1
Motor startup supervision function Istart/I(t) 48/66 1
Line thermal protection function T > 49 1
Motor thermal protection function T> 49M 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
Capacitor unbalance protection for blocks in double star connection function 51NC op.
Capacitor unbalance protection for blocks in bridge connection function 51NC op.
Capacitor overvoltage protection function 59C op.
*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.
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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