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Products»Smart Line»S24 Series» Variant 2 Dir. 3Ph+Io overcurrent, small generator protection & autorecloser
Variant 2 B&W displayVariant 2 backplaneVariant 1 tft displayS24 Din rail mounting B&W displayS24 Din rail mounting

Similarly to Variant 1, Variant 2 can be used as the main or backup protection of overhead lines and cable networks. Because of its voltage- and frequency-based functions, Variant 2 is recommended especially for applications where small generators are connected to the network / smart grids.

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, Variant 2,…), 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

Variant 2 B&W displayVariant 2 backplaneVariant 1 tft displayS24 Din rail mounting B&W displayS24 Din rail mounting

Variant 2 can be used as the main or backup protection of overhead lines and cable networks. The voltage- and frequency-based functions facilitate the application of the IED for the protection and control of small generators as well. The relay is member of the S24 product type in the EuroProt+ product family.

The Variant 2 relay includes a variety of versatile feeder protection functions based on both current and voltage measurement, such as three-phase, residual and negative sequence overcurrent protection, undercurrent protection, thermal overload protection and directional three-phase and residual overcurrent protection. The voltage- and frequency-based functions can serve as the main protection of small generators. Voltage-dependent overcurrent, vector jump, over- and undervoltage functions as well as over- and underfrequency, frequency change protection, etc. are also available. 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 and directional overcurrent, thermal overload protection functions for overhead lines and cable networks
  •      Over- and undervoltage protection functions
  •      Additional protection and control functions especially for small generators: negative sequence overcurrent, voltage dependent overcurrent, vector jump, frequency-based protection, overexcitation detection
  •      The implemented protection functions provide back-up protection for downstream equipment (e.g. feeders, cables etc.)
  •      Optional restricted earth fault protection function for the simple protection of small transformers
  •      Automatic reclosing function
  •      Breaker failure protection function
  •      Current unbalance detection of CT’s
  •      VT supervision function
  •      Programmable interlocking schemes


Protection & Control functions

The Variant 2 configuration measures the three-phase currents, the residual current component as well as three-phase voltages. These measurements add directionality extension to the configured phase and residual overcurrent functions t  o the current- and voltage-based functions. The frequency is also evaluated (based on the voltage measurement) to realize frequency-based protection functions. It is intended to protect overhead line or cable networks and small generators. The scope of functions is supplemented with the automatic reclosing function. The configuration is designed to meet the requirements of a medium-voltage field unit.

The restricted earth fault protection function is available as an option for small transformer protection.

Protection & control functions IEC ANSI *Inst.
Overexcitation protection function V/Hz 24 1
Definite time undervoltage protection function U<, U<< 27 2
Directional overpower protection function P> 32 1
Directional underpower protection function P< 37 1
Negative sequence overcurrent protection function I2> 46 1
Broken conductor protection I2/I1> 46BC 1
Negative sequence overcurrent protection for generators function I2> 46G 1
Negative sequence definite time overvoltage protection function U2 > 47 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
Voltage dependent overcurrent protection function I> U< 51V 1
Definite time overvoltage protection function U>, U>> 59 2
Residual definite time overvoltage protection function Uo>, Uo>> 59N 2
Voltage transformer supervision and dead line detection function 60 1
Current unbalance function 60 1
Directional three-phase overcurrent protection function I Dir>, I Dir>> 67 2
Directional residual time overcurrent protection function Io Dir>, Io Dir>> 67N/67G 2
Inrush current detection function I2h> 68 1
Automatic reclosing function for medium voltage networks 0 -> 1 79 1
Overfrequency protection function f>, f>> 81O 2
Underfrequency protection function f<, f<< 81U 2
Rate of change of frequency function df/dt 81R 2
Vector jump protection function ΔφU> 78VJ 1
Restricted earth-fault protection function REF 87N 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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