IOMod FPI – Fault passage indicator


IOMod FPI is a fault passage indicator module for medium voltage applications that can be used as a standalone device or part of Elseta mini RTU with voltages and currents based on sensors technology or with adapters connected to current and voltage transformers with communication support based on Modbus RTU, IEC 60870-5-101, and IEC 60870-5-103 protocols.

Designed for short-circuit and earth fault indication with direction detection. IOMod FPI can be used for numerous applications like electrical distribution substations, photovoltaic and hydropower plants, and railway power supplies where the user needs them.

IOMod FPI also calculates neutral current and voltage RMS values I0 and U0 as well as many other measurements like active, reactive, apparent power for every phase, power factors per phase, phase angles for currents and voltages, and more.

Unique by the device size and functionality complexity, it perfectly fits into any application like a recloser, RTU cabinet, or switchgear retrofit project. This device enables utilities and distribution network operators (DNO) to digitalize substations into smart grid elements.


  • Directional fault detection for all network types;
  • Earth fault detection;
  • 50 Instantaneous overcurrent detection;
  • 50N Neutral instantaneous overcurrent detection;
  • 51/67 Phase directional overcurrent detection;
  • 67N Neutral directional overcurrent detection;
  • 27 Under voltage detection (with VT or voltage sensors);
  • 59 Over voltage detection (with VT or voltage sensors);
  • 59N Neutral over voltage detection / permanent earth fault (with VT or voltage sensors);
  • 81HBL2 Inrush blocking for selected protections;
  • 2 settings groups;
  • integration into Elseta mini RTU;
  • Measurements of RMS values for currents, phase, and phase-to-phase voltages.
  • Additional measurements of:
    • Frequency;
    • Active, reactive, and apparent power;
    • Neutral voltage, neutral current;
    • Power factor;
    • Phase angle;
    • Total Harmonics distortion;
  • Analog inputs measurement in 16-bit resolution
  • 3x low-power (LoPo) current measuring inputs (225 mV) or 3x1A/5A CT with the adapter.
  • 3x low-power (LoPo) voltage measuring inputs (3.25 V/√3) or 3x100V/400V VT with the adapter.
  • Frequency acquisition (nominal frequency 45 to 65 Hz).
  • Communication port: RS485
  • Communication over Modbus RTU, IEC 60870-5-101, and IEC 60870-5-103 protocols.


Device data
Article numberIOMOD-FPI
Product Description3 Current sensor inputs and 3 Voltage sensor inputs module
Configuration softwareIOMOD Utility, Serial console (putty)*
Warranty2 years
Measurement values and functions
Analog inputs6x 16-bit resolution
Input typesChannel-independent
Current inputs3
Current inputs measurement range225 mV (IEC 61869-10) with external adapter 1A / 5A
Current input impedance1 MΩ; < 170 pF
Voltage inputs3
Voltage input measurement range3.25 V/√3 AC (IEC 61869-11) with external adapter 100VAC / 400VAC
Voltage input impedance1 MΩ; < 170 pF
Frequency measurement range45..65 Hz
Overvoltage protection±20V
Interface and communication
RS485 interfaceANSI/TIA/EIA-485-A-1998
Communication protocols– Modbus RTU Slave;
– IEC 60870-5-101 Slave;
– IEC 60870-5-103 Slave.
Baudrate600 – 115200 baud
ParityNone, Even, Odd
Terminating resistors120 Ohm (configurable)
USB interface
TypeMini USB
UseConfiguration/Firmware upgrade
Power supply
Auxiliary power supply9-33VDC (full range)
Power consumption40mA @ 12VDC, 20mA @ 24 VDC
Insulation voltage3 kV
Operating conditions
Operating temperature-40°C … 85°C
Storage temperature-40°C … 85°C
Humiditymax. 95 % (non-condensing)
Protection classIP20
Dimensions and installation instructions
Case height x width x depth119 x 17.5 x 101 mm
Installation typeDIN Rail mounting
* IOMOD Utility is configuration tool for IOMOD devices with firmware v2.x, for devices with fw v1.x configuration can be done via USB port as Serial console interface like Putty.



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IOMOD-FPI-RJ – 3xCurrent 3xVoltage sensors module with 2xRJ45 connectors and IEC-101, IEC103, Modbus-RTU protocol support.

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