Feeder protection


IRU_PRO is a relay for AC voltage supervision with universal application; it protects the three-phase network against over-, under- voltage, unbalance or earth faults in isolated networks. Beside the pure RMS value measurement of the line voltage the IRU_PRO evaluates the symmetrical components (U1, U2 & U0 sequence system). By evaluating these components relay IRU_PRO can detect the phase sequence, voltage unbalance and earth-faults, Neutral displacement for capacitor protection purpose.

Key Features

» Numeric DSP technology based relay.
» Two Groups of configuration parameter.
» 2 Stage Under & Over voltage Protection.
» Inverse as well as Definite Trip timing curve selection for under/over voltage.
» Separate tripping elements for over- and under voltage and positive sequence system.
» Display of measuring values of the line voltages and system voltages U0, U1 and U2 as RMS values.
» Suitable for Star /Delta connection.
» VT Ratio for Primary Voltage display configuration.
» Block on under voltage in case of Power failure (user selectable).
» Last 10 faults saving in memory for all line voltages and the voltages of the symmetrical components, with time stamp.
» Suitable for 50Hz/ 60Hz.
» Single Phase/ Three Phase selection.
» USB front end interface for PC/Laptop interface.
» Off line Trip Test mode.

 Under Voltage Protection (27)

 Overvoltage Relay(59)

 Neutral Over Voltage / Neutral Displacement (59N)

 Phase-Sequence Voltage Relay(47)

 Positive sequence Over voltage (59D)

Under Voltage Protection IRU PRO – U
Over Voltage Protection IRU PRO – O
Neutral Displacement Protection IRU PRO – R
Under & Over Voltage Protection IRU PRO – UO
Under + Over + Neutral Displacement IRU PRO – UOR

Options : PT input - 110V / 230V / 400V AC


  VT Ratio – 1-1000

  PT input : 110V / 230V / 400V AC

  LCD display of 2 x 16 characters

  To download the last 10 faults of relay

  To download the last 100 Events of relay

  Setting Range: U> : 0.05 to 2.00, Unit : 0.03 - 20 sec, DIFF : 50-100% of Un

  Mounting –Rack or Flush

  Front plate of the unit is protected with a (IP54).


Test Reference Standards
  • Insulation Test
  • Dielectric Test
  • 5 KV impulse voltage Test
  • High freq interference Test severity class 3
  • Radio interference suppression Test
  • Radio interference suppression Test
  • Radiated radio freq electromagnetic field immunity Test
  • Conductive RF immunity Test
  • Surge immunity
  • ESD test severity class 3
  • Fast transient disturbance test
  • Power frequency magnetic Field immunity test
  • IEC 60255-5
  • IEC 60255-5
  • IEC 60255-5
  • IEC 60255-22-1
  • EN55011 cl 5.1.2
  • EN55011 cl 5.22.2
  • IEC 60255-22-3
  • ENV50141
  • EN61000-4-5
  • EN61000-4-2
  • IEC 60255-22-4
  • IEC61000-4-8

  • * External PTV, (on A7 & A8) will be only in
    IRU-PRO-UOR Star Connection in IRU-PRO.

Front View
Side View
Top View