MF790c feeder management relays provide an integrated solution for the complete protection, control and monitoring of overhead lines and underground cables, covering all distribution voltage levels. It has been built with Latest State of art technology that accepts energizing Inputs from Current and Voltage sensors.

Key Benefits

  • Full feeder management with efficient monitoring, control, recording and digital communications

  • Supports major digital control system protocols for integration into DCS, SCADA and engineering workstations.

  • Harsh environment protection extends the life of the product.

  • MF790C with Sensor Offers better accuracy/linearity in measurements over wide range of primary current.

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  • 3-stages of non-directional over current, earth fault, sensitive earth fault protection

  • 2-stages of under voltage, over voltage and residual voltage protection

  • Breaker fail protection, Auto recloser, Sectionalizing & Cold Load Switching Feature/ function.

  • TCS, CB Monitoring/Maintenance, Max Demand Supervision/Control functions.

  • Major power system parameters metering functions.

  • Modbus RTU or IEC60870-5-103/101 with RS 485 Rear Port or IEC60870-5-104 with Ethernet Rear port for Remote Communication.

  • Configurable Outputs, LED’s & Front facia MIMIC with CB status and Live line/Bus Indications

  • Front USB Port for User interface.

Special Application:

  • Auto reclose function offers multi shots reclosing to avoid discontinuity during transient fault tripping in transmission lines.

  • Cold Load Switching feature avoids protection relay tripping due to inrush current, when a distribution circuit is re-energized following an extended outage.

  • The standard curves offers reliable fault tripping, without constraining circuit loadability

  • Cold Load Switching feature avoids protection relay tripping due to inrush current, when a distribution circuit is re-energized following an extended outage.

Device Number Function
79 Auto reclose
86 Latching/Lockout Contacts
50BF CB Failure
CLP Cold Load Pick Up
TCM Trip Circuit Monitor
50N Earth Fault Definitive Time Over current
51N Neutral/Ground IDMT Over current
SEF Sensitive Earth Fault
50 Phase Definitive Time Over current
51 Phase Inverse-Time Over current
59 Phase and Line Overvoltage
27 Phase and Line Undervoltage
59N Residual overvoltage
TRIP / CLOSE breaker control switches with necessary interlock logics with simple MIMIC showing breaker status.
TRIP LOCK facility with password Protection for Line clear / breakermaintenance.
LOCAL / REMOTE switch function with Password Lock.
AUTO Breaker Maintenance annunciation.
Built in ANNUNCIATOR for TRIP and NONTRIP functions with ACCEPT / RESET push buttons and test LED facility.
Built in Trip Circuit Supervision.
Built in breaker ANTIPUMPING logic.
Built in CLOSE / TRIP interlock logics.
DC supply supervision.
34 INDICATING LEDs includes DC healthy, Trip circuit fail, Breaker ON / OFF status, Remote / Local operations, spring charge, Breaker in service status etc., –
14 Digital inputs that includes inputs for Bucholz alarm, Oil temperature alarm , Winding temperature alarm, and Bucholz Trip, Oil temperature Trip, winding temperature Trip functions of Power Transformer.
MASTER TRIP relay function
Device Healthy feature to give alarm with different supply / device failure.
Control button status information in LCD panel.
Dedicated three phase voltage indicator (MVIL3) with LED indicators directly energized from the PT supply, indicating the status of High voltage without depending on dc supply for safety.(optional)
Three Phase & Earth Fault Over current protections With Three stages of settings- Low set, wide set, High set (True RMS measurement).


MF790C PC STUDIO is a PC tool for configuring MF790C Feeder Manager that contains all tools in a palette for simple entry, with intuitive navigation via fewer mouse-clicks.

Key benefits / features in the MB140x PC STUDIO family

  •  Powerful free of charge PC interface tool
  •  Intuitive and versatile interface with file management facilities
  •  Parameterization facilities for IED settings
  •  Real-time measurement visualization
  •  Integrated configuration and monitoring features
  •  Send and extract setting files
  •  Event and disturbance record extraction and analysis