SE-701 Series

Ground-Fault Monitor

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The SE-701 is a microprocessor-based ground-fault relay for resistanceand solidly-grounded systems. In addition to common systems, it is uniquely suited for use on systems with significant harmonic content. The SE-701 can provide main-plant protection, feeder-level protection, or individual-load protection. Proper current transformer selection provides the desired pickup range. The output contacts can be connected for use in protective tripping circuits or in alarm indication circuits. The analog output can be used with a PLC or a meter.

Features & Benefits

  • Adjustable pickup (1-99%)

    Trip setting based on input CT primary, allows use with any CT. Minimum 50 mA with EFCT Series

  • Adjustable time delay (50 ms-2.5 s)

    Adjustable trip delay allows quick protection and system coordination
  • Output contacts

    Form A and Form B ground-fault output contacts for operation of separate annunciation and trip circuits

  • Analog output (0-5 V)

    Allows for connecting an optional meter (PGA-0500) or a control system

  • CT-Loop monitoring

    Alarms when CT is not connected

  • Selectable DFT or peak detection filtering

    Compatible with variable-speed drives

  • Harmonic filtering

    Eliminates nuisance tripping

  • Non-volatile trip memory

    Retains trip state while de-energized to simplify troubleshooting

  • Microprocessor based

    No calibration required, saves on maintenance cost

  • Universal power supply

    Allows operation in application where one side of PT is faulted, provides flexibility for numerous applications

SE-701 Datasheet

SE-701 Manual

SE-701, 703, 704 3D Model

Littelfuse Protection Relays Lowering the Limits TN

TN CT-01 Ground Fault CT Selection Guide


  • IEEE Device Numbers: Ground fault (50G/N, 51G/N)
  • Input Voltage: See ordering information
  • Dimensions: H 75 mm (3.0"); W 55 mm (2.2"); D 115 mm (4.5")
  • Trip Level Settings: 1-99% CT-Primary Rating
  • Trip Time Settings: 0.05-2.5 s
  • Contact Operating Mode: Selectable fail-safe or non-fail-safe
  • Harmonic Filtering: Standard feature
  • Test Button: Standard feature
  • Reset Button: Standard feature
  • CT-Loop Monitoring: Standard feature
  • Output Contacts: Isolated Form A and Form B
  • Approvals: CSA certified, UL Listed (E340889), CE (European Union), C-Tick (Australian)
  • Analog Output: 0-5 V
  • Conformally coated: Consult factory
  • Warranty: 5 years
  • Mounting: DIN, Surface (standard) Panel (with PMA-55 or PMA-60 adapter) 

Ordering Information

SE-701-OU 120/240
SE-701-OD 12/24
SE-701-OT 48
SE-701-O3 24

Current Transformer
PMA-55, PMA-60
SE-EFVC Voltage Clamp


Ground-Fault Current Transformer
Required current transformer model depends on application. We offer a variety of sensitive CTs with 5- and 30-A primaries.

PGA-0500 Analog % Current Meter
Optional panel-mounted analog meter displays ground-fault current as a percentage of the CT primary rating.