M-3425A Comprehensive Generator Relay
Integrated Protection System for Generators of All Sizes

The M-3425A Comprehensive Generator Relay provides protection, control, monitoring and user interface functions for generator protection. Stored targets and oscillography can be IRIG-B synchronized. Dual RS-232 ports and an RS-485 port provide user-interface communication capabilities. The S-3400 IPScom Communications Software is included for direct serial or remote communication access. Waveform data can be downloaded using the M-3801D IPSplot PLUS Oscillograph Analysis Software which allows for plotting and printing of the downloaded oscillographic data.

  • Exceeds IEEE C37.102 and Standard 242 requirements for generator protection

  • Protects generators of any prime mover, grounding and connection type

  • Provides all major protective functions for generator protection including:
    • Out-of-Step (78)
    • Split-Phase Differential (50DT)
    • Under Frequency Time Accumulation (81A)
    • Inadvertent Energizing (50/27)
    • Turn-to-Turn Fault (59X)

  • Expanded IPScom® Communications Software provides simple and logical setting and programming, including logic schemes

  • Simple application with Base and Comprehensive protection packages

  • Load encroachment blinders and power swing blocking for system backup protection (21) to enhance security during system abnormal conditions

  • Options:
    • Ethernet Connection
    • Field Ground/Brush Lift-Off Protection (64F/B)
    • 100% Stator Ground Fault Protection by low frequency injection (64S)
    • Expanded I/O (15 additional Output Contacts and 8 additional Control/Status Inputs)

  • Configuration Options:

    The M-3425A Generator Protection Relay is available in either a Base or Comprehensive package of protective functions. This provides the user with flexibility in selecting a protective system to best suit the application. Additional Optional Protective Functions may be added at the time of purchase at per-function pricing. The Human-Machine Interface (HMI) Module, Target Module, or redundant power supply can be selected at time of purchase. When the Field Ground (64F) Premium Protective Function is purchased, an external coupler module (M-3921) is provided for isolation from the dc field voltages. When 100% Stator Ground (64S) protection using low-frequency injection is purchased, an external band pass filter and frequency generator is provided.

Protective Functions: Base Package

Function #

24 Overexcitation (V/Hz)

27 Phase Undervoltage

32 Directional power sensitive triple-setpoint Reverse Power, Low Forward Power or Overpower detection, one of which can be used for sequential tripping

40 Dual-zone, offset-mho Loss of Field, which may be applied with undervoltage controlled accelerated tripping

46 Sensitive Negative Sequence Overcurrent protection and alarm

50 Instantaneous Phase Overcurrent

50/27 Inadvertent Energizing

50BF Generator Breaker Failure

50N Instantaneous Neutral Overcurrent

51N Inverse Time Neutral Overcurrent

51V Three-phase Inverse Time Overcurrent with voltage control and voltage restraint.

59 Phase Overvoltage

59N Neutral Overvoltage

59X Multi-purpose Overvoltage

60FL VT Fuse-Loss Detection and blocking

67N Residual Directional Overcurrent

81 Four-step Over/Underfrequency

87 Phase Differential Current

87GD Ground (zero sequence) Differential Current

Protective Functions: Comprehensive Package
Includes all Base Package functions, as well as the following:

Function #

21 Three-zone Phase Distance protection for phase fault backup protection

27TN 100% Stator Ground Fault protection using Third Harmonic Neutral Undervoltage

49 Winding thermal protection

59D Third Harmonic Voltage Differential (ratio)

50DT Definite time overcurrent for split-phase differential

78 Out-of-step (Mho Characteristic) protection

81A Underfrequency Accumulation

81R Generator Breaker Failure

Protective Functions: Optional

Function #

25 Sync Check with Phase Angle, ΔV and ΔF with dead line/dead bus options

64F Field Ground

64B Brush Lift Off

64S 100% Stator Ground Fault by 20Hz Injection

The following equipment is required with the 64S option:
  • 20 Hz signal generator (430-00426)
  • Band-pass Filter (430-00427)
  • 400/5 A 20 Hz CT (430-00428)

Sales and Service