Tel: +1 315 673 1797  
Electrical Products, Inc
Home About Us Products Contact Us

M-3311A Transformer Protection

Two, Three or Four Winding Protection for Transformers of All Sizes


The M-3311A Transformer Protection System provides protection, control, monitoring and user interface functions for two, three or four-winding transformers. Includes restrained and unrestrained differential protection, overcurrent protection, and optional voltage, and underfrequency protection. Multiple setpoint groups and user-implementable logic schemes provide flexibility. Dual RS-232 ports and an RS-485 port provide user-interface capabilities. Optional modules include the HMI Module for front-panel operation, the Target Module to indicate trip target status and redundant power supply. The M-3311A can be purchased as a differential and overcurrent relay or with the Optional Voltage Protection Package. The IPScom® Communications Software is included for direct serial or remote communication access. Waveform data can be downloaded using IPScom®, while the M-3801D IPSplot® PLUS Oscillographic Analysis Software allows for plotting and printing of the downloaded oscillographic data.

Protective Functions: Base Package

Function #

46 Negative Sequence Overcurrent

49 Winding Thermal Protection

50 Instantaneous Phase Overcurrent

50BF Breaker Failure

50G Instantaneous Ground Overcurrent

50N Instantaneous Residual Overcurrent

51 Inverse Time Phase Overcurrent

51G Inverse Time Ground Overcurrent

51N Inverse Time Residual Overcurrent

87 Phase Differential Current

87GD Ground Differential

IPS IPSlogic

TCM Trip (Aux Input) Circuit Monitor

BM Breaker Monitoring

TF Through Fault

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

Function #

24 Volts/Hz Overexcitation

27 Phase Undervoltage

59 Phase Overvoltage

59G Ground Overvoltage

81O/U Overfrequency/Underfrequency

TCM Trip and Close Circuit Monitor (Expanded I/O Units)

CCM Close Circuit Monitor

Standard Protective Functions

  • Negative-sequence inverse time overcurrent (46)
  • Winding thermal protection (49)
  • Four winding instantaneous phase overcurrent (50)
  • Breaker Failure (50BF)
  • Instantaneous ground overcurrent (50G)
  • Instantaneous residual overcurrent (50N)
  • Four winding inverse time phase overcurrent (51)
  • Inverse time ground overcurrent (51G)
  • Inverse time residual overcurrent (51N)
  • Two, three or four winding phase differential (87T) and high set instantaneous (87H)
  • Ground differential (87GD)
  • IPSlogic®

Optional Voltage Protection Package

  • Overexcitation (24) V/Hz, two definite time and one inverse time elements
  • Phase Undervoltage (27) function for load shedding
  • Phase Overvoltage (59)
  • Ground Overvoltage (59G)
  • Over/Underfrequency (81O/U)

Standard Features

  • Eight programmable outputs and six programmable inputs
  • Oscillographic recording
  • Through-Fault Monitoring
  • 8-target storage
  • Real time metering of measured and calculated parameters, including demand currents
  • Two RS-232 and one RS-485 communications ports
  • Standard 19" rack-mount design
  • Removable printed circuit board and power supply
  • 50 and 60 Hz models available
  • 1 or 5 A rated CT inputs available
  • IPScom® Communications Software
  • IRIG-B time synchronization
  • Sequence of Events Log
  • Breaker Monitoring
  • Multiple Setpoint Groups
  • Trip Circuit Monitoring
  • Includes MODBUS and DNP 3.0 protocols
  • Summing Currents from multiple sources for 49, 50, 51, 50N, 51N, 87 GD and Through Fault functions

Optional Features

  • Redundant Power Supply
  • M-3911A Target Module
  • M-3931 Human-Machine Interface (HMI) Module
  • M-3801D IPSplot® Plus Oscillograph Analysis Software
  • RJ45 Ethernet port utilizing MODBUS over TCP/IP, BECO 2200 over TCP/IP, IEC 61850 or DNP 3.0 protocol
  • Expanded I/O (8 additional outputs and 12 additional inputs)
  • Standard and Expanded I/O Models available in vertical panel mount
  • Close Circuit Monitoring on Expanded I/O units











CopyRight @ 2009 EPI . All right reserved.

Privacy Policy

Legal Information
4327 Kencrest Drive, Syracuse, NY, 13215
Tel: 315-673-1797
Fax: 315-673-1797