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

Beckwith Electric's Transformer Protection System M-3311A provides protection, control, monitoring and user interface functions for two, three or four-winding transformers. The system 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 and 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 M-3826 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.

Generator-Transformer Unit Overall Differential
Unit Protection of Other Electrical Apparatus and certain Bus
Arrangements (including those with a transformer in the zone)
Additional Applications: System Backup Protection, Load Shedding
(voltage and frequency), Bus Protection, and individual Breaker Failure
Protection for each winding input
Options: Ethernet Connection and Expanded I/O

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)
IPSlogicTM

Optional Single-Phase Voltage Protection Package

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

Standard Features

Eight programmable outputs and six programmable inputs
Oscillographic recording
Through-Fault Monitoring
10-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
M-3826 IPScom® Communications Software
IRIG-B time synchronization
Breaker Monitoring
Multiple Setpoint Groups
Trip Circuit Monitoring
Includes MODBUS and DNP 3.0 protocols
Summing Currents from mulitple sources for 49, 50, 51, 50N, 51N, 87 GD and Through Fault functions