GE Multilin 745 Draw out Transformer Protection


High-speed, draw-out transformer protection and management

The 745 Transformer Protection System is a full featured transformer protection relay, suitable for application on small, medium, and large power transformers. The 745 can be applied on two-winding and three-winding transformers. Uses multiple current and voltage inputs to provide primary protection and back-up protection of transformers, including differential, ground differential phase, neutral, and ground overcurrent, over-fluxing, and on-load tap changer.

Key Benefits:

  • Easy to use Transformer Protection supported by industry leading suite of software tools
  • Improved security for transformer energization
  • Accurate built-in metering functions
  • Advanced FlexLogic automation capabilities
  • Fast, flexible and reliable communications
  • IRIG-B time synchronization, event reports, waveform capture, data logger
  • Built in simulation features for setpoint verification
  • Modbus and DNP 3.0 Level 2 protocols through embedded Ethernet, standard RS232, RS485 & RS422 serial ports.
  • Optional conformal coating for chemically corrosive and humid environments
  • Security Audit Trail provides detailed traceability for system configuration changes
  • Minimize maintenance time with draw-out capability
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Key Benefits

      • Variable dual-slope percent differential protection
      • Magnetizing inrush and overexcitation blocking
      • Phase & ground overcurrent elements
      • Adaptive time overcurrent using FlexCurves elements
      • Underfrequency/Overfrequency Protection
      • Frequency rate-of-change Detection
      • Overexcitation (V/Hz) Protection
      • Restricted Ground Fault Protection
      • Transformer overload protection
      • Metering – current, voltage, sequence components per winding, power, energy, voltage
      • THD and harmonics up to the 21st
      • Expanded (doubled) sequence of event recorder and waveform capture (256 time stamped events and
        up to 128 cycles of oscillography data at a sampling rate of 64 samples per power cycle)
      • Tap position up to 50 tap positions
      • Ambient temperature /analog transducer input
      • Analog transducer input
      • Oscillography & Data Logger – 10 records up to 32 power cycles
      • Simulation mode and playback capability.



      • Primary and back-up protection and management of small, medium and larger power transformers, autotransformers and reactors
      • Transformer asset monitoring using Hottest Spot, Loss-of-Life and Ageing Factor
      • Stand-alone or component in automated substation control system


The 745 is equipped with three standard serial communications ports, one RS232 located in the front panel, and two RS485/RS422 in the rear of the relay. One optional Ethernet port is available at the rear of the relay. The front panel port allows easy local computer access. The rear ports provide remote communications or connection to a DCS, SCADA, or PLC. The baud rate of all the ports is variable from 300 to 19,200 bps. The optional Ethernet port can be used to connect the 745 to 10 Mbps Ethernet networks. The 745 supports ModBus® RTU, DNP3.0 Level 2, and ModBus® RTU TCP/IP protocols.The three serial ports support ModBus® RTU protocol, while either of the two rear ports can be configured to support DNP 3.0 Level 2. The optional Ethernet port supports ModBus® RTU via TCP/IP protocol. The communication system of the 745 is designed to allow simultaneous communication via all ports.Using Ethernet as the physical media to integrate the 745 to Local or Wide Area Networks, replaces a multidrop-wired network (e.g., serial Modbus®), and eliminates expensive leased or dial-up connections, reducing monthly operating costs.


User Interface:

Various user interfaces facilitate operation of the 745


A 40 character display allows access to setpoints, actual values, and diagnostic messages generated by a trip or alarm condition. The 745 can display 30 user-selected messages during keypad inactivity.


Twenty LEDs indicate relay status, system status, and trip and alarm conditions.

IRIG-B Input

This feature provides time synchronization via standard GPS clock inputs.


EnerVista Software:

The EnerVista™ Suite is an industry-leading set of software programs that simplifies every aspect of using the 745 relay. The EnerVista™ suite provides all the tools to monitor the status of the transformer, maintain the relay, and integrate information measured by the 745 into DCS or SCADA monitoring systems. Convenient COMTRADE and Sequence of Events viewers are an integral part of the 745 Setup software included with every 745 relay, to carry out postmortem event analysis to ensure proper protection system operation.

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