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Multilin 339

Motor protection systems

The Multilin™ 339 is a member of the Multilin 3 Series protective relay platform and has been designed for the protection, control and management of medium voltage motors in industrial applications. The Multilin 339 delivers unparalleled protection, control, diagnostics and communications in an industry leading drawout construction. Providing simplified setup configuration through the use of the Motor Settings Auto-Configuration, advanced graphical diagnostics with the Motor Health Report and support for multiple communication protocols including IEC® 61850, the 339 Motor Protection System provides comprehensive motor protection for most small and medium sized motors.

Key Benefits

  • Cost-effective and flexible protection and control device for motors

  • Field-proven algorithms and reliable protection to avoid unwanted trips or under-protection

  • Ease of use and standardization with simplified motor setup and universal CT inputs

  • Enhanced Thermal Model including RTD and current unbalance biasing

  • Environmental monitoring system to monitor operating conditions and plan preventative maintenance

  • Time stamped event reports, waveform capture, motor start and motor trending

  • Powerful security and hierarchical password control for centralized management

  • Reduced wiring via remote RTD’s using the RMIO module and support for 3 internal RTDs

  • Advanced power system and switchgear diagnostics

  • Customized motor overload curve Flex curves

  • Detailed Motor Health Report with critical data

  • Switchgear diagnostics and easy troubleshooting by CT/VT supervision, trip/close circuit supervision and LED/IO Test Mode

  • Drawout design simplifies testing, commissioning and maintenance, thereby increasing process uptime

  • Flexible communications with multiple ports and protocols allowing seamless integration

  • Robust design exceeding industry standards, with Automotive Grade components and advanced testing procedures such as accelerated life cycle testing

  • Migration of legacy MII Family relays to the 3 Series platform

  • Intuitive configuration software and user-friendly logic configuration tool


  • Protection and control of LV or MV motors of various sizes

  • Protection of pumps, conveyors, fans, compressors, and others in process or manufacturing industries.

  • Applications requiring fast and secure communications

  • Harsh environments requiring protection against corrosive chemicals and humid environments

Key Features

Protection and Control

  • Thermal model biased with RTD and negative sequence current feedback

  • Under Voltage

  • Over Voltage

  • Under/Over Frequency

  • Phase and ground TOC and IOC

  • Start supervision and inhibit

  • Mechanical Jam

  • Current Phase Reversal

  • Acceleration Time

  • Undercurrent / Underpower

  • Starts per Hour

The 339 motor protection systems is designed to protect and manage various sizes of LV and MV asynchronous motors and driven equipment. Flexible and powerful, the 339 provides advanced motor protection, control and monitoring in one integrated, economical drawout or non-drawout design. The 339 contains a full range of self contained protection and control elements as detailed in the Functional Block Diagram and Features table.

Monitoring & Metering

  • Comprehensive metering

  • Programmable oscillography up to 32 samples per cycle and digital states

  • SNTP or IRIG-B clock synchronization

  • 4X20 character LCD display

  • Control panel with 12 LED indicators

  • Motor health and switchgear diagnostics including breaker monitoring, CT/VT and close/trip coil supervision

  • Relay health diagnostics


  • Front USB and rear serial, Ethernet and Fiber ports

  • Multiple Protocols: IEC 61850, MODBUS TCP/IP, MODBUS RTU, DNP 3.0,IEC60870-5-104, IEC60870-5-103

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Block Diagram and Features Table

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UR Switch Module

Multilin 339 Brochure

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