The 345 is a microprocessor-based system for primary and backup protection of low and medium voltage power transformers. The 345 offers advanced algorithms for automatic magnitude and phase compensations for more than twenty types of two winding transformers, fast and secure biased differential protection with dual slope, dual breakpoint characteristic.
Proven and secure high-speed protection
Integrated transformer thermal monitoring for asset management maintenance optimization
Ground current supervised sensitive ground fault protection for detection of ground faults down to 5% of the winding
Assignable CT inputs providing flexibility
Seamless integration into most communication
multiple communication networks including USB, Serial, Fiber or copper Ethernet
Unique draw-out construction to reduce the use of test switches
Small footprint easy on new installations or retrofits
Simplified transformer and protection setup right from the main menu
Low and medium voltage two winding power transformers
Harsh environments requiring protection against corrosion and humidity
Reactors and autotransformers
Applications requiring fast and secure communications
Second harmonic inrush and fifth harmonic over-excitation inhibits
Instantaneous differential
Restricted Ground Fault
Percent Differential Protection
Thermal model
Phase and Ground Timed and Instantaneous over-current
Neutral Timed and Instantaneous over-current
Negative Sequence Timed over-current
Breaker Failure
Logic elements
The 345 transformer protection system is designed to protect and control small to medium size power transformers. Flexible and powerful, the 345 provides advanced transformer protection, control and monitoring in one economical draw-out design. The 345 contains a full range of self-contained protection and control elements as detailed in the Functional Block Diagram and in the Features table.
Current Metering
RTD Temperature
Event Recorder: 256 events with 1ms time stamping
Oscillography with 32 samples per cycle and digital states
IRIG-B clock synchronization
Motor health diagnostics
Security audit trail
The 345 continuously measures and computes the following AC signals indicating the health of the protected transformer:
Phase winding currents
Winding ground current
Winding neutral current
Winding negative sequence current
Differential and restraint currents per-phase
Winding ground differential current
Percent 2nd and 5th harmonics differential currents per phase
Percent thermal capacity per-phase
The states of all digital inputs/outputs are provided through the actual values either from the summary pages and individually. This includes:
States of contact inputs
States of virtual inputs
States of remote inputs
States of relay outputs
States of logic elements
The 345 provides settable trip coil circuit monitoring feature per transformer breaker, that can produce alarm and trigger auxiliary output relay upon detection of trip coil circuit discontinuity.
Sixteen logic elements available for simple logic for applications such as manual control, interlocking, and peer to peer tripping.
4X20 character LCD display
Control panel with 12 LED indicators
Front USB and rear serial, Ethernet and Fiber ports
Easy integration into new or existing infrastructure. With several ethernet and serial port options, and a variety of protocols, the 345 provides advanced and flexible communication selections for new and existing energy management, SCADA, and DCS systems.
The 345 incorporates the latest communication technologies making it the easiest and the most flexible feeder protection relay for use and integration into new and existing infrastructures. The 345 relay provides the user with one front USB and one rear RS485 communication port. It also offers the option of an additional rear communication port with Ethernet Fiber and Copper. Through the use of these ports, continuous monitoring and control from a remote computer, SCADA system or PLC is possible. With our advanced draw-out construction, the 345 relay can be drawn-out without having to disconnect any communication cables.
The 350 supports popular industry standard protocols enabling easy, direct integration into electrical SCADA and HMI systems. The protocols supported by the 345 include:
IEC 61850
DNP 3.0
Modbus RTU
Modbus TCP/IP
IEC 60870-5-103
IEC 60870-5-104
These protocols make it easy to connect to a Utility or Industrial automation system,
eliminating the need for external protocol converter devices.
The EnerVista™ suite is an industry leading set of software programs that simplifies every aspect of using the 345 relay. The EnerVista™ suite provides all the tools to monitor the status of the protected asset, maintain the relay, and integrate the information measured into DCS or SCADA monitoring systems. Convenient COMTRADE and sequence of event viewers are an integral part of the 345 setup software and are included to ensure proper protection and system operation. Learn More
Access Control
Multilin devices and relays are designed with simple but powerful security to enable reliability and compliance for virtually any project or implementation. With support for multi-level permissions and multi-factor supervisory controls, Multilin devices can help you manage the integrity of your system during commissioning, testing, implementation, and beyond.
The UR Family provides separate authentication for settings and commands to the system. In addition, as discrete authentications for local and remote access, it also provides a supervisory control factor that can lock or unlock a device for configuration changes and other modifications.
Intrusion Detection
Multilin’s family of protection and control products can also help enable your security perimeter and intrusion detection programs. By providing essential alarming and logging of critical events, Multilin devices can help you detect potential breaches within your system and allow you to respond quickly and effectively. Specifically, unsuccessful access attempts are logged, alarmed, and lead to potential attackers being locked out. This ensures the reliability of your system during questionable activity
control factor that can lock or unlock a device for configuration changes and other modifications.
Auditing and Reporting
With the Security Audit Trail reporting feature and support for Event logging of key activities such
as configuration changes, Multilin devices can help ensure device and protection system integrity,
and perform forensic auditing of activities and changes for compliance.
Protection & Control 
