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Multilin 845 Comprehensive Protection & Management
for Power & Distribution Transformers
Multilin 845 Protection, Management for Power and Distribution Transformers

The Multilin™ 845 Transformer Protection System is a member of the Multilin 8 Series protective relay platform and has been designed for the protection, control and management of 2- and 3-winding power and distribution transformers in both utility and industrial applications.

The Multilin 845 provides advanced functionality for a wide range of transformer applications delivering high-speed protection, customizable programmable logic, advanced transformer monitoring and diagnostics, and support for the latest communications protocols for easy integration into new or existing power systems.

The Multilin 845 delivers comprehensive transformer health monitoring, diagnostics, and reporting with integrated connectivity to composite and multiple gas transformer DGA solutions such as, GE’s Kelman Transformer Monitoring devices, delivering actionable analytics for asset optimization and transformer life extension.

Key Benefits
  • Comprehensive transformer protection including fast operating differential protection, unique CT saturation and directional detection
  • Advanced transformer monitoring, diagnostics and disturbance recording extending asset life
  • Integrated protection & DGA for continuous transformer monitoring Integrated arc flash detection using light sensors supervised by over current to reduce incident energy and equipment damage
  • High-end cyber security tools such as AAA, Radius, RBAC, and Syslog enabling NERC CIP requirements Draw-out design simplifies testing, commissioning and maintenance
  • Optional Wi-Fi connectivity minimizes system configuration and facilitates safe relay programming and diagnostic retrieval
  • Monitored environmental conditions helps reduce system downtime
  • High flexibility for customized protection and control logic

The Multilin 8 Series platform delivers the highest level of quality, reliability and performance with…
Innovative Technology & Design
  • Elimination of electrolytic capacitors
  • Advanced diagnostics with unique algorithms ensuring asset protection is never compromised
  • Single set-up and configuration across the platform
  • Built-in field swappable power supply
  • Enhanced relay draw-out construction
  • Advanced and flexible communication offerings simplifying system integration
  • Embedded communications offerings including: IEC61850 Ed2, IEC62439/PRP, Modbus RTU & TCP/IP
Exceptional Quality & Reliability
  • IPC A-610-E Class 3 Manufacturing standards – highest industry standards for electronic manufacturing
  • 100% Environmental Stress Screening and full functional testing
  • Rated for IP54 applications
Uncompromising Service & Support
  • Covered under GE’s 10 year warranty plan
  • Fully designed, tested and assembled at GE facilities
Multilin 845 Overview

The Multilin 845 utilizes advanced functionality enabling high-speed protection and control, easy-to-use single-screen device configuration enabling faster start-up and commissioning, as well as detailed transformer health reports and fault analysis simplifying identification of potential transformer issues before they become critical failures.

  • Primary and back-up protection and management of small, medium and larger power and distribution transformers, autotransformers and reactors
  • Designed for Utility (Transmission & Distribution) or Industrial applications
  • Integrated transformer protection, monitoring diagnostics and transformer health visualization
  Multilin 845 feeder protection relay functional block diagram
27 Voltz per hertz
27X Auxiliary Undervoltage
27P Phase Undervoltage
27X Auxiliary Undervoltage
49 Cable Thermal Model
50/87 Instantaneous Differential Overcurrent
50BF Breaker Failure 
50G Ground Instantaneous Overcurrent
50N Neutral Instantaneous Overcurrent
50P Phase Instantaneous Overcurrent
50_2 Negative Sequence Instantaneous Overcurrent
51G Ground Time Overcurrent
51N Neutral Time Overcurrent
51P Phase Time Overcurrent
51_2 Negative Sequence Time Overcurrent
59N Neutral Overvoltage
59P Phase Overvoltage
59X Auxiliary Overvoltage
67G Ground Directional Element
67N Neutral Directional Element
67P Phase Directional Element
81O Overfrequency
81U Underfrequency
81R Frequency Rate of Change
87G Restricted Ground Fault (RGF)
87T Transformer differential
Protection & Control

As part of the Multilin 8 Series platform, the Multilin 845 provides superior, high-speed protection and control. With proven protection algorithms, the 845 provides a full range of selectively enabled protection and control elements.

Percent Differential Protection

The 845 provides enhanced security by including both restrained and unrestrained (instantaneous) differential protection. The percent differential element is based on a configurable dual-breakpoint/dual-slope differential restraint characteristic with inrush and overexcitation inhibits based on 2nd & 5th harmonics. The restraint current is calculated as a maximum of the internally compensated currents for better through-fault stability under CT saturation conditions.

The percent characteristic allows the element to account for both DC and AC saturation of the current transformers. The “cubic spline” curve characteristics enables the relay to perform accurately for restraint current in range between the two slope breakpoints.

Differential vs. Restraint Characteristic (ld

The settings for the dual-slope, dual-breakpoint characteristic provides higher flexibility for shaping up the characteristic and achieving better sensitivity and security.

Typical Wiring for 2- and 3-Winding Transformers

Multilin 869 Stator Differential
Integrated Arc Flash Protection

The Multilin 8 Series supports an integrated arc flash module providing constant monitoring of an arc flash condition within the switchgear, motor control control centers, or panelboards. With a 2ms protection pass, the 8 Series is able to detect light and overcurrent using 4 arc sensors connected to the 8 Series relay. In situations where an arc flash/fault does occur, the relay is able to quickly identify the fault and issue a trip command to the associated breaker thereby reducing the total incident energy and minimizing resulting equipment damage.

Self-monitoring and diagnostics of the sensors ensures the health of the sensors as well as the full length fiber cables. LEDs on the front panel display of the 845 can be configured to indicate the health of the sensors and its connections to the relay.

845 integrated arc flash protection
Fast, reliable arc flash protection with light-based arc flash sensors integrated within the Multilin 8 Series of protection & control devices. With arc flash detection in as fast as 2msec, the costs associated with equipment damage and unplanned downtime is significantly reduced.
Monitoring & Diagnostics

The Multilin 845 includes high accuracy metering and recording for all AC signals. Voltage, current, and power metering are built into the relay as a standard feature. Current and voltage parameters are available as total RMS magnitude, and as fundamental frequency magnitude and angle.

Data Logging & Learned Data

The 845 captures key electrical and DGA data values during transformer energization to trend and analyze transformer performance. Data is summarized and presented to operators through a pre-formatted Health Report to clear indication of changes to measured parameters. Up to 365 records are supported within the 845 relay. Up to 365 latest records are supported in the 845 relay. The data, when input cumulatively to the transformer model screens helps in visualizing trends and correlating key transformer electrical and DGA parameters.

Learn Data Transformer Learned Data Record Visualization
Integrated Electrical and DGA for Comprehensive Transformer Monitoring & Diagnostics

The Multilin 845 offers advanced transformer health monitoring and diagnostics through advanced notification of potential issues before they become critical. The Multilin 845 features detailed learned data, summarized pre/post-fault records, and integration with GE’s DGA devices to collect, trend, and analyze a transformer’s fault gasses. This enables operators to minimize costly unplanned outages and equipment failures.


The 845 provides advanced communications technologies for remote data and engineering access, making it easy and flexible to use and integrate into new and existing infrastructures. Direct support for fiber optic Ethernet provides high-bandwidth communications, allowing for low-latency controls and high-speed file transfers of relay fault and event record information. The 845 also supports two independent IP addresses, providing high flexibility for the most challenging of communication networks. Two independent network ports enables the 845 to connect with the primary protection network and the secondary monitoring network to deliver integrated asset monitoring and diagnostics by combining protection and DGA data.

Providing several Ethernet and serial port options and supporting a wide range of industry standard protocols, the 845 enables easy, direct integration into DCS and SCADA systems. The 845 supports the following protocols:

  • IEC 61850 Ed2, IEC 62439 / PRP
  • DNP 3.0, IEC 60870-5-103, IEC 60870-5-104
  • Modbus RTU, Modbus TCP/IP

The 845 has two interfaces as USB front port and Wi-Fi for ease of access to the relay. Wi-Fi Connectivity:

  • Simplify set-up and configuration
  • Simplify diagnostic retrieval
  • Eliminate personnel in front of switchgear
  • WPA-2 security
8 Series
Software & Configuration

The EnerVista™ suite is an industry-leading set of software programs that simplifies every aspect of using the Multilin 845.

EnerVista provides all the tools to monitor the status of the protected asset, maintain the device and integrate the information measured by the Multilin 8 Series, into SCADA or DCS process control systems. The ability to easily view sequence of events is an integral part of the setup software, as postmortem event analysis is critical to proper system management.

EnerVista Launchpad

The setup tools within Launchpad allow for the configuration of devices in real-time, by communicating via serial, Ethernet or modem connections, or offline by creating device setting files to be sent to devices at a later time.

8 Series Setup Software

8 Series Setup Software is single setup and configuration tool across the platform and can reduce device setup and configuration time.

Simplified Setup & On-Going Maintenance

845 set up