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Multilin 850

Innovative feeder and bay controller in one box

The Multilin™ 850 relay is a member of the Multilin 8 Series protective relay platform and has been designed for the management, protection and control of feeder applications. The Multilin 850 is an integrated, one box solution, used to provide comprehensive protection, control and monitoring of underground and overhead single or dual feeders in industrial and utility power networks.

The Multilin 850 is also an ideal choice for bay control applications, with features including 12 switchgear control elements, a large color graphical display that supports configurable single line diagrams, an integrated annunciator panel, and 20 user configurable virtual pushbuttons.

With support for industry leading communications protocols and technologies, the 850 provides easy integration into new or existing SCADA or DCS for enhanced situational awareness. To simplify the migration and upgrade from an existing SR 750/760 or 735 protection relays, retrofit kits have been developed which significantly simplify the upgrade process.

850 Overview

Multilin 850 Overview

The Multilin 850 is an advanced feeder protection relay that provides high performance protection, high density I/O, extensive programmable logic and flexible configuration capabilities. With protection and control logic, the 850 allows for simplified coordination with upstream and downstream disconnect devices. The Multilin 850 supports both industrial and distribution utility feeders. Dual feeders (850D) and multi feeder (850P) in electrical applications are also supported.

As part of the 8 Series platform of relays, the Multilin 850 shares the advanced communications and cyber security features and EnerVista software suite that is common to the platform. 

Comprehensive feeder protection

  • One box solution with advanced logic and configuration flexibility to provide comprehensive primary or backup protection, control and monitoring for 2 feeders or for feeders with 2 sets of voltage inputs.

  • breaker diagnostics with high-end fault and disturbance recording

  • Integrated arc flash detection using light sensors supervised by overcurrent to reduce incident energy and equipment damage.

  • High-end cyber security such as AAA, Radius, RBAC and Syslog, enabling NERC CIP requirements.

  • Draw-out design simplifies testing, commissioning and maintenance, increasing process uptime.

  • Optional Wi-Fi connectivity minimizes system configuration and provides safe relay programming and diagnostic retrieval.

  • Patented environmental monitoring, providing visibility to changes in environmental conditions that can affect relay life.

Dual Feeder

Dual Feeder Protection

The Multilin 850D is designed for high performance protection, control and monitoring of up to two distribution feeders, and provides all the functionalities required for a distribution feeder including SOFT, under current and pole discordance. Extensive programmable logic and flexible configuration capabilities along with sequence coordination enable the 850D to comply with system coordination requirements.

850D key features:

  • Up to 2 feeders within one relay

  • Dual voltage banks with single feeder

  • High-end cyber security such as AAA, Radius, RBAC, and Syslog helps enable NERC® CIP requirements

  • Draw-out design simplifies testing, commissioning and maintenance, thereby increasing process uptime

  • Wi-Fi connectivity minimizes system configuration and provides safe relay programming and diagnostic retrieval

  • Relay environmental diagnostic information helps reduce system downtime

Multi Feeder

Multi Feeder Protection

The Multilin 850P relay has been designed for the management, protection and control of multi feeder applications supporting both traditional voltage inputs as well as Low Energy Analog (LEA) inputs. A maximum of 4 feeders can be supported by the 850P.

The 850P addresses the following customer challenges:


  • Extending asset life and optimizing performance for system uptime and greater return-on-investment

  • Reducing system downtime due to environmental occurrences and equipment failures

  • Securing CAPEX funding to update outdated systems

  • Recruiting new talent to resupply the retiring / aging workforce while keeping up with technology advances

  • Visibility on downstream distribution points

  • Inefficient truck roll outs in event of outage


Key benefits

  • Reduce number of IEDs in the system, resulting in lower capital and O&M costs, and smaller battery sizing

  • Mean time to repair less than 15mins with field swappable PSU, draw out construction and ready to consume service reports

  • Extend asset life with built-in environmental monitoring, battery and advanced breaker monitoring

  • Same device-based solution (850D/P) reduces training needs, standardizes SKUs and harmonizes the user and operational experience


Arc Flash

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 850 can be configured to indicate the health of the sensors and its connections to the relay.

Monitoring & Diagnostics

Monitoring & Diagnostics

The Multilin 850 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.


Breaker Health Monitoring

The breaker is monitored by the relay not only for detection of breaker failure, but also for the overall “breaker health” which includes:

  • Breaker close and breaker open times

  • Trip circuit monitoring

  • Spring charging time

  • Per-phase arcing current

  • Trip counters

Data Logging

The Multilin 850 delivers comprehensive data logging providing the recording of 16 analog values selected from any analog values calculated by the relay. This data capture flexibility allows the operator to measure power factor or reactive power flow (for example), for several hours or even days, enabling detailed analysis and corrective action to be taken.



Environmental Monitoring

The 8 Series built-in environmental awareness feature (patent “Systems and methods for predicting maintenance of intelligent electronic devices”) collects the histograms of each operating condition from the point the device is put into service. Monitored environmental conditions include temperature, humidity and transient voltage. These parameters are now available as Flexelement to output alarms in case of limits reached due to Temperature, humidity or surges.

Trip and Close Circuit Monitoring

The 850 relay provides Trip and Close Circuit Monitoring elements


Breaker Arcing Current

This element calculates an estimate of the per-phase wear on the breaker contacts by measuring and integrating the current squared passing through the breaker contacts as an arc. When the threshold is exceeded in any phase, the relay can set an output operand and set an alarm.


Retrofit Kit

8 Series Retrofit Kit


Explore the 8 Series Retrofit Kit

Retrofit Existing SR 735 or SR 750/760 Devices to the Multilin 850 in Minutes

Traditionally, retrofitting an existing relay has been a challenging, time consuming task often requiring re-engineering, new drawings, panel modifications, re-wiring and re-testing.

The 8 Series Retrofit Kit provides a quick, 3-step solution to upgrade previously installed SR 735 or SR 750/760 Devices. With the new 8 Series Retrofit Kit users are able to install the 850 Feeder Management System without modifying existing cutouts and wiring, and without any drawing changes or re-engineering.

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Multilin 850 feeder protection relay functional block diagram

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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.

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Multilin 850 Brochure

Multilin 850 Manual

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