GE Multilin 850 Feeder Protection Relay: Functions

Short answer

The Multilin 850 is the feeder protection relay of the GE Vernova Multilin 8 Series family. It protects one or two medium-voltage feeders, overhead or underground, in utility and industrial networks, with overcurrent, directional, voltage, frequency, autoreclose, breaker failure and arc flash detection functions, and it is set up with EnerVista.

What it is and where it is used

The Multilin 850 is the feeder protection relay of the Multilin 8 Series family from GE Vernova. The manufacturer presents it for the protection, control and monitoring of one or two medium-voltage feeders, overhead or underground, as primary or backup protection in utility and industrial networks. It is also used as a bay controller, with a single-line diagram on the display. See also GE Multilin 350, 345 and 339 relays.

You will find it in medium-voltage switchgear of distribution substations, in industrial plants and as a replacement for earlier-generation Multilin relays (SR 750 and 760). For background, see protective relays and radial feeder protection schemes.

Main functions

Function	ANSI / IEEE C37.2	Comment
Phase, neutral, ground and sensitive ground overcurrent	50/51, 50N/51N, 50G/51G	Primary protection (guide)
Directional elements	67/67N	Loops and networks with generation (directional units)
Under/overvoltage, frequency	27, 59, 81	Abnormal conditions (frequency)
Breaker failure	50BF	Local backup (guide)
Thermal overload	49	Sustained overload
Autoreclose	79	Overhead networks (guide)
Synchronism check	25	Closing between sources

GE Vernova also lists cold load pickup, switch onto fault, broken conductor detection and integrated arc flash detection with light sensors supervised by overcurrent, which reduces the incident energy in the switchgear. According to the manufacturer, the relay runs its protection cycle every 2 ms. To go further: arc flash relays ABB REA and VAMP.

For logic, the 8 Series family uses FlexLogic, the programmable logic editor from GE Vernova. It is used to build interlocks, blocking and transfer schemes without extra wiring, but it is also where an error hides most easily, and it may not show up until the day of the fault.

Communications and IEC 61850

The GE Vernova brochure lists IEC 61850 Edition 2, PRP redundancy (IEC 62439), Modbus RTU and TCP, DNP3, IEC 60870-5-104 and IEC 60870-5-103. It adds cybersecurity features (authentication with a RADIUS server, role-based access control and logging of security events through Syslog) and optional Wi-Fi for on-site configuration and diagnostics download. If you need a refresher on the protocols, see DNP3, IEC 60870-5-104 and GOOSE.

Events and oscillography

The 850 stores fault and event records and oscillography of disturbances, plus a data logger for analog values over periods of hours or days. Everything is downloaded with EnerVista 8 Series Setup and can be exported as COMTRADE (IEEE C37.111 / IEC 60255-24) for analysis with other tools. The data log is very useful for understanding trips caused by overload or cold load pickup, which do not show up in an oscillography record of a few cycles.

Where the 850 fits within the 8 Series

The 850 is a member of the Multilin 8 Series platform. GE Vernova’s firmware 4.35 release notes (published in August 2026) mention the 845, 850, 859, 869 and 889 models as products of the platform, and refer to the 850-E variant when they discuss the display with the single-line diagram. The same notes refer to the 869 with the synchronous motor option and to the 889 as generator protection, so the series covers feeders, motors and generators. What matters in the field is that they share the setup tool and the FlexLogic logic, so whoever knows one finds their way around the others.

Alongside it there are two feeder variants for other applications: the 850P, for multiple feeders in pad-mounted switchgear or ring main units (RMU), and the 850D. According to the 850P brochure:

it manages up to 4 feeders, with up to 12 current transformers for 3-way or 4-way equipment;
it accepts six low-energy analog (LEA) inputs or four voltage inputs;
it offers up to 57 digital inputs and 22 digital outputs;
it includes a configurable single-line diagram of up to six pages to control up to three breakers and nine disconnect switches with interlocking, an annunciator of up to 36 alarms according to ISA 18.1 and 20 virtual pushbuttons;
it runs a fast protection pass every 2 ms;
it communicates over IEC 61850 Ed. 2, IEC 62439/PRP, Modbus RTU and TCP/IP, DNP3.0, IEC 60870-5-104 and IEC 60870-5-103, and allows configuration and diagnostics over Wi-Fi.

If your relay is a single-feeder 850, these 850P figures do not apply as they stand. They are useful to know that, in this series, the same configuration concept extends to switchgear with several outgoing feeders.

Firmware versions: what to know before upgrading

GE Vernova publishes release notes for the whole 8 Series, which show corrections that affect the 850:

Closed upgrade paths. Versions 1.2x or lower cannot be upgraded to 1.3x or higher, and versions 3.x or lower cannot be upgraded to 4.x; in those cases GE asks you to contact the manufacturer. In other words, the installed firmware determines which options you have.
DNP3 over Ethernet. Up to version 4.35, if the DNP master suffered intermittent communication losses, the relay could lock up and require a manual restart; firmware 4.35 reconnects it automatically. It is one of the reasons why a DNP3 or IEC 104 link that keeps dropping cannot be explained by the network alone.
Link loss alert (LLA). On relays with communication option 3A, the function might not operate; it was corrected in 4.35.
850-E display. Leaving the single-line diagram page with the “Home” button, with a breaker operation selected but not executed, could restart the relay; the fix is in 4.35.
IEC 61850. Version 4.34 added support for control interlocking (the CILO logical node), and GE documents adjustments to GOOSE packets; see GOOSE interlocking with CILO and CSWI.

Software: GE states that the 8 Series EnerVista Setup is version 12, compatible with Windows 7, 8.1, 10 and 11. Before any upgrade the settings are backed up, and the firmware and software versions are recorded in the commissioning report.

Frequent technical questions

Replacing a 750/760: the settings conversion helps, but the curves, the logic and the input and output wiring change; everything has to be reviewed before energizing.
Arc flash trips: light-based detection depends on the location of the sensors and on current supervision; a misplaced or unsupervised sensor causes nuisance trips.
Sensitive ground: it requires the right current transformer and a setting consistent with the system grounding.
FlexLogic: a badly ordered equation blocks or enables functions in unexpected ways.
Trip on energizing: inrush and cold load pickup; see overcurrent trip on starting or energizing.

How we help

At Tiza Group we configure and review Multilin relays remotely, worldwide, with EnerVista: protection functions, FlexLogic, communications and IEC 61850, based on the protection study and the approved settings. See the scope in remote configuration of GE Vernova Multilin relays. If your 850 tripped and it is not clear why, send us the records for a relay trip analysis or write to us through the contact page.

References

IEEE C37.2, device function numbers.
IEC 60255-151, functional requirements for overcurrent protection.
IEC 61850 (series); IEC 62439-3, PRP.
IEEE C37.111 / IEC 60255-24, COMTRADE.
GE Vernova, Multilin 850 product page and brochure.

Frequently asked questions

What is the difference between the Multilin 850, 850D and 850P?

The 850 protects one or two feeders and also works as a bay controller. The 850D is intended for two feeders, with two sets of voltage inputs. The 850P was the multi-feeder version; GE Vernova states that it has been discontinued and recommends the 850D as the alternative.

Which protocols does the Multilin 850 support?

GE Vernova lists IEC 61850 Edition 2, PRP according to IEC 62439, Modbus RTU and TCP, DNP3, IEC 60870-5-104 and IEC 60870-5-103.

Can a Multilin 750 or 760 be replaced with an 850?

GE Vernova offers upgrade paths from the SR 735, 750 and 760, and the EnerVista software includes a settings conversion for these cases. The converted settings must always be checked against the current protection study before the relay is put into service.