GE Multilin UR Series Modules

Technical Dossier

Product Details And Specifications

GE Multilin UR Series: Comprehensive Module Range and Technical Overview

The GE Multilin Universal Relay (UR) platform is one of the most widely deployed digital protection and control relay families in global heavy industry. Installed across high-voltage substations, chemical processing plants, nuclear generating stations, offshore oil platforms, and petroleum refineries, the UR Series provides a standardized hardware chassis that accepts interchangeable function-specific modules. Its modular architecture allows a single physical platform to serve as a distance relay, transformer differential relay, line current differential relay, or bus protection relay depending on the firmware and I/O configuration installed. The UR platform is the successor to GE Multilin's earlier SR Series and has itself been succeeded in new installations by the UR+ and Reason series, though the installed base of UR hardware remains enormous and active maintenance demand continues globally.

The Evolution of UR Series Architecture

The UR platform was introduced in the late 1990s as a response to the industry need for a common hardware chassis across multiple protection functions. The original UR chassis used a 19-inch rack-mount form factor with a modular slot-based backplane. Early firmware versions (pre-4.0x) supported basic ANSI protection functions with serial communications via RS-485 and DNP3. The introduction of IEC 61850 GOOSE messaging support in firmware 5.x marked a significant architectural shift, enabling peer-to-peer relay communication without a central controller — a critical requirement for modern substation automation.

The UR 6CH designation refers to the 6-slot chassis configuration, which accommodates a CPU module, power supply module, and up to four I/O or communications modules. This chassis size is the most common in field installations and supports the full range of UR function types. Larger 8-slot and 10-slot chassis variants exist for applications requiring expanded I/O. Compatibility between chassis generations is constrained by backplane revision: early backplane revisions (A, B) are not compatible with later CPU modules without a full chassis replacement. Engineers managing aging UR installations must verify backplane revision before ordering replacement CPU or I/O modules.

The UR platform entered its mature/end-of-active-development phase with the release of the UR+ platform. GE Grid Solutions (now part of GE Vernova) continues to provide firmware maintenance releases and spare parts support for the UR Series, but new feature development is concentrated on UR+. For operators of UR-based protection schemes, long-term maintenance planning should account for the increasing lead times on original factory modules and the growing importance of qualified refurbished and tested spare parts.

UR Series Full Catalog & Functionalities (SKU List)

The following SKUs represent the core of the GE Multilin UR Series platform. Each entry identifies the relay type and its primary protection function. All models share the common UR chassis and backplane architecture.

UR 6CH: 6-slot UR chassis, standard 19-inch rack mount, accepts all UR module types.
D30: Line distance protection relay, 21/21N zone distance, single or three-phase.
D60: Line distance protection relay with advanced teleprotection scheme support (POTT, PUTT, DCB).
T35: Transformer protection relay, dual-slope differential, REF, overexcitation (24).
T60: Transformer management relay, full differential plus extensive backup protection functions.
L90: Line current differential relay, 87L function, fiber or pilot wire channel interface.
C60: Breaker protection relay, 50BF, 52, reclosing, synchronism check (25).
C30: Universal controller relay, configurable I/O, non-protection automation and control applications.
F35: Multiple feeder protection relay, up to three feeders in a single chassis, 50/51/67N.
F60: Feeder management relay, full overcurrent, directional, and reclosing suite.
G30: Generator protection relay, 87G differential, 40 loss of field, 46 negative sequence.
G60: Generator management relay, comprehensive generator protection including 100% stator ground (27TN/59TN).
M60: Motor protection relay, 49 thermal model, 50/51, 46, 66 starts per hour.
B30: Bus differential protection relay, low-impedance differential, up to 6 feeders.
N60: Network stability and synchrophasor relay, PMU-class phasor measurement, IEEE C37.118.
URplus CPU: Replacement CPU module for UR chassis, firmware field-upgradeable via front USB port.
UR 8CH: 8-slot UR chassis variant for expanded I/O applications.
UR PSU: Power supply module, 125/250 Vdc or 120/240 Vac input options.
UR CT/VT: Analog input module, 4 CT inputs + 4 VT inputs per module, 16-bit ADC.
UR DI: Digital input module, 16 optically isolated contact inputs, configurable threshold voltage.
UR DO: Digital output module, 8 form-A or form-C relay output contacts, rated 8A continuous.

Sourcing Hard-to-Find & Obsolete UR Series Parts

DriveKNMS maintains a dedicated inventory program for GE Multilin UR Series modules, with particular focus on components that have been discontinued by the original manufacturer or that carry extended factory lead times. The UR platform's modular design means that a single failed module — a CPU, a CT/VT analog input card, or a communications adapter — can render an otherwise functional relay inoperable. Replacing the entire relay is often cost-prohibitive and requires full protection scheme re-commissioning. DriveKNMS provides tested individual module replacements as an alternative.

All sourced UR modules undergo functional verification against GE Multilin's published test procedures before shipment. Firmware version compatibility is verified against the customer's chassis backplane revision and existing module set. Where a direct replacement is unavailable, DriveKNMS engineering staff can advise on compatible substitute modules or chassis upgrade paths that preserve existing wiring and CT/VT connections.

For end-of-life UR installations where the entire protection scheme requires replacement, DriveKNMS can supply complete tested UR relay assemblies configured to customer specifications, reducing site commissioning time compared to new-build alternatives.

Quality Control for the UR Series Range

The UR Series backplane uses a proprietary high-speed serial bus for inter-module communication. Faults in this bus — caused by connector wear, backplane trace damage, or module firmware incompatibility — produce intermittent protection function failures that are difficult to diagnose without dedicated test equipment. DriveKNMS employs a UR-specific test bench that replicates the full backplane environment, allowing each module to be exercised under simulated load conditions before dispatch.

Test procedures for UR modules include: power supply output voltage and ripple verification under full load; CPU module boot sequence and firmware integrity check; analog input module accuracy calibration against traceable reference standards (CT ratio error <0.1%, VT ratio error <0.1%); digital input threshold voltage verification across the full specified range; digital output contact resistance and operate time measurement; and communications module loopback testing for all installed protocols (DNP3, IEC 61850, Modbus, IEEE C37.118). Each module ships with a test record documenting measured values against GE Multilin's published acceptance criteria.