GE Grid Solutions UR8LV CT/VT Module

Technical Dossier

Product Details And Specifications

GE UR Series Technical Notes

The GE UR (Universal Relay) Series is GE Grid Solutions' flagship platform for numerical protection, control, and monitoring in high-voltage and extra-high-voltage substation environments. Deployed across chemical processing plants, nuclear power stations, oil refineries, offshore platforms, and transmission utilities worldwide, the UR Series represents one of the most widely installed protection relay architectures in critical infrastructure. Its modular, rack-based hardware design allows end users to configure purpose-built relay systems for transformer protection, line protection, bus protection, motor protection, and generator protection — all within a standardized chassis and firmware ecosystem. The platform's longevity, spanning from the late 1990s to present-day active production, has resulted in an enormous installed base that continues to require spare parts, replacement modules, and lifecycle support.

The Evolution of UR Series Architecture

The UR Series was introduced by GE Multilin in the late 1990s as a successor to earlier electromechanical and first-generation digital relay platforms. The architecture is built around a universal chassis (UR chassis) accepting interchangeable I/O, CPU, power supply, and communications modules via a proprietary backplane bus. Early UR firmware (version 2.x–4.x) supported basic ANSI protection functions with serial communications (RS-485, DNP3). Subsequent generations introduced IEC 61850 GOOSE messaging, IEEE 1588 precision time protocol, and expanded analog input capacity. The UR8LV module specifically addresses CT (Current Transformer) and VT (Voltage Transformer) analog input conditioning — a foundational hardware layer for all protection functions. Compatibility across UR chassis generations (UR-8, UR-6, UR-4 slot counts) requires careful cross-referencing of module revision levels and firmware baselines. Obsolete early-revision modules (pre-2005) may require firmware downgrade or hardware adapter rings for backward integration. The platform has entered a mature lifecycle phase; GE Grid Solutions continues to manufacture select modules while others are designated End-of-Active-Production (EOAP), making third-party spare parts sourcing critical for long-term substation maintenance programs.

UR Series Full Catalog & Functionalities (SKU List)

The following SKUs represent verified, commonly deployed modules within the GE UR Series platform. Modules are categorized by functional role:

CT/VT Analog Input Modules

• UR8LV: 8-slot CT/VT analog input module; conditions current and voltage transformer signals for protection algorithms.
• UR6LV: 6-slot CT/VT analog input module; standard analog front-end for mid-size UR chassis configurations.
• UR4LV: 4-slot CT/VT analog input module; compact analog input for smaller UR relay builds.
• UR8LH: 8-slot high-burden CT/VT input module; designed for high-impedance differential protection schemes.

Digital Input / Output Modules

• UR8D: 8-slot digital I/O module; 16 optically isolated digital inputs, 8 output relays for trip/close/alarm circuits.
• UR6D: 6-slot digital I/O module; standard contact I/O for protection scheme logic.
• UR8DO: 8-slot high-speed digital output module; fast-operate output contacts for high-speed tripping applications.
• UR8DI: 8-slot digital input-only module; expanded binary status monitoring for complex substation schemes.

CPU / Processing Modules

• UR9CP: Main CPU module; hosts protection firmware, HMI interface, and primary communications stack.
• UR8CP: Legacy CPU module; earlier processing generation, compatible with firmware versions up to 7.4x.
• UR7CP: Compact CPU module; used in single-function relay configurations with reduced I/O requirements.

Communications Modules

• UR8CM: IEC 61850 / Ethernet communications module; supports GOOSE, MMS, and IEEE 1588 PTP.
• UR6CM: Dual-port fiber Ethernet communications module; ring topology support for substation LANs.
• UR8RS: RS-485 / RS-232 serial communications module; DNP3 and Modbus RTU protocol support.

Power Supply Modules

• UR9PS: Wide-range DC power supply module; 24–250 VDC input, internal DC/DC conversion for UR backplane.
• UR8PS: Standard DC power supply module; 48–125 VDC nominal, redundant supply capable.
• UR6PS: Compact power supply module; for 6-slot chassis configurations with reduced load requirements.

Quality Control for the UR Series Range

The GE UR Series employs a high-density backplane bus architecture that requires module-level functional verification before installation in live protection systems. DriveKNMS applies the following test protocol to all UR Series modules prior to shipment:

• Backplane Bus Continuity Test: Verification of all edge connector pins against GE Multilin backplane pinout specifications to detect bent, oxidized, or broken contacts.
• Analog Input Calibration Check (CT/VT Modules): For modules including the UR8LV, analog input channels are stimulated with calibrated current and voltage signals; output values are compared against GE factory calibration tolerances (±0.1% for metering-class inputs).
• Digital I/O Functional Test: Each input optocoupler and output relay contact is individually exercised; operate times are measured and logged against GE specifications.
• Firmware Compatibility Verification: CPU modules are booted and firmware version confirmed; compatibility with target relay type (T60, L90, C60, etc.) is cross-checked.
• Insulation Resistance Test: 500 VDC megger test applied across I/O terminals to chassis ground; minimum 100 MΩ acceptance criterion.
• Visual and Mechanical Inspection: PCB inspection for corrosion, component damage, and capacitor condition; front panel and ejector latch integrity verified.