GE MULTILIN UR8LH is an analog acquisition accessory module for the UR series universal protective relays. Positioned as a 4-channel CT plus 4-channel VT signal acquisition unit with enhanced diagnostic functions, it is exclusively compatible with the new-generation 9-digit CPU main control backplanes of the UR series.
Its core function is to isolate, sample and perform analog-to-digital conversion on AC analog signals output by on-site transformers, then transmit processed data to the protective host, enabling accurate collection of primary-side current and voltage values of power systems.
Equipped with an independent hardware diagnostic circuit, the module performs real-time monitoring of CT secondary circuit faults including open circuits, short circuits, wire breakages and phase sequence anomalies, as well as VT circuit malfunctions such as voltage loss and ground faults. Corresponding alarm signals are simultaneously uploaded to the device’s human-machine interface and background monitoring system.
Adopting a pluggable backplane gold-finger connection architecture, the unit supports installation, replacement and system capacity expansion without additional wiring modifications. It caters to measurement, metering and protection logic calculation requirements for critical power circuits in transformer substations, generator sets and industrial power distribution systems. Featuring a wide temperature and wide humidity hardware design, it can operate reliably under harsh working conditions including indoor power distribution rooms, outdoor box-type transformers and offshore platforms.
Model Code Breakdown
Segment-by-segment decoding of the full UR8LH part number, with hardware configuration definitions for each character segment
- UR: Product series identifier, denoting modular expansion modules of the GE Multilin Universal Relay series
- 8: Total channel marker, indicating the module is equipped with 8 AC analog input channels in total
- L: Function classification code, representing mixed CT/VT signal acquisition with dedicated hardware circuitry for enhanced circuit diagnostics
- H: Hardware specification code, signifying wide-temperature industrial ruggedized variant; supports DIP switch selection between 1A and 5A CT secondary ratings, and features heavy-duty hardware shielding for superior electromagnetic interference resistance
Full Definition: 8-channel CT/VT acquisition module with enhanced diagnostics, wide-temperature industrial grade, belonging to the UR series
Product Features
Hardware Channel Specifications
- CT Input: 4 independent current acquisition channels; DIP switch configurable for 1A / 5A secondary current, with individual overcurrent limiting protection per channel
- VT Input: 4 independent voltage acquisition channels, compatible with standard transformer secondary voltage ratings of 100V and 220V
- Sampling Architecture: Dedicated independent analog-to-digital (AD) converter for each channel, with galvanic isolation between channels to eliminate cross-phase signal crosstalk
- Self-Diagnostic Hardware: CT secondary open-circuit / short-circuit detection, VT loss-of-voltage / single-phase ground fault detection, backplane bus communication fault detection, and module power supply status monitoring
Environmental & Mechanical Characteristics
- Operating Temperature: -40℃ to +70℃; Storage Temperature: -40℃ to +85℃
- Humidity Resistance: Continuous operation under 5%–95% relative humidity without condensation
- Vibration Resistance: 5–500 Hz frequency range, 5 g peak acceleration; Shock Resistance: 30 g shock load over 11 ms duration
- Mechanical Dimensions: 233mm × 112mm × 23mm, single-slot form factor compatible with standard UR chassis
- Weight: 350g, lightweight pluggable module for effortless single-person installation and removal with minimal load burden
Product Advantages
1. Superior Signal Diagnostics
Built with independent channel monitoring units, the module performs separate self-checks on the four CT channels and four VT channels, enabling precise pinpointing of faults in individual transformer circuits. Unlike conventional CT/VT modules that only generate general alarms, this feature drastically cuts fault troubleshooting time. Full enhanced diagnostic algorithms are activated with firmware version 5.20 or above, effectively mitigating risks of relay false tripping and failure to trip.
2. Wide Compatibility with Various Transformers
Hardware DIP switches support two standard CT secondary rated currents (1A and 5A), while VT inputs accommodate 100V and 220V standard secondary voltages. It fits transformers compliant with domestic and overseas power distribution standards without module replacement, eliminating the need to swap primary field equipment during project retrofits.
3. Optimized Cabinet Space Utilization
A single unit integrates 8 AC analog inputs (4 CT + 4 VT). Stackable expansion of multiple modules can replace several discrete acquisition boards. It reduces cabinet mounting space by 30% compared with traditional external signal conditioners and lowers overall cabinet manufacturing costs.
4. Stable Performance in Harsh Environments
Operating temperature ranges from -40℃ to +70℃, with continuous operation allowed under 95% non-condensing relative humidity. It has passed industrial qualification tests for 5g vibration and 30g shock loads, delivering long-term drift-free continuous operation for offshore oil & gas platforms, high-temperature metallurgical workshops and other demanding sites.
5. Fast Deployment & Legacy System Compatibility
Fully pluggable solder-free design allows complete removal and installation within 3 minutes after power cut-off. Its native backplane bus is compatible with all new-generation UR series main units. Existing UR protective devices only require a firmware upgrade to recognize the module, removing the cost burden of full main unit replacement for retrofits.
6. High-Precision Sampling & Metering
All channels feature ±0.5% full-scale sampling accuracy with 12-bit AD conversion chips and a 10ms instantaneous value response speed. It meets stringent precision requirements for high-accuracy energy metering, harmonic monitoring, unbalance protection and differential protection.
Application Industries
1. Power Transmission & Distribution
Urban 10kV/35kV/110kV substations, switching stations and ring main units, deployed for signal acquisition of line protection, bus differential protection and capacitor bank protection devices.
2. Power Generation Industry
Small and medium-sized hydropower units, turbo-generator sets, centralized booster stations for photovoltaic and wind power plants. Matched with generator protection and main transformer differential protection hosts to collect stator and rotor current & voltage signals.
3. Oil & Gas Industry
High-voltage power distribution rooms on offshore oil production platforms and onshore oil & gas gathering stations, serving power distribution protection systems that withstand harsh high-humidity and salt-fog environments.
4. Metallurgy & Heavy Industry
High-voltage distribution rooms in iron & steel smelting and non-ferrous metal smelting plants, capable of handling harmonic interference generated by high-power loads such as electric arc furnaces and rolling mills.
5. Rail Transit Industry
High-speed railway traction substations, main and section substations of urban metro systems, for analog signal acquisition of traction transformer and feeder protection.
6. Chemical & Water Treatment Industry
High-voltage power distribution systems in large chemical industrial parks, water supply plants and sewage treatment plants, realizing plant load monitoring and rapid short-circuit fault protection.
Product Comparison
UR8LH
Channel Configuration: 4 CT + 4 VT Core Advantages: Independent enhanced diagnostics for all channels, industrial wide-temperature design, DIP switch switching between 1A and 5A CT secondary current Applicable Scenarios: Standard circuits in medium & small substations, generator sets and industrial power distribution Positioning: Mid-range general-purpose acquisition module with enhanced diagnostic functions
URRLH
Channel Configuration: 8 CT + 8 VT Core Advantages: High-density 16 analog input channels for large-capacity circuit signal collection Applicable Scenarios: Large hub substations, multi-winding main transformer protection Positioning: High-end high-capacity acquisition module
UR8FV
Channel Configuration: 4 CT + 4 VT Core Advantages: Cost-effective basic version without independent enhanced diagnostic functions Applicable Scenarios: Simple low-voltage feeder protection, retrofit projects with limited budgets Positioning: Entry-level basic acquisition module
UR8GH
Channel Configuration: 4 CT + 4 VT Core Advantages: Optimized for high-precision energy metering and harmonic sampling Applicable Scenarios: Commercial power distribution and photovoltaic power stations requiring high-accuracy electric energy metering Positioning: Specialized metering acquisition module
UR8MH
Channel Configuration: 4 CT + 4 VT Core Advantages: Equipped with sensitive ground fault acquisition channels Applicable Scenarios: Ground fault protection for neutral ungrounded power grids and cable lines Positioning: Specialized acquisition module for ground fault protection
Compatible Supporting Products
Core Main Control Units (CPU Modules)
Full range of new-generation UR main CPUs including UR9EH, UR9GH, UR9HH, UR9JH and UR9KH. Legacy 8-digit CPU modules are incompatible with this module.
Complete Protective Relays
F35 Feeder Protection Relay T35 Transformer Protection Relay T60 Main Transformer Differential Protection Relay G30 / G60 Generator Protection Relay D30 / D60 Line Distance Protection Relay C70 Capacitor Bank Protection Relay
Auxiliary Expansion Modules
UR6DH Digital Input / Output Module UR7BH Communication Expansion Module UR8NV RTD Temperature Acquisition Module
Supporting Software Tools
EnerVista UR Setup – Configuration & Commissioning Software EnerVista Viewer – Fault Recorder Analysis Software
Auxiliary Materials
Standard UR series chassis Ring-type crimp cable lugs Conductive cleaner for backplane contact cleaning Shorting & grounding links for transformer secondary circuits
FAQ
Q1 How to verify compatibility of existing protective relays with UR8LH before procurement?
A1 Two checks are required: First, check the internal CPU model of the relay, which must be new-generation models starting with digit 9 including 9E/9G/9H/9J/9K. Second, confirm the firmware version of the relay. Versions V4.0 and above offer native compatibility; units running firmware lower than V4.0 shall purchase a firmware upgrade kit together.
Q2 Can UR8LH directly replace legacy CT/VT modules without diagnostic functions?
A2 It features identical physical slot dimensions for plug-and-play replacement. However, after replacement, users must re-identify hardware and reconfigure transformer parameters via EnerVista software, as well as upgrade firmware to activate diagnostic functions. Otherwise, persistent hardware mismatch alarms will be triggered.
Q3 The relay displays "CT/VT Module Fault" alarm during operation while field wiring is intact, how to troubleshoot?
A3 Step 1: Power off the unit, remove the module and wipe off oxidation on backplane gold fingers. Step 2: Reinstall the module smoothly and fasten fixing screws tightly. Step 3: Power on and check self-test status. If the alarm clears, the root cause is poor contact. If the alarm remains, the module hardware is defective and replacement is required.
Q4 The on-site CT is rated 5A, yet readings in software are only 20% of actual values. What is the root cause?
A4 The hardware DIP switch on top of the module is mistakenly set to the 1A position, leading to mismatch between hardware sampling gain and software transformation ratio parameters. Power off the unit, switch the DIP to the 5A position, reboot the device and recalibrate sampling readings to restore normal operation.
Q5 A single CT channel continuously reports open-circuit alarm, while multimeter testing shows continuity on the transformer secondary circuit. How to resolve this?
A5 Inspect two aspects: 1) Loose wiring or oxidized poor contact at rear module terminals; 2) Hidden breakpoints inside the CT secondary circuit, which conducts under heavy current yet disconnects under light current. Disassemble cables section by section and perform segmented measurement.
Q6 When expanding with multiple UR8LH modules in one chassis, is there a maximum channel limit?
A6 Limits depend on UR chassis slot specifications: A 6-slot chassis supports up to 2 pieces of UR8LH, while a 12-slot chassis accommodates a maximum of 4 pieces. Installation beyond the slot limit is impossible, and total available channels are restricted by physical chassis slots.
Q7 Can UR8LH work with 110V VT transformers for overseas projects?
A7 The module hardware only supports two standard VT secondary input ratings: 100V and 220V. 110V VT cannot be directly connected. A step-down isolation transformer shall be installed on the VT secondary side to convert voltage to the standard 100V level.
Q8 What storage requirements apply to spare UR8LH modules for long-term stocking?
A8 Storage temperature shall be maintained between -40℃ and +85℃, with relative humidity below 80% and no condensation. Modules shall be packed in original anti-static packaging and kept away from strong magnetic fields and high-voltage switchgear. If storage duration exceeds 2 years, conduct a full 2-hour power-on self-test before commissioning.
Recommended UR Series Models
- UR8LH: 4CT/4VT Acquisition Module with Enhanced Diagnostics
- URRLH: High-Density 8CT/8VT Module
- UR8FV: Cost-Effective Basic 4CT/4VT Acquisition Module
- UR8GH: High-Precision Metering CT/VT Acquisition Module
- UR8MH: CT/VT Module Dedicated to Ground Fault Detection
- UR6DH: 16-Channel Digital Input & Output Module
- UR7BH: Multi-Protocol Communication Expansion Module
- UR8NV: RTD Temperature Analog Acquisition Module
- UR9EH: UR Series Main Control CPU Module
- UR9GH: High-Performance Computing CPU Module
- UR9HH: CPU Module for Redundant Protection Applications
- UR6FH: Fast Trip Digital Output Module
- UR6D: 32-Channel High-Density DI/DO Module
- UR8LV: Low-Temperature CT/VT Acquisition Module
- UR9GV: CPU Module with Gigabit Ethernet Port
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