The GE Multilin UR‑8HH is an 8-channel CT/VT (current/voltage transformer) input module designed for the UR Series universal relays.It is primarily intended to provide high-precision, high-reliability current and voltage signal acquisition and conversion for power system protection, control, and metering applications.
It integrates 3 phases of phase current CT inputs, 1 earth fault CT input, and 4 voltage VT inputs, supporting connection to standard 1A/5A current transformers and conventional voltage transformers.The module converts high-voltage and high-current primary-side signals into proportional low-level signals processable by the relay, serving as the core signal acquisition unit for the UR Series relays to implement protection, fault monitoring, and energy metering for power equipment such as power lines, transformers, and busbars.Featuring a modular, plug-and-play design, the UR‑8HH is fully compatible across the entire UR Series platform.It is suitable for complex power applications including substations, industrial power distribution, and power generation, fulfilling key requirements such as high-sensitivity earth fault detection, high-accuracy metering, and high-speed fault recording.
Technical Specifications
1. General Information
Manufacturer: GE Multilin (a brand under GE Vernova)Product Series: UR Series Universal RelaysModule Type: CT/VT Signal Acquisition ModuleWeight: Approximately 2.55 lbs (1.16 kg)Place of Manufacture: Markham, Ontario, CanadaConfiguration Software: EnerVista UROperating Temperature: -40°C ～ +85°CCertifications: UL, CE, CSA and other industrial and power industry standards
2. Input Channel Configuration
The module is equipped with three channels of phase current CT inputs, which are configurable for 1A or 5A rated inputs and compatible with standard phase current transformers. These channels are used to acquire three-phase A/B/C currents for overcurrent, instantaneous trip, differential and other protection functions.
It also provides one channel of ground current CT input, configurable for 1A or 5A, suitable for zero-sequence or ground current transformers. This channel enables high-sensitivity ground fault detection and supports small-current ground fault monitoring.
In addition, the module includes four channels of voltage VT inputs designed for the secondary side of standard voltage transformers, typically 100V, to acquire line or phase voltages for overvoltage, undervoltage, frequency and power metering functions.
With a total of eight input channels, the module supports synchronous acquisition of three-phase current, ground current and multi-channel voltage signals.
3. Performance Parameters
Measurement Accuracy: Current and voltage measurement accuracy ≤ ±0.2%, compliant with IEC power metering standards.Sampling Rate: Supports up to 64 samples per cycle to meet the high-speed fault recording requirements of UR relays.Response Time: Signal conversion and transmission delay < 1ms to ensure fast protection operation.Isolation Characteristics: Electrical isolation between input channels and between channels and the system, with withstand voltage ≥ 2.5kV and strong electromagnetic interference immunity.Temperature Drift: Typical temperature drift ≤ 25ppm/K, ensuring excellent measurement stability in wide-temperature environments.
Core Functions
1. High-Precision Signal Acquisition and Conversion
The module performs isolation, step-down, current reduction and linear conversion on primary-side current and voltage signals, and outputs analog signals suitable for the UR relay CPU, providing accurate data sources for protection logic and metering algorithms.It supports flexible configuration of 1A/5A current inputs, is compatible with CTs of various ratios, and adapts to power systems of different voltage levels.
2. High-Sensitivity Ground Fault Protection
The dedicated ground CT channel, combined with UR relay protection algorithms, enables accurate detection of small-current ground faults with much higher sensitivity than conventional phase current channels, effectively capturing latent ground faults in distribution networks and auxiliary power systems.It supports ground fault direction identification, fault recording and event logging, providing a basis for fault location and troubleshooting.
3. Comprehensive Power Metering Support
By synchronously acquiring three-phase current and voltage signals, it supplies data to the built-in metering functions of UR relays, calculating active power, reactive power, apparent power, power factor, frequency, electric energy and other parameters to meet power system operation monitoring and energy settlement requirements.
4. Fault Recording and Event Logging
Working with UR relays, it captures full-time waveform records before, during and after faults, supporting synchronous recording of 64 digital channels and 40 analog channels with a maximum recording duration of 45 seconds, providing complete data for fault analysis and relay protection operation verification.It supports Sequence of Events (SOE) logging with a timestamp accuracy ≤ 0.5ms and can store up to 1024 events, facilitating traceability of system operation and fault sequences.
5. Modularity and Scalability
The plug-in design supports hot-swapping on selected UR models, allowing convenient installation, maintenance and replacement without affecting overall system operation.A single UR relay can be equipped with multiple UR‑8HH modules to meet signal acquisition requirements for multiple bays and circuits, suitable for complex substations and industrial power distribution systems.
Typical Applications
1. Electric Power Substations
Applied to protection for lines, transformers and busbars in substations of 110kV and below, providing current and voltage acquisition and ground fault monitoring, and implementing integrated protection and control with UR series relays.It serves as a front-end signal acquisition unit for substation automation systems, supplying real-time operating data to SCADA systems.
2. Industrial Power Systems
Used in auxiliary power systems of large industrial enterprises such as metallurgy, petrochemical and mining, protecting key equipment including high-voltage motors, frequency converters and rectifiers, monitoring load current, voltage and ground faults to ensure continuous and stable industrial production.
3. Power Generation Systems
Deployed in auxiliary power and step-up stations of thermal, hydro and new energy power plants, acquiring current and voltage signals at generator outlets, main transformers and auxiliary transformers to realize fault protection and operation monitoring for generating units and auxiliary power systems.
4. Distribution Network Automation
Suitable for distribution switching stations and ring main units, providing overcurrent and ground fault protection for distribution lines, supporting rapid fault location and isolation to improve distribution network power supply reliability.
Product Advantages
High-reliability industrial-grade design: wide temperature range, high isolation and strong anti-interference performance, adapting to the harsh electromagnetic environment of power systems with stable long-term operation.High-precision measurement: metering-class accuracy that meets dual requirements of power system protection and metering, reducing the impact of measurement errors on protection operations and energy settlement.High integration: one module integrates 8 channels of CT/VT inputs, simplifying system wiring and lowering installation and maintenance costs.Strong platform compatibility: fully compatible with all models of UR series relays, and can be flexibly combined with digital I/O, communication, CPU and other modules to build customized protection and control systems.Easy configuration and commissioning: channel configuration, parameter calibration and fault recording analysis via EnerVista UR software, supporting remote commissioning and status monitoring.
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