The GE Multilin UR4DH is a high-density digital input/output expansion module dedicated to the GE Vernova UR universal relay series. Originally engineered to pair with UR series protection and control main units for expanding field discrete signal channels, it serves as the standard I/O expansion unit for power protection systems in substations, generator sets, oil, gas and chemical facilities.
This module integrates 8 configurable digital inputs and 4 isolated Form‑C relay outputs. It connects directly to the processor via the UR backplane, enabling microsecond-level signal transmission without additional couplers. It handles field signal exchange tasks including circuit breaker position feedback, disconnector status acquisition, alarm contact monitoring, and closing/tripping logic output.
Designed for harsh industrial electromagnetic environments, it supports flexible capacity expansion based on the unified modular architecture of the UR platform, and is widely deployed for protection and control applications supporting primary power equipment.
Product Advantages
- Compact high-density channel layout with 8DI+4DO per unit, saving backplane slots and cutting hardware & spare parts inventory costs
- 2500Vrms reinforced isolation between all channels and backplane logic, eliminating ground loop interference and high-low voltage crosstalk
- Native backplane communication bus with signal latency under 10ms, meeting fast grid protection requirements for interlock and emergency shutdown logic
- Wide industrial temperature range from -40℃ to +70℃ for continuous operation, suitable for outdoor kiosks, offshore platforms and high-temperature electrical rooms
- Hot-swap design enables online replacement without powering off the whole protection relay, drastically reducing maintenance downtime
- Fully software-configurable parameters: digital inputs support 24-250VDC adaptive voltage, relay contacts rated 10A resistive load for most auxiliary field circuits
- Complete self-diagnosis function detecting open wiring, contact adhesion and communication faults, uploading real-time alarms for rapid on-site troubleshooting
- Full firmware compatibility with all UR series relays, supporting IEC61850, Modbus and GOOSE protocol synchronization for seamless substation automation integration
Model Decoding
UR 4DH consists of three fixed character segments defined by official GE specification, no suffix variants for hardware revisionsUR: Abbreviation of Universal Relay, unified prefix for all Multilin protection relays and expansion modules4: Output channel code, representing 4 Form-C SPDT electromagnetic relay outputsDH: Digital High-density, identifier for high-density digital I/O hardware equipped with 8 isolated digital inputsUR-4DH is the alternative part number used in spare part lists and order documents, fully interchangeable with UR 4DH without functional or mechanical differences
Product Specifications & Features
Hardware Channel Layout8 digital inputs supporting dry contact or 24-250VDC active voltage signals, max 5mA input current per channel, channel scanning cycle less than 10ms4 Form-C single-pole double-throw relay outputs, contact rating 10A@250VAC / 10A@30VDC resistive load for trip, close and alarm signal drivingElectrical Safety Standards2500Vrms isolation rating between each channel and backplane, independent isolation per channel to prevent signal crosstalk; UL certified for industrial safetyEnvironmental PerformanceOperating temperature: -40℃ ~ +70℃, storage temperature: -40℃ ~ +85℃, humidity 5%-95% non-condensing, resistant to dust and vibration in industrial sitesCommunication & Logic FunctionsHigh-speed parallel backplane bus direct connection with UR CPU, no gateway required; FlexLogic programmable logic for custom interlock schemesReal-time full-channel diagnostics, recording event timestamps for channel state changes and faults for post-failure analysisMechanical StructureStandard UR backplane slot dimension, hot-swappable slide rail mounting; metal shielding shell to suppress external electromagnetic radiation; modular terminal blocks for convenient field wiring modification
Application Industries
Power Transmission & DistributionI/O expansion for feeder, busbar and transformer protection panels in substations, collecting status signals of circuit breakers, earthing switches and disconnectors, outputting fault trip and annunciator alarm signalsPower GenerationProtection systems for thermal, hydro and gas turbine generators, monitoring auxiliary equipment contacts and executing unit interlock shutdown logicOil & Chemical IndustryComprehensive power protection for refineries and offshore drilling platforms, signal collection & control for high-voltage motors and compressors, supporting ESD emergency shutdown systemsMining & MetallurgyHigh-voltage power distribution and furnace transformer protection for large mines, interlock control and fault alarm expansion for heavy-duty motorsWater Treatment PlantsHigh-voltage motor protection and power room monitoring for pump stations, remote close/trip control for water pumps and valvesRailway Traction Power Supply
Signal expansion for traction substation protection relays, monitoring switchgear and DC panel alarm contacts
FAQ
Q1: Can UR4DH work independently without UR protection relay host?A1: No. UR4DH has no independent processor or power supply circuit, it only acts as backplane expansion card and must be installed into UR relay to function.
Q2: Does UR4DH digital input support 220VAC AC signal collection?A2: Official specification only supports 24-250VDC DC input. AC signals require external intermediate relays to convert into DC dry contacts before connecting to the module.
Q3: Can relay outputs of UR4DH directly drive HV circuit breaker trip/close coils?A3: Not allowed. Contact rating is only 10A resistive load, breaker coils are high-power inductive loads; external high-capacity intermediate relays are required for signal transfer.
Q4: Are UR4DH and UR-4DH identical and interchangeable?A4: They are the exact same hardware unit, only different writing formats. No differences in channel layout, firmware compatibility or mounting size, direct field replacement is available.
Q5: Frequent open-circuit alarms on module channels, what are troubleshooting steps?A5: Inspect damaged secondary cables, loose terminal wiring, oxidized external contacts, insufficient input loop voltage and overly small anti-jitter parameters in software sequentially.
Q6: UR4DH supports hot-swap, will plugging/unplugging trigger accidental protection trips?A6: Official hardware integrates surge suppression circuits, standardized hot-swap operation will not trigger false output logic. Do not touch metal terminal contacts during replacement to avoid short circuits.
Q7: What is the maximum number of UR4DH modules installable on one UR relay host?A7: Depends on backplane slot quantity. Standard 8-slot UR host supports up to 6 I/O expansion modules, reserving 2 slots for communication and analog modules.
Q8: Is UR4DH end-of-life? What is the standard delivery lead time?A8: This module remains in GE Vernova standard supply list. Spot goods deliver within 3-7 working days, bulk overseas orders take 15-30 working days.
3005319639