GE UR Series RHH Modules GE UR RHH Universal Relay Digital I/O Module

Technical Dossier

Product Details And Specifications

GE UR Series Technical Notes

The Evolution of UR Series Architecture

The UR platform was introduced in the late 1990s as a successor to GE Multilin's SR Series relays, consolidating protection, metering, control, and communications into a single modular chassis. Early UR hardware (firmware generation 1.x–3.x) used proprietary backplane communication and supported RS-485 serial interfaces (DNP3, Modbus RTU). The mid-generation transition (firmware 4.x–5.x) introduced IEC 61850 GOOSE messaging via the 9E Ethernet module and expanded the I/O module count per chassis. Current-generation UR hardware (firmware 7.x) supports IEEE 1588 precision time protocol, redundant Ethernet, and cybersecurity hardening per NERC CIP standards.

Compatibility constraints are a persistent operational challenge: early-generation CPU modules (9G5, 9G6) are not firmware-compatible with later-generation I/O modules without a full chassis upgrade. The RHH Digital I/O module is compatible across mid-to-late UR generations but requires verification of backplane revision before substitution. Engineers maintaining mixed-generation fleets must cross-reference the UR Order Code matrix published in GE document GEK-113000.

UR Series Full Catalog & Functionalities (SKU List)

CPU / Main Processing Modules

• 9G5: Early-generation CPU module; supports DNP3/Modbus serial; no IEC 61850 native support.
• 9G6: Mid-generation CPU; adds IEC 61850 GOOSE; compatible with UR firmware 4.x–5.x chassis.
• 9G7: Current-generation CPU; IEEE 1588 PTP; NERC CIP cybersecurity hardening; dual Ethernet ports.

Digital I/O Modules

• RHH: Universal Relay Digital I/O Module; 8 contact inputs, 8 output relays; hardwired trip/alarm/interlock circuits.
• RHA: Digital I/O module variant; 16 contact inputs; optimized for high-density input applications.
• RHB: Digital I/O module; 8 inputs / 4 high-current output contacts; rated for motor control applications.
• RHC: Digital I/O module; 4 fast-operate output contacts; <8 ms operate time for high-speed trip circuits.
• RHD: Digital I/O module; mixed I/O; 6 inputs / 6 outputs; general-purpose protection relay applications.

Analog I/O Modules

• 9A1: AC analog input module; 4 current / 4 voltage channels; 16-bit ADC; for current differential protection.
• 9A2: AC analog input module; 8 current channels; bus differential and transformer protection applications.
• 9A3: DC analog input module; 4–20 mA / 0–10 V inputs; process variable monitoring integration.

Communications Modules

• 9E: Ethernet communications module; 10/100 Base-T; IEC 61850 Ed.1/Ed.2; DNP3 over TCP/IP.
• 9E2: Dual-port Ethernet module; redundant network topology support; RSTP/PRP/HSR protocols.
• 9F: Fiber-optic communications module; ST connector; inter-relay direct fiber channel for POTT/PUTT schemes.
• 9S: Serial communications module; RS-232/RS-485; Modbus RTU / DNP3 serial for legacy SCADA integration.

Power Supply Modules

• 9P1: DC power supply module; 24–48 VDC input; for substation battery-backed DC bus applications.
• 9P2: DC power supply module; 110–250 VDC / 100–240 VAC universal input; standard substation supply.
• 9P3: Redundant power supply module; dual-feed input; hot-swap capable; for critical continuous-operation sites.

Transducer / Specialty Modules

• 9T1: Transducer input module; RTD / thermocouple inputs; transformer thermal overload protection.
• 9T2: Transducer output module; 4–20 mA analog outputs; metering retransmission to DCS/SCADA.