GE Multilin UR-8HH UR Series CT/VT Module

Description

The GE Multilin UR-8HH is an engineering-grade analog input module designed for the UR Series protection relay platform. Engineered to process critical alternating current signals, the UR-8HH function delivers a dedicated high-density Standard 8CT configuration that manages eight current transformer inputs on a single slot card. It operates by interfacing directly with primary power system lines via external current transformers, providing comprehensive current measurement coverage across multiple zones or parallel three-phase circuits without requiring auxiliary intermediate CT components. By supporting versatile, software-configurable 1A / 5A ground current transformer settings, the module enables precision ground and phase fault monitoring across diverse low-voltage, medium-voltage, and high-voltage electrical substation operations. This module communicates directly via the system internal bus to feed raw high-speed digitized analog samples to the primary CPU processor, supporting advanced protection elements, true RMS metering, oscillography capture, and detailed current harmonic tracking.

Features

• Provides a compact high-density hardware architecture housing 8 Current Transformer (8CT) analog inputs within one full-height rack slot.
• Features dual-rated secondary compatibility supporting both 1 A and 5 A standard current transformer secondary loops.
• Implements direct high-speed analog-to-digital signal processing feeding synchronous samples into the relay internal calculation path.
• Eliminates the need for external auxiliary current transformers through software-adjustable internal scale matching.
• Integrates automatic mechanical shorting mechanisms across the external CT circuitry to guarantee technician safety during module withdrawal sequences.
• Designed with distinctive blue identification labels and explicit safety warning markers to prevent system mismatching with legacy CPU architectures.

Applications

• Multi-winding transformer differential protection configurations within utility substations.
• High-density current monitoring for ring-bus configurations and breaker-and-a-half power distribution schemes.
• Comprehensive ground fault, neutral current tracking, and phase-overcurrent monitoring networks.
• Raw current waveform capture and high-resolution dynamic oscillography logging for power system diagnostic applications.

Technical Specifications

Connections/Interfaces

The rear terminal layout of the UR Series uses a structured three-character coordinate identification code assigned based on the selected slot housing the UR-8HH card.

• Current Transformer Screw Terminals: High-torque block headers equipped with dedicated underlying shorting bars designed to safely route continuous AC current loop configurations.
• Dedicated Channel Mapping: Pin configurations split across eight distinct current input channels, each accepting dual phase-polarity (Inlet / Outlet) instrumentation paths.

Installation Guidelines

• Power Precaution: Complete system control power must be physically disconnected and isolated from the main relay chassis prior to initiating any module insertion or withdrawal tasks.
• Hardware Cohesiveness: The UR-8HH belongs to the modern generation of UR components. It must only be paired with a CPU module designated with code 9E or higher. Mixing this card with legacy CPU modules (e.g., 9A, 9C, 9D) will result in a fatal DSP ERROR or HARDWARE MISMATCH state.
• Electrostatic Grounding: Technicians are strictly required to employ fully grounded anti-static wrist straps during handling to guard internal circuit layers against ESD stress.
• Seating and Locking: Fully open the wide-angle hinge faceplate, align the card with the tracking slot, slide smoothly inside until the outer frame clears the lip, and then engage both top and bottom ejector/inserter clips simultaneously to fully lock the internal backplane connection.