Key Technical Specifications
- Product Model: UR8LH
CT/VT module providing 4 current and 4 voltage analog inputs. - Manufacturer: GE Multilin
Original equipment for UR series protection and control relays. - Module Type: CT/VT Analog Input Module
Scales high-voltage/current signals to relay-processable levels. - Channel Configuration: 4 CT + 4 VT Inputs
Supports three-phase measurement plus neutral/residual. - Input Voltage Range: 100 V to 1500 V
Wide range accommodates various VT secondary ratings. - Measurement Accuracy: ±0.5% Typical
Meets protection-class accuracy requirements. - Response Time: 10 ms Typical Time Constant
Fast response for fault detection and protection tripping. - Diagnostic Feature: Enhanced Signal Integrity Verification
Advanced algorithms validate analog signal health continuously. - Redundancy: Dual Module Configuration Supported
Two UR8LH modules can provide backup for critical applications. - Data Access: Front Panel LCD / EnerVista UR Software
Real-time viewing of measured values and diagnostics. - Installation: Plug-in Module for UR Relay Chassis
Hot-swappable capability for reduced downtime. - Weight: 2 kg (4.4 lbs)
Verify rack mechanical support for multi-module configurations.
Product Introduction
GE UR8LH is a CT/VT analog input module for the GE Multilin UR series universal relays. It provides four current transformer and four voltage transformer inputs, scaling primary power system signals to levels the relay processor can measure and analyze for protection and control functions.This module’s key differentiator is its enhanced diagnostic capability, which uses advanced algorithms to continuously verify analog signal integrity. With ±0.5% typical accuracy and a 10 ms response time, the UR8LH ensures reliable fault detection. (I’ve seen CT open-circuit conditions go undetected on older modules until a fault occurred; the UR8LH’s diagnostics catch these before they become protection failures.)
Installation & Configuration Guide
Preparation (10 min)
Verify the UR relay chassis has an available module slot. Review the single-line diagram to confirm CT/VT ratios and polarity markings. Have the EnerVista UR Setup software ready with the correct relay settings file. Ensure appropriate PPE for working near energized CT/VT circuits.Removal (5–10 min)
If replacing an existing module, verify the relay is in maintenance mode. Open the hinged front panel. Loosen the captive screws and pull the module straight out. CRITICAL: Verify all CT secondary circuits are shorted before disconnecting wiring. Open CT secondaries can produce lethal voltages. Label all wires before disconnection.Installation (10 min)
Align the UR8LH with the backplane connector and slide in firmly until seated. Tighten captive screws. Reconnect CT and VT wiring per the relay’s wiring diagram; double-check polarity markings (H1/X1, H2/X2). Verify CT shorting blocks are properly configured. Torque all terminals to specification.Power-On & Test (10 min)
Restore power to the UR relay. Verify the relay recognizes the UR8LH module. Check measured voltage and current values against known references (e.g., meter readings). Verify phase rotation and polarity indicators. Review the enhanced diagnostics screen for any signal integrity warnings. Confirm all 8 channels display valid measurements.
Troubleshooting Quick Reference
| Symptom | Probable Cause | Immediate Check |
|---|---|---|
| Module Not Recognized | Backplane connection issue | Reseat module; inspect backplane pins for damage. |
| Zero Current Reading | Open CT circuit or wrong ratio | VERIFY CT SHORTS FIRST; check ratio setting in config. |
| Erratic Voltage Readings | Loose VT connection or noise | Check VT terminal torque; verify shielding and grounding. |
| Diagnostic Alarm Active | Signal integrity failure | Review diagnostic details; check for CT saturation or wiring fault. |
| Phase Rotation Error | Polarity reversal | Verify H1/H2 and X1/X2 markings match single-line diagram. |
| All Channels Invalid | Module or backplane failure | Try module in different slot; test with known-good module. |
Dimensions, Mounting & Wiring Notes
- Form Factor: Plug-in module for UR relay chassis
- Mounting: Internal module bay; accessible via hinged front panel
- Wiring: CT/VT connections via screw terminals; use shielded cable for VT inputs
- Weight: 2 kg (4.4 lbs)
- Terminal Torque: Follow GE UR relay installation manual for specified torque values
- CT Safety: Always install CT shorting blocks before disconnecting; verify shorts before energizing
- Clearance: Maintain minimum clearance per UR relay chassis specifications for airflow and wire bend radius
FAQ
What does “enhanced diagnostics” actually do?
The UR8LH continuously monitors analog signal integrity using advanced algorithms. It can detect CT open circuits, VT fuse failures, signal saturation, and wiring errors before they cause protection misoperation. Think of it as a built-in test set that never stops running.Can I hot-swap this module?
Yes, the UR8LH supports hot-swap capability. However, always verify CT secondary circuits are shorted before removal. Even though the module can be replaced while energized, the CT circuits themselves must be protected. Plan for a brief maintenance window when possible.How do I verify CT/VT ratios are correct?
Use the EnerVista UR Setup software or front-panel HMI to view the configured ratios. Compare against the nameplate ratings on the actual CTs and VTs. A common mistake: configuring 1200:5 CT ratio when the actual CT is 600:5. This causes all current measurements to be off by 2x.I’m seeing a diagnostic alarm, what now?
First, check the diagnostic detail screen to identify which channel is affected. For CT alarms, verify the secondary circuit is intact and not open. For VT alarms, check fuses and connections. If the alarm persists with verified good wiring, try swapping to a known-good module to isolate the fault.Can I use this for metering applications?
The UR8LH provides ±0.5% typical accuracy, which is suitable for protection and general monitoring. For revenue-grade metering requiring ±0.2% or better, verify your utility’s requirements. The module’s accuracy is adequate for most industrial and substation applications.What’s the difference between UR8LH and UR8L?
The UR8LH includes enhanced diagnostic capabilities that the standard UR8L lacks. If your application requires continuous signal integrity monitoring or you’re upgrading an older UR relay, the UR8LH provides additional protection against undetected measurement failures.Do I need special tools for CT wiring?
Standard screwdrivers and a torque driver are sufficient. However, always use properly rated CT shorting blocks and test switches. Never use makeshift jumpers or alligator clips on CT secondaries. The risk of open-circuit CT voltage is not worth saving a few dollars on proper test equipment.
