Description
Hard-Numbers: Technical Specifications
- CT Channel Count: 8 isolated current inputs (expandable 3-phase + multi-winding)
- VT Channel Count: 4 isolated AC voltage sensing inputs
- CT Nominal Rating: Software selectable 1A / 5A secondary
- VT Nominal Rating: Software selectable 67V / 120V
- Operating Temperature: -40°C to +70°C ambient cabinet rating
- Isolation Rating: 2500Vrms reinforced isolation, field to backplane
- Maximum Power Draw: 8.2 Watts, backplane supplied
- Sample Resolution: 16-bit high-resolution ADC per analog channel
- Hot-Swap Capability: Live insert/remove with automatic CT shorting logic
- Measurement Accuracy: 0.2% full scale for precision metering applications
UR8FH
The Real-World Problem It Solves
Standard 4CT modules force techs to daisy-chain external panels for multi-winding transformers or bus zones. Extra wiring adds points of failure and increases calibration time.
Where you’ll typically find it:
- Multi-winding transformer bays (2/3/4-winding) at transmission substations
- High-density bus differential protection schemes in large switchyards
- Industrial plant main switchgear with multiple parallel feeder CTs
Bottom line: It eliminates external CT expansion panels, cutting wiring complexity and improving data synchronization for complex protection zones.
Hardware Architecture & Under-the-Hood Logic
UR-8LA uses a dedicated analog signal processor and 8 independent CT front-ends, all galvanically isolated from the UR backplane. No shared multiplexer—each channel has its own anti-aliasing filter.
- 8 CT and 4 VT secondary signals enter individual surge suppression and limiting circuits.
- Each CT channel uses a precision burden resistor and programmable gain stage.
- 12 dedicated 16-bit ADCs convert analog signals to digital samples simultaneously.
- Local DSP filters noise, checks for CT saturation, and flags open/shorted inputs.
- Time-aligned, fault-checked data transfers across isolated backplane to host relay.
- Onboard non-volatile memory stores channel calibration data for hot-swap consistency.
UR8FH
Field Service Pitfalls: What Rookies Get Wrong
Overlooking CT Shorting Blocks During InstallationNew techs skip shorting the CT secondary before inserting the module. Live CTs open-circuit, inducing thousands of volts and damaging the module and connected equipment.
- Field Rule: Always short all CT terminals at the panel block before inserting/removing the module; remove shorts only after all wiring is secured.
Mismatched CT Ratios Across 8 ChannelsTechs mix 1A and 5A CT secondaries on the same module. Mismatched ratios create unbalanced differential currents and false trips.
- Field Rule: Configure all 8 CT channels for the same nominal rating (1A or 5A) in firmware; label all wiring clearly to avoid cross-connection.
Ignoring Heat Buildup in Dense RacksStacking multiple high-density analog modules (UR-8LA/8HH) in adjacent slots traps heat. Sustained high temps cause ADC drift and premature failure.
- Quick Fix: Leave one empty slot between high-density analog modules; maintain cabinet airflow >100 CFM and clean filters quarterly.
Commercial Availability & Pricing Note
Please note: The listed price is for reference only and is not binding. Final pricing and terms are subject to negotiation based on current market conditions and availability.
