Description
Key Technical Specifications
- Product Model: UR8NH
- Manufacturer: GE Multilin
- Product Type: CT/VT Input Module
- System Compatibility: GE UR Series Universal Relays
- Channel Count: 8 Standard CT Inputs
- Current Rating: 1A / 5A Selectable
- Diagnostic Feature: Advanced Hardware Health Monitoring
- Configuration Software: EnerVista UR Setup
- Mounting Style: Backplane Plug-in Module
- Environmental Rating: IP20 (Internal Relay Mounting)
Product Introduction
If your UR relay is seeing ghosts or tripping on load, the problem usually isn’t the logic—it’s the front end. The GE UR8NH is the standard 8-channel CT/VT module that translates raw, dangerous power signals into clean digital data the relay can trust. I’ve seen too many “bad relays” that were actually just tired input modules drifting out of spec after years of thermal cycling. The UR8NH is the workhorse that keeps the measurement foundation solid so the protection algorithms can actually do their job.
Engineers stick with the UR8NH because it’s not just a passive transformer; it’s got active diagnostics built in. It constantly monitors its own health and the CT/VT circuit integrity, flagging issues before they cause a misoperation. One subjective note: this module runs warm. The UR8NH dissipates real power internally, so don’t bury it in a sealed, unventilated relay chassis. I’ve seen these cook themselves to death in poorly designed panels; give it some airflow, and it’ll outlast the equipment it’s protecting.
Quality SOP & Tech Pitfalls
We don’t ship blind. Every GE UR8NH gets a visual inspection for cracked housings or bent backplane pins before it even touches a test bench. Then it goes on a live UR test rack where we inject known secondary currents and verify the scaling matches the EnerVista UR readout. I use a Fluke 115 to check isolation resistance and ensure there’s no leakage path that could compromise safety or accuracy. Firmware versions are logged, and the unit is sealed in anti-static packaging.
Here is where people mess up: they ignore the diagnostic alarms. The will tell you if a CT circuit is open or if the internal reference is drifting, but only if you’re actually looking at the event log. I once saw a plant ignore a “CT/VT Health” warning for months, only to have the module fail completely during a minor line fault, causing a cascading outage. Also, never open a CT secondary while the primary is energized. It’s a fast track to an arc flash or a destroyed . Always verify your jumper settings against the OEM manual before applying power.
Installation & Configuration Guide
- Pre-Installation: ⚠️ SAFETY FIRST. Ensure the primary power is completely de-energized and locked out. Verify that all CT secondary circuits are shorted before disconnecting the old module to prevent open-circuit voltage spikes. Photograph the existing wiring and jumper block settings.
- Removal: Label every wire meticulously. Release the backplane locking mechanism and pull the straight out. Inspect the backplane receptacle for any bent or corroded pins.
- Installation: COPY ALL JUMPER SETTINGS NOW. This step prevents 90% of startup failures. Align the new with the backplane guides and press firmly until the locking mechanism engages. Reconnect the wiring exactly as photographed, ensuring CT grounds are intact.
- Power-On & Testing: Restore control power. Open EnerVista UR and verify that the module is recognized. Inject a low-level test current and verify that the relay’s measured values match your test set. Check for any CT/VT wiring alarms in the event log.
GE UR8NH
Compatible Replacement Models
- ✅ Drop-in Replacement: (Ensure the suffix matches exactly; GE occasionally updates internal components without changing the base model number).
- ⚠️ Software Compatible: -RevC (Same physical footprint, but requires a firmware update in the main relay chassis; expect 15 minutes of configuration time).
- ❌ Hardware Mod Required: UR7NH (Older generation with different backplane pinout; do not attempt to force this into a slot without replacing the entire relay chassis).
Frequently Asked Questions
Can I hot-swap this module while the relay is powered?
No. Pulling the while the relay is live will cause an immediate loss of measurement data, which will trigger a “CT/VT Fail” alarm and likely cause the relay to trip the breaker. Always schedule this swap during a planned outage or maintenance window.
The relay is showing a “CT Open” alarm. Is the module bad?
Before condemning the , check your field wiring. A loose terminal screw or a broken wire in the junction box will cause this exact alarm. I’ve seen techs swap three “bad” modules before realizing there was a corroded connection in the field. Measure the CT loop resistance with a multimeter first.
Do I need to recalibrate this in the field?
No. The is factory-calibrated and sealed. There are no internal adjustment pots. If the relay is reading incorrectly, verify your CT ratio settings in EnerVista UR. If the settings are correct and the reading is still wrong, replace the module.
Is this compatible with all UR series relays?
Generally, yes, but always verify the specific relay model (e.g., UR-8, UR-6) and firmware revision. The is designed for the UR platform, but mixing very old relay firmware with newer input modules can sometimes cause communication issues. Check the GE Multilin compatibility matrix before installing.
What happens if the secondary ground is lost?
If the secondary ground on the is lost, the module will still function under normal conditions, but during a primary fault, the secondary voltage can float to dangerous levels. This poses a severe shock hazard and can destroy the module. Always verify the ground connection during installation and during annual maintenance.
Does this come with a warranty?
Yes, every we ship has a 1-Year Warranty. We test these because a failed input module can lead to a misoperation of the protection system. If it fails, we replace it. No arguments.
