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Key Technical Specifications
| Parameter | Specification |
|---|---|
| Product family | GE Multilin UR series CT/VT module |
| Phase CT inputs | Multiple phase CT channels |
| Ground CT input | Ground CT channel |
| VT inputs | Multiple voltage transformer channels |
| CT accuracy | Verify with OEM datasheet |
| VT accuracy | Verify with OEM datasheet |
| CT/VT burden | Per-channel VA rating; confirm on nameplate |
| Mounting | Installed inside GE Multilin UR relay chassis |
| Configuration | EnerVista UR software |
| Typical applications | Feeder, transformer, generator, bus, and motor protection schemes |
| Environment | Industrial operating temperature range; confirm exact limits per datasheet |
| Compatibility | Must match UR relay CPU, firmware revision, and chassis slot configuration |
Product Introduction
UR8AH is the kind of module you only notice when it is missing. It lives inside a GE Multilin UR relay and does the unglamorous but critical job of bringing CT and VT signals into the protection platform. No analog inputs, no metering, no overcurrent or voltage protection. Simple as that.I have seen plants order a “UR relay” without checking whether the CT/VT module is installed. The CPU boots, the HMI lights up, and then the protection engineer realizes there is nothing reading the feeder current. UR8AH fixes that. It provides phase CT channels, a ground CT channel, and multiple VT channels inside the UR chassis. The real catch is firmware. Older UR relays running legacy firmware may not accept newer CT/VT modules without a CPU firmware update, so always confirm the CPU revision and installed module set before committing to a purchase.
Quality SOP & Tech Pitfalls
The Lab Report (SOP)
- Visual and counterfeit check: verify UR8AH label, GE Multilin branding, serial number, PCB condition, and connector pins.
- Chassis compatibility check: confirm the module matches the UR relay chassis generation and CPU firmware level.
- Live test on UR test rack: install into a compatible UR relay, verify module recognition in EnerVista, and confirm CT/VT channel presence.
- Meter checks: verify CT/VT terminal continuity, insulation resistance, and absence of shorted or open analog channels using a Fluke 115 or equivalent.
- Final seal: anti-static bag, desiccant, reinforced carton, and photos of nameplate, test screen, and installed module.
The Engineer’s Warning (Pitfalls)
- Firmware mismatch kills compatibility. UR CT/VT modules are not universally interchangeable across all firmware revisions. A UR8AH dropped into a relay with outdated CPU firmware may not initialize.
- Wrong CT secondary rating. Connecting a mismatched CT secondary to a configured channel will produce bad metering and potentially unsafe protection behavior. Always match CT secondary rating to relay configuration.
- Assuming it is a standalone relay. UR8AH is a module, not a complete relay. It requires a UR power supply, CPU, and chassis to function.
Installation & Configuration Guide
- Pre-Installation: ️ De-energize the UR relay chassis and disconnect CT/VT circuits per site safety rules. Photograph the existing module arrangement, CT/VT wiring, CT ratios, and VT scaling.
- Removal: Remove the UR relay from service. Release the module retention hardware carefully. Note the slot position and existing module order.
- Installation: Confirm the UR CPU firmware supports UR8AH before inserting the module. Seat the module firmly into the correct slot. Reconnect CT and VT wiring with correct polarity and secondary rating.
- Power-On & Testing: Energize the UR chassis. Open EnerVista and verify that UR8AH is recognized. Confirm CT ratio, VT ratio, phase rotation, and metering values. Perform secondary injection testing before returning the relay to protection service.
Compatible Replacement Models
- Drop-in Replacement: GE UR8AH with identical revision installed in a compatible UR relay chassis and supported CPU firmware.
- ️ Software/Firmware Compatible: Other GE UR CT/VT modules. These may provide similar CT/VT functionality but require verification of VT channel count, firmware support, and relay configuration.
- Hardware Mod Required: Non-UR CT/VT modules or third-party analog input cards. These do not fit the UR modular backplane and should not be used unless migrating to a completely new protection platform.
Frequently Asked Questions (FAQ)
Q: Is UR8AH a complete protection relay?
No. It is a CT/VT analog input module for the GE Multilin UR platform. It needs a UR CPU, power supply, and chassis to operate.Q: Will UR8AH work in any UR relay?
Not automatically. Compatibility depends on the UR relay model, CPU module, and firmware revision. Check the installed CPU and firmware before ordering.Q: Can I replace other UR CT/VT modules with UR8AH?
Possibly, but only after confirming CT/VT channel counts, firmware support, and relay configuration. Different UR CT/VT modules are not always one-to-one substitutes.Q: What CT ratings does it support?
It supports common CT secondaries for phase and ground channels. The relay configuration must match the actual CT secondary rating.Q: Does it include VT inputs?
Yes. UR8AH provides multiple VT channels in addition to the phase and ground CT inputs.Q: Is this module still in production?
Availability varies by market. Most units encountered today are surplus or inventory stock. Confirm condition, revision, and firmware compatibility before purchase.Q: Can I configure it without EnerVista?
Practically, no. EnerVista UR software is the standard tool for configuring UR relay modules, including CT/VT scaling, protection settings, and diagnostics.
