UR-4LH | GE Multilin | Digital I/O Module

GE Multilin UR‑4LH Digital I/O Module

Configured for digital signal execution in Universal Relay (UR) frames, the GE Multilin UR‑4LH (UR‑4LH digital I/O module) provides Form‑A latchable output functionality for auxiliary control and interlocking applications within UR‑series protection systems. The module integrates 14 latchable outputs and operates as a high‑power variant of the UR I/O family.

Hardware Specifications

Backplane Bus Communication Velocity and I/O Density Scaling

UR‑series digital I/O modules rely on deterministic backplane timing to ensure predictable output activation and latch behavior. The UR‑4LH’s high‑power design maintains stable rail loading, preventing timing drift during simultaneous multi‑card operations. I/O density scaling across UR frames allows mixed Form‑A, Form‑C, fast Form‑C, latching, and SSR cards to coexist without firmware flash incompatibility, provided modules remain in their original slot positions.

Frequently Asked Questions

Q: Can the UR‑4LH be hot‑swapped while the relay remains energized? A: No. Control power must be removed before insertion or extraction to avoid unintended output transitions and backplane state faults.

Q: Does the UR‑4LH impose any special backplane current requirements? A: As a high‑power digital I/O module, it draws more rail current than low‑power variants, but remains within UR‑series backplane limits.

Q: Are firmware updates required when replacing a UR‑4LH with another Form‑A module? A: No firmware resides in the module. Slot position must be preserved, but configuration remains at the relay CPU.

Field Installation Guidelines

• Remove control power before handling the module.
• Open the hinged front panel fully to access module bays.
• Record the original slot position; UR modules must be replaced in the same location.
• Use inserter clips to slide the module smoothly into the bay and ensure both clips lock simultaneously.
• Maintain clean connector surfaces to ensure stable backplane seating.
• Follow ESD precautions when accessing relay internals.