GE UR81H Multilin UR Series CT/VT Process Bus Module

GE UR81H Multilin UR Series Process Bus Module

The GE UR81H, also cataloged as the UR81H CT/VT Process Bus Module, operates as a dedicated hardware component for the digitization of instrument transformer signals and their subsequent transmission via IEC 61850 process bus communication within Multilin UR Series universal relay platforms.

Hardware Specifications

Backplane Bus Communication and Firmware Architecture

The UR81H module facilitates the transition from conventional point-to-point wiring to digital substation architectures by providing high-speed digitization of up to 24 analog CT/VT channels. It interfaces directly with the host UR chassis backplane, allowing for synchronized data transfer that satisfies the strict timing requirements of IEC 61850 sample values (SV). The module firmware manages the filtering and scaling of raw analog inputs, ensuring that digitized output streams maintain the amplitude and phase accuracy required for complex protection logic execution. Its internal architecture supports seamless integration into redundant communication networks, facilitating high availability in utility applications where fault-tolerant data paths are mandatory.

Frequently Asked Questions

Q: Is the UR81H compatible with standard copper-wired instrument transformers?

A: Yes, the module accepts analog inputs from conventional CTs and VTs, which it then conditions and converts into digital packets for process bus communication, effectively acting as an interface between legacy sensors and modern digital relays.

Q: Can the UR81H be inserted into an energized UR chassis?

A: No, strict field installation guidelines mandate that chassis auxiliary power must be isolated prior to module installation or removal to prevent electrical disturbances on the internal backplane bus.

Field Installation Guidelines

When installing the UR81H, ensure the host relay chassis is de-energized. Slide the module into the designated slot on the UR chassis, ensuring the rear connector is aligned correctly with the backplane bus. Secure the module using the provided faceplate captive screws to ensure a proper ground connection for EMI shielding. Terminate all analog CT/VT wiring at the terminal board as specified in the project wiring diagrams, and ensure that all shields are grounded to the designated cabinet common to mitigate noise pickup. Once installed, verify the module status LEDs and configure the relay software to recognize the UR81H input mapping before applying primary current to the CT circuits.