ABB RER 111C-AA Star Coupler RER 111

The ABB RER 111C-AA star coupler, also referenced as RER 111, is a passive optical device designed to create redundant fiber optic communication networks in high-voltage substations and industrial power systems. It is an integral component of ABB's solution for reliable and deterministic data exchange between protection and control IEDs, especially in applications requiring high availability such as process bus according to IEC 61850.

Function and Principle

The star coupler operates as an optical signal distribution point. It receives optical signals from one port and broadcasts them to all other ports without active regeneration. This passive operation ensures extremely high reliability and low latency, which is critical for protection signaling. The RER 111C-AA typically features multiple optical ports (e.g., 8 or 12) with ST or FC connectors, allowing the formation of self-healing ring topologies. In a ring configuration, if a fiber break occurs, the communication path is automatically reversed, ensuring uninterrupted data flow.

Application in Substation Automation

Modern digital substations rely on fiber optic networks to connect merging units, protection relays, and bay controllers. The RER 111 star coupler is used to implement redundant ring architectures that meet the stringent availability requirements of protection applications. It is particularly suited for use with ABB's IEC 61850 process bus, where sampled values and GOOSE messages must be delivered with minimal delay and zero loss. The coupler supports both multimode and single-mode fiber types, enabling distances up to several kilometers between devices.

Key Features

• Passive design: No power supply required, immune to electromagnetic interference, and maintenance-free.

• High port count: Available in versions with 8, 12, or 16 ports to accommodate various network sizes.

• Low insertion loss: Typically < 3.5 dB per path, ensuring sufficient optical budget for long links.

• Wavelength independent: Works with 850 nm, 1300 nm, or 1550 nm multimode/single-mode transceivers.

• Compact housing: DIN rail or 19" rack mountable, suitable for installation in switchgear or control cabinets.

Technical Specifications

• Optical connectors: ST, FC, or SC (specified by ordering code).

• Operating temperature: -40°C to +85°C, suitable for outdoor substation environments.

• Fiber type: 50/125 µm or 62.5/125 µm multimode, 9/125 µm single-mode.

• Dimensions (HxWxD): 110 x 220 x 40 mm (typical for 8-port version).

• Compliance: IEC 60870, IEEE C37.94, and substation EMC standards.

Reliability and Redundancy

The RER 111 star coupler is designed to meet the high reliability demands of power system protection. Its passive nature eliminates single points of failure associated with active electronics. When used in a dual-ring or self-healing ring topology, the coupler ensures that communication is maintained even after a fiber break or device failure. This makes it an essential building block for protection schemes requiring communication-based intertripping, permissive overreach transfer trip (POTT), or directional comparison blocking.

The ABB RER 111C-AA star coupler is a proven solution for utility and industrial customers seeking to build robust, future-proof fiber optic networks for substation automation and protection.