Yokogawa ANB11D-225 ESB Bus Node Unit: 220 V AC Redundant Power for CENTUM VP

Description

The Yokogawa ANB11D-225​ is an Optical ESB Bus Node Unit manufactured by Yokogawa Electric Corporation. It serves as a remote field-input/output (I/O) aggregation hub within Yokogawa CENTUM VP distributed control architectures, collecting analog and contact signals from field devices and relaying them to a Field Control Unit (FCU) over a redundant fiber-optic ESB bus.

Physically, the ANB11D-225​ is a 19-inch rack-mount chassis that houses dual-redundant power supplies, ESB interface modules, optical repeater modules, and up to eight FIO modules. Its suffix configuration denotes a dual 220–240 V AC power supply arrangement, basic (non-explosion-proof) protection, and the BU2A connector unit.

Application Scenarios

At a Middle Eastern refinery, the central control building and several remote instrument enclosures were separated by more than two kilometers of cable trays crowded with high-voltage feeders and variable-frequency drives. Running copper I/O links was out of the question—ground loops and electromagnetic noise would have made 4–20 mA readings unreliable. Instead, the engineering team deployed the Yokogawa ANB11D-225​ in each remote cabinet, connecting them to the AFV40 FCU over dual redundant single-mode optical fibers.

Commissioning told the story. Even with a nearby 6.6 kV motor starter kicking on, the ANB11D-225​ maintained clean communication diagnostics and millisecond-level update rates. More importantly, when a contractor accidentally severed one of the fiber pairs during civil works, the node unit’s second optical path carried the traffic without the operators noticing—no process interruption, no alarm flood, just a diagnostic note in the event log. For the plant, that resilience justified the optical architecture.

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