Fibre optics link pumps

The Downlands Scheme is an irrigation project designed to take water from the Waitaki River and irrigate up to 10,000 ha of dry farmland in the Black Point, Enfield and Napara areas near Oamaru in New Zealand.

During the planning stages, the senior electrical and control systems engineer from Beca Infrastructure contacted Lloyd Bennett, the data and communications specialist from the Corys Electrical and MasterTrade group of companies, to discuss the best fibre-optic backbone options required to link the seven pump stations together.

With this in mind, a singlemode fibre-optic backbone was recommended due to the distance between pump stations. This also provides for the additional bandwidth in the network if the scheme is expanded in the future.

MasterTrade Oamaru looked after the main requirements of this project. Andrew Hobson, the branch manager, and his team coordinated the logistical requirements of getting 10,200 m of fibre-optic cable to the site, as well the large quantities of duct pipe and associated product. They also supplied the fusion-splicing equipment and accessories to the project engineers, Delta Utility Services from Dunedin.

Industrial Controls South Canterbury carried out the secondary works of commissioning the network, which included the OTDR testing of the fibre-optic backbone.

The EOTec 2000 range of Weed Instruments fibre-optic modems was the preferred choice for the project's fibre-optic backbone structure.

Two fibre backbones have been configured for this project. One backbone provides a Modbus fibre network and the second backbone facilitates ethernet fibre network between the various pump stations. The backbone is configured in a self-healing ring mode, which gives fibre media redundancy in case 'the loop' is broken.

Data will always be routed on the shortest possible path to reduce propagation delay through the system. Most process plants and factories have unique requirements for communication networks that differ from those of a commercial network. Industrial network components must withstand harsher environmental conditions such as extreme temperature ranges, lightning strikes, electromagnetic interference and hazardous locations.

Mounting and spacing requirements are also an issue since industrial networking components must be mounted in the same control panel with other control equipment. The modular EOTec brand of industrially hardened fibre-optic communication products from Weed addresses these issues and provides optimal solutions for factory automation and process control.