A US based maker of custom ventilation and refrigeration systems for potato and onion storage uses ABB’s advanced drive technologies are used to provide precise, on-site and remote environmental control that helps ensure vegetable quality and reduce mass loss (shrinkage), while saving energy.

Each potato and onion variety has its own temperature and humidity requirements for optimum quality and our systems need to hold very accurate settings – within a tenth of a degree – to allow food storage up to 12 months.

To achieve this, an ABB general purpose drive is used to control fan-motor speed and airflow, keeping temperature and humidity at precise settings. Incorporating drives enables the fans to run more efficiently by matching air volume precisely to demand. When air demand decreases, the variable speed AC drive slows the motor down, saving energy and helping farmers maximise their sales margins.

Six for the price of one

In a typical installation used for onion storage, six 18.5 kW drives use about 19.2 kWh at 100 percent speed. If the fans are reduced to 50 percent speed in the winter, when storage volumes are down and the outside temperatures are low, each of the fans use about 2.8 kWh. All six fans at 50 percent speed use less energy than one fan at 100 percent speed and this provides improved air handling and lower energy costs .

Remote control improves safety and efficiency. Even more important than the energy savings is the safety and efficiency the new systems provide through remote control and monitoring, because storage facilities are often located many miles from the main offices. With the old system there was no warning of high motor current and overloads would trip until the system was reset.

Remote monitoring & control

With the optional intelligent Ethernet module, the drives can be monitored remotely, either through a modem or via the Internet, allowing faults to be quickly diagnosed and solved, without the need to visit the storage site. Communications can be set up to send an alert via e-mail to the operators to warn them when a fault trip occurs. Other system components such as such refrigeration units, fans, drives and doors are also integrated within the network for remote monitoring.

Products are kept fresh while being stored for extended periods by the variable speed drives that control ventilation fans to keep stored produce at correct conditions of temperature and humidity.  Vegetables can be stored for up to 12 months without a reduction in quality and power can quicky be adjusted when the storage environment changes.

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