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Motor controller `bridges the gap between VSDs and soft-starts`

16 November, 2012

The British soft-start specialist, Fairford Electronics, has developed a motor controller which, it says, offers similar functions to variable speed drives, but is the size and price of a soft-starter. The energy-saving controller, called Synergy, is claimed to be 54% smaller than rival products and easy to commission, with just three items of information needed to set it up.

According to Stephen Royle, Fairford’s sales and marketing director, many customers want “the functionality of a drive, but at the footprint and cost of a soft-starter. Fairford has bridged the gap between these two differing technologies and, with enhanced energy saving, can now offer the market a unique product to suit a greater range of applications.”

The Devon-based company has invested more than £500,000 to develop the controller since it embarked on the project in 2010. The first model, with a frame size of 95 x 270 x 176mm (shown on the right in the photo above), will be able to control motors up to 100A, and is due to go on sale in December. Two more frame sizes, for motors up to 500A will be released by March 2013. (The one on left in the photo is rated at up to 200A.)

A fourth size, for motors larger than 2kA, is due by the end of 2013. Initial versions will be for 208–460V supply voltages, with a 690V model planned for 2013. A single-phase energy-optimising version is also in the pipeline.

Fairford says that it has achieved the compact size through a combination of thermal modelling and innovative cooling. There are two patents protecting the design.

According to Royle, the controller will achieve energy savings of 18–36% in fixed-speed applications. When the controlled motor is lightly loaded, Synergy will reduce the voltage and current that it supplies, thus cutting energy consumption without affecting the motor’s performance. When the motor is fully loaded, the control elements will be bypassed automatically, avoiding their losses.

To commission the controller, users will simply enter the application, motor size and the starting type. By comparison, says Royle, it can take an hour to set up a conventional soft-start.

There are several automated functions built in, including:
•  automatic pedestal, which sets the start voltage at a motor’s breakaway torque;
•  automatic end start, which determines when the motor is at full speed, to minimise the start time;
•  automatic stop, which brings the stop voltage to the motor’s stall point when soft-stop is selected; and
•  automatic end stop, which optimises the soft-stop time to give a smooth stop.

The controller, which can perform up to five starts per hour, has a colour touchscreen display and supports Modbus communications as standard, with CAN, Profibus, Ethernet, DeviceNet and AnyBus Gateway as options. Power parameters (including voltage and current) are logged and time-stamped and can be stored on a USB drive. The controller has four programmable digital inputs, four programmable relay outputs (3 NO and 1 NC), an analogue input and output, and a thermistor input.

Planned enhancements to Synergy include embedding a Web server as an aid to maintenance and servicing, and for monitoring energy savings.

Fairford employs about 40 people, 40% of them working in r&d. In the past five years, its revenues have risen from around around £500,000 to £5m. Almost half of its products are sold under other companies’ names, and 85% of sales are outside the UK.

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