Plane sailing for frequency converter

2012-12-03 - The Lopen Liito-Veto cooperative pioneers the use of a frequency converter for electric-powered glider winches in Finland. The electrically operated winch reduces costs, is quiet, and ensures a smooth takeoff.
An electric winch takes the glider to the release altitude in less than a minute. From there on, the journey continues with the help of columns of rising air, or thermals. There are approximately 1,600 glider pilots in Finland.

Globally speaking, an electrically operated glider winch is not unique, but in Finland there are only ten winches in active use, all of which are powered by combustion engines. Now, thanks to Lauri Mattila, the leader of Lopen Liito-Veto cooperative, there is at least one electric winch in Finland making use of a frequency converter.

The data gathered during the summer at the Räyskälä and Kiikala airports reveals that the electric winch saves money, time, reduces noise levels and reduces emissions.

The primary aim for the development of the device was cost savings: the average cost of a single aerotow launch is EUR 25–30, while the corresponding figure for a single electric winch launch is approximately EUR 5 .

In winching applications, the frequency converter feeds electricity stored in batteries to a motor, which rotates a reel equipped with a 1.5-kilometer-long launching line. The frequency converter is used to control the reel's rotation speed and torque, which is dependent on the size of the glider.

Unknown potential

The operation data is automatically collected during each launch and analyzed to help develop the optimum winch launch.

What makes the Lopen Liito-Veto winch so special is that the motor shaft is attached directly to the reel without a gearbox. “The winch is a good application for a frequency converter. We do not even know all future possibilities for the device with regard to automated winch launches,” says Jari Kilpeläinen, ABB's Motors and Generators unit sales manager and glider pilot.

What is also unique in the equipment package is the return winch also features a frequency converter. After the launch, once the glider drops its launch line, the winch pulls it back to the launch site with the help of an auxiliary line. The system is the first of its kind in Finland, and no electrically operated version is known to exist elsewhere in the world.

According to Jari Kilpeläinen, the glider pilot can feel the difference between an electrically operated winch launch and an aerotow or diesel operated winch launch. “The pull is more even,” said Jari Kilpeläinen, a well practiced glider of more than 30 years having given instruction in gliding and launched gliders with both aeroplanes and winches.

The price of a frequency converter-powered electric winch package including the required development work is approximately EUR 50,000.

A frequency converter-powered winch
  • Built on the platform of a truck housing dozens of batteries, a motor with a rating of 132 kilowatts and 750 rpm, and an electrical cabinet containing the frequency converter. The cabin of the truck is equipped with rear windows. The winch launch is controlled with the help of terminal devices located in the cabin.
  • The truck is registered for road use and can be used at any airport.
  • It has taken several years to develop the package, and it took two years to build it. With the exception of the frequency converters, all equipment has been recycled.
The consumption caused by the launching of a glider to an altitude of 500 meters
  • An aerotow launch: 6 liters of aircraft fuel, approximately EUR 18
  • A combustion engine winch launch: 1 liter of diesel fuel, approximately EUR 1.5
  • An electric winch launch: 2 kWh of electricity, approximately EUR 0.2

Frequency converters
The frequency converter powering the actual extracting winch is ABB's inverter module ACS800-104-0320-3 (320 kVa).
The frequency converter powering the return winch used to withdraw the line is ABB's ACS800-01-0020-3 (20 kVa).

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