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Carlo Gavazzi is offering a complete package for residential or commercial wind power generation to meet demand for small-scale renewable-energy sources.

The Mistral solution comprises a 3kW micro wind turbine, a braking control unit and an inverter.

The solution enables users to generate electricity for the home or office and feed surplus energy into the public grid.

Power is generated by a horizontal-axis wind turbine (HAWT), which offers high efficiency with a low level of audible noise, according to the company.

The 2.6m-diameter propeller provides a sweep area of 5.31m and is integrated with a generator and tail on top of a zinc-coated pole that is typically 6m in height.

This 48.5kg unit makes use of lightweight, weather-resistant materials.

Together with a specially designed blade profile, it provides high performance during dominant wind turbulence.

In harsh conditions, even when installed close to high buildings, the turbine provides up to 39 per cent of total efficiency.

When the wind speed is more than 12.5m/s, the safety ‘furling protection’ tilts the mill tail, orientating the propeller diagonally to the wind direction and forcing the propeller to slow down.

In such conditions, the maximum power is self limited to 3.3kW.

The generator is a three-phase permanent magnet unit with 18 electrical poles, designed to produce power even at low rotating speeds and providing a maximum output of 3.3kW.

It is housed in a central body assembly, which also incorporates yaw bearings, enabling the turbine to rotate and maintain the optimum heading.

Electrical connections to the inverter and control system are via a slip ring located in the tower mount.

Three-phase power at variable voltage is converted to a single-phase 230VAC output at 50Hz using the WTI3 inverter unit.

Carlo Gavazzi claims that a safety and monitoring system maintains efficiency to about 95 per cent and guarantees immunity from electromagnetic influence within international EMC standards.

Full digital control ensures low current distortion of better than three per cent, along with output frequency detection and synchronisation.

Also integrated is the company’s maximum peak power tracking technology to maintain optimum wind power output.

Active anti-islanding protection is provided for grid monitoring to ensure high levels of installer and user protection.

The WTB3 braking box sits between the generator and inverter, providing automated or manual control of the turbine.

In its basic form, this unit ensures safe operation, acting as the main breaker from the generator to the grid.

The inverter drives two different electromagnetic brakes: a resistor brake, which operates when the wind speed reaches more than 13.5m/s; and a short-circuit brake that takes over if the resistor brake is activated repeatedly in a short time or if the wind turbine speed increases despite the action of the resistor brake.

Manual brakes are provided via a mushroom switch and a maintained-action pushbutton.

A braking unit and an inverter are available separately or within a complete packaged WTC3 wind turbine cabinet that also integrates surge protection, along with the facility to monitor power output using a MID-compliant energy meter connected via an RS-485 interface, grid interface and breaker.

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