The First Commercially Viable Vertical Axis Wind Turbine

Vertical Axis Wind Turbines offer a very reliable, efficient and cost-effective alternative to conventional Horizontal Axis Wind Turbines. Vertical Axis Wind Turbines are less intrusive visually, even in areas such as National Parks and Areas of Outstanding Natural Beauty. These turbines are quieter, more bird and bat-friendly and are less expensive to maintain compared to horizontal turbines.

The 4N-55 is a 55 kW rated vertical axis wind turbine. Three years in development, the radical new design is manufactured in the UK and incorporates a wealth of patented design features, which greatly enhance power generating output at low wind speeds and significantly reduce the total costs of ownership. The design team includes world leading aerodynamic, mechanical and electrical engineers.

Key
Features
The 4N-55 is designed & manufactured in the UK.
The 4N-55 does not require sensors or motors to position itself into the wind, thus negating the need for complex control gear, eliminating a major cause of both horizontal and vertical axis wind turbine failure.
The 4N-55 is self-starting.
The 4N-55 has regen speed control in high winds and does not require a blade pitch control system eliminating a cause of failure and additional maintenance cost in other wind turbines.
The 4N-55 boasts superior performance in turbulent air flow and gusty conditions.
The 4N-55 has a low rotor RPM (34 RPM max) which reduces wear and in turn maintenance costs.
The 4N-55’s power electronics, motor and gearbox are all at ground level. Allowing for easy, low cost maintenance.
Environmentally friendly concrete free screw pile foundation solution.
Quick installation with minimal plant.

Technical Data & Specifications

Electrical Data
generator type	90 kW Induction Motor
voltage	400 Volts
poles	Multiple
converter	Active front end regenerative full scale converter
feedback	Closed Loop
design / safety	G59, EMC Directive BS EN 61800-3, Machinery Directive EN 60204-1

Operating Data
rated power @ 11 m/s	55 kW
maximum power	65 kW
cut in wind speed	3.5 m/s (7 mph)
cut out wind speed	25 m/s (55 mph)
survival wind speed	59.5 m/s (133 mph)

Physical Data
mill diameter	14 m
blade length	14 m
number of blades	5 (3 for higher wind speed sites)
nominal rpm	34 RPM
braking system	Regenerative braking with dual fail-safe mechanical braking and hurricane load stationary parking brakes.
tower type	Tubular mast
height	Hub Height: 23 or 30 m / Tip Height: 30 or 37 m
design specification	IEC 61400 – 2 wind turbine standard
power up sequence	Self Starting
electrical housing	External IP54 enclosure with internal IP2X protection

Reliability, Maintenance & Warranty

One of the key design briefs of the 4N-55 was to develop a low maintenance system. This has given 4Navitas the confidence to offer a 5 year conditional warranty as standard and a 20 year warranty as an option.

Due to the design characteristics of the 4N-55 and the fact that majority of the serviceable components are at ground level, repairs and servicing can be carried out expeditiously without the requirement for expensive craneage and cherry-pickers. Unlike other wind turbines the 4N-55 has very few serviceable components at height.

Our state of the art 24 hour remote performance monitoring system means that in the unlikely event of a fault we will be notified by email and SMS. We will probably contact you for access to the turbine before you are even aware that the fault exists.