Wind classes
Wind classes according to International classification, and wind density:
| 10 m (33 ft) | 50 m (164 ft) | 10 m (33 ft) | 50 m (164 ft) | |
| Wind Power Class | Wind Power Density, (W/m2) | Speed, m/s (mph) | Wind Power Density, (W/m2) | Speed, m/s (mph) |
| 1 | ||||
| 2 | 100 - 150 | 4.4 (9.8)/5.1 (11.5) | 200 - 300 | 5.6 (12.5) - 6.4 (14.3) |
| 3 | 150 - 200 | 5.1 (11.5) - 5.6 (12.5) | 300 - 400 | 6.4 (14.3) - 7.0 (15.7) |
| 4 | 200 - 250 | 5.6 (12.5) - 6.0 (13.4) | 400 - 500 | 7.0 (15.7) - 7.5 (16.8) |
| 5 | 250 - 300 | 6.0 (13.4) - 6.4 (14.3) | 500 - 600 | 7.5 (16.8) - 8.0 (17.9) |
| 6 | 300 - 400 | 6.4 (14.3) - 7.0 (15.7) | 600 - 800 | 8.0 (17.9) - 8.8 (19.7) |
| 7 | >400 | >7.0 (15.7) | >800 | >8.8 (19.7) |
The wind speed according to Beaufort scale and its influence on the Wind Turbine (WT) operation, is shown in the Table:
|
Beaufort scale |
Wind speed, m/sec |
General description |
Detailed description |
Effect on WT |
Conditions for WT operation in this range of wind speed |
|
0 |
0,0-0,4 | Calm | Smoke from pipes is vertical | No | No |
|
1 |
0,4-1,8 | Light air | Smoke from pipes has some angle with vertical, weather-vane are motionless. Some ripples on water | No | No |
|
2 |
1,8-3,6 | Light breeze | Face feels the wind, leaves rustle, water is choppy | Wind rotor starts rotating | Not acceptable |
|
3 |
3,6-5,8 | Gentle breeze | Leaves are oscillating, light flags are fluttering, some white caps on water | WT starts producing power | Satisfactory for alternator |
|
4 |
5,8-8,5 | Moderate breeze | Leaves are oscillating, the dust and small papers fly, lots of white caps on water | Power of WT reaches 50% of nominal | Good for alternator |
|
5 |
8,5-11 | Fresh breeze | Broad-leaved trees start swinging, all waves are in white caps | Power of WT reaches 75% of nominal | Very good |
|
6 |
11-14 | Strong breeze | Big branches of trees are swinging, telephone wires are bussing, big white caps on waves | Power is closed to maximum | Perfect for WT. Aerodynamic brakes start operating |
|
7 |
14-17 | Moderate gale | All trees are swinging, foam is flying from waves | Maximum power |
Perfect for WT. Aerodynamic brakes operate |
|
8 |
17-21 | Fresh gale | Branches of trees are breaking, it's hard to go against the wind, foam flocks are flying on the water | Maximum power |
Perfect for WT. Aerodynamic brakes operate |
|
9 |
21-25 | Strong gale | Small destructions, smoke pipes fall down | All Horizontal Axis Wind Turbines (HAWT) stop operating | Acceptable. WT of SRC-Vertical continue operating |
|
10 |
25-29 | Whole gale | Serious destructions, trees pull out together with roots | Limit loading for HAWT | Acceptable. WT of SRC-Vertical continue operating |
|
11 |
29-34 | Storm | Great destructions | Damage of some Wind Turbines | Acceptable. WT of SRC-Vertical continue operating |
|
12 |
More than 34 | Hurricane | Devastating destructions | Serious dmamge of Wind Turbines, some fall down | Acceptable. WT of SRC-Vertical continue operating |
|
- |
35-60 | Hurricane | Consequences are unpredictable | HAWTs fall down | Quite acceptable. WT of SRC-Vertical can fall down on appr. 60 m/sec |