Gearbox Failure of a Wind Turbine – just how very fatal is it?

A wind turbine displays the most intricate and marvelous use of gears and bearings at present. Ever noticed how slow the blades rotate? Yet, one single turbine is capable of producing almost 1.65 MW of power. Such a high value requires huge rotational speed for the generator inside, and this is achieved through the use of gears. But, what if this system malfunctions? Is gearbox failure fatal to the turbine or the grid? Find out here.

Gearbox malfunctioning of a wind turbine

Gears are placed in a particular order to maintain every variable within their rated values. For instance, the blades are designed to rotate at a specific speed and any increase here will cause the whole rotating equipment to collapse. Similarly, the prime mover speed of the generator inside must not fall below/rise above a particular limit to maintain a particular output voltage.

Now consider that the gearbox of a just one particular turbine in the whole unit starts malfunctioning. This, in turn, will cause prime mover speeds to equal the value of the turbine itself. At such low speeds, the following scenarios are likely to occur in sequence:

• Low speeds will cause output voltage to fall.
• If the generator is connected to a grid, falling voltage will cause power to flow into the generator in the reverse direction. Current may increase above the rated value.
• This in turn will decrease bus voltage at a particular point and circuit breakers will cut off the whole connection.

The whole grid system will be affected which will result in a mass power cut. Falling voltage is a menace to an electrical power system and has an impact on a lot of systems simultaneously. For instance, if a power plant shuts down due to this, it will take a whole 24 hours just to fire it back up.

Hence, gearbox and rotating equipment analysis is such an important step for all power industries. The reason is quite simple. The whole power generation process with wind turbines is a continuous, 24 hours’ process. Gears are bound to suffer from wear and tear and any change in teeth dimensions will have a direct effect on generator output.

Quality Assurance Audits – a necessity

As under no possible condition should the grid voltage fluctuate beyond a certain tolerance limit. Only authentic firms with personnel who have undergone a detailed gear and bearing training must be employed. Proper analysis includes:

• Inspection of every gear for damage.
• Teeth ratio of every gear must be maintained.
• Decision on replacement of any gear.
• Necessity of lubricant, if required.

Every single part and component have a purpose to serve in such a complex rotating equipment design. Take the simple ball bearing for instance. Any damage here will cause the internal components to shift and speed will reduce due to alarming levels, even when gears are intact and in a perfectly working condition.

So, do not wait around for a gearbox failure to occur. Things will fall out of hand in a matter of minutes and damage caused will be irreparable. Plus, ultimately all wind turbines are connected to the national grid. As stated, one unchecked damage will cause a whole region to shut down. Employ trained professionals regularly for audit and make a purchase only from the reputed ones.