Improving Gearbox Reliability in Wind Turbines - MetalSCAN by Gastops

Gearbox reliability has always been a problem in the wind turbine industry, and continuing design modifications have not been able to fix all the issues with gear damage and turbine bearing. Therefore, owners and operators of wind turbines not only have to manage these reliability problems, but they also must minimize the impact they have financially.

Gastops has developed a solution to this that reduces the cost of gearbox repair and removal, as well as causing a reduction in down time and in turn, lost revenue.

With 20 years of experience in monitoring bearings and gearboxes and 24/7 support for customer service and monitoring for all installations, Gastops developed the MetalSCAN.

MetalSCAN allows online debris monitoring, detecting and supervising gear damage and turbine bearing. The MetalSCAN is fitted to the oil circulation system and from here, picks up non-ferrous and ferrous metallic particles, which appear when the components are damaged.

Above the size threshold, the product has 100% detection rate of metallic particles, allowing the ‘earliest possible detection’ of damage. The quantification of the metallic particles indicates how much damage there is to the components.

The MetalSCAN can also discriminate between ‘build’ and ‘surface fatigue’ types of damage debris and differentiates between ‘auxiliary components’ and ‘bearing’ damage.

It also enables owners and operators to have reliable condition indication, reporting on the life stage of the bearing or gearbox and indicating how much longer it will remain operational.

One of the many benefits of the MetalSCAN is that the data it provides will avoid more ‘failure’ events by containing the component’s damage and reducing the time it takes for them to be repaired.

Due to the damage containment, it also dramatically reduces the overall cost of repair and minimizes penalties. Not only do these benefits reduce business interruptions, but it also allows repairs to be scheduled on-site before full shutdown and maintenance to be carried out regularly based on the condition indication.

There are two options to use for the MetalSCAN Communications Interface. Option 1 consists of a Turbine Controller or a Monitoring System. Alternatively, option 2 uses an Ethernet network interface or a GPRS/GSM Network Interface.

The product line consists of different models to suit the needs of each owner or operator and interpretation of MetalSCAN’s results don’t require an expert. Custom or standard solutions are available for all gearboxes, and the condition indicators are developed based on the specifics of the application.

How the MetalSCAN sensor works:

The MetalSCAN Sensor: a three-coil assembly, wrapped around the tube carrying the oil. The inner coil (yellow) measures disturbances and the outer coils create alternating magnetic fields.

The System Processor Output: a magnetic metallic particle disturbs the magnetic field, whereas a non-magnetic metallic particle produces the opposite signal. The frequency is proportional to velocity and the amplitude is proportional to size.

Condition Indication:

The debris size profile determines the damage mode. The graphs demonstrate the alarm limit and debris generation trend.

The alarm limit and debris generation trend determines the remaining life of the component and the estimation can be repeated as necessary.

MetalSCAN Limits:

Definition: C = Cumulative particle counts detected by MetalSCAN sensor, K = Constant (counts/mm2), A = Angle of spall damage (degrees), D = Planet bearing pitch diameter (mm), w = Planet bearing rolling element width (mm)

The alarm is the recommended maximum amount of damage and the component should be removed from operation.

The warning is an early indication that damage has begun to progress and the components should be checked to confirm the extent of the damage.

MetalSCAN vs Other Methods

Optical Based Particle Counters

  • An effective way to measure the cleanliness of oil
  • Not as sensitive to early damage of bearings or gears
  • Air bubbles cause false readings

Oil Analysis

  • Uses an off-line sampling process that requires a 6-month sampling period at the minimum - this makes it labor intensive and leaves it open to human error
  • Needs an expert for results interpretation

Vibration Monitoring

  • Less senstitive to early damage (particularly in planetary stage)
  • Does not clearly indicate the degree of damage
  • Needs expert interpretation

MetalSCAN Installation

Thumbnail Image Credit:Paragorn Dangsombroon/shuutterstock


  1. Martin Mizera Martin Mizera United Kingdom says:

    The best way to prevent turbine gearbox failures is to use direct drive turbines and eliminate the gaerbox.

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of

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