A Variable Speed Drive is used in a variety of industries to control the speed and torque of an electric motor. This is achieved by the drive varying the motor input frequency and voltage.  

The variable speed drive (VSD) operates alongside the electric power supply. Power is supplied as a fix speed, however if the motor requires to operate at different speed, this is where a variable speed drive is used. As a result of high volumes of current passing through the variable speed drive, there are various faults which can impact the performance. 

Faults within a Variable Speed Drive  


Ventilation within the VSD is crucial, if not this can lead to overheating. Heat is generated during operation, therefore cooling through ventilation is required. Overheating can lead to increased wear and tear, reduced efficiency and can result in a complete failure of the drive.  

To prevent your VSD from overheating, ventilation is key to reduce heat build up. When installing your VSD, take into consideration the environment and location which it is situated to minimise the risk of overheating.


It is important for the VSD to be configured with the load which it is operating to minimise the drive becoming overloaded. If the load is changed, the configuration must be re-assed to be correct. If not, this can lead to overheating, reduced machinery lifespan or even failure.  

Engineer holding a circuit board

To prevent the VSD from overloading, follow the manufacturers guidelines and specifications to make sure you have the correct VSD, for the motor size which it is controlling.

Electrical Faults: 

Electrical faults can have an impact on the components within the variable speed drive, or interfere with the operation. Issues which can occur are voltage spikes, power surges or electrical noises. It is important to prevent these faults by electrical protection measures. Regular maintenance checks will minimise unexpected breakdowns from happening.

Software Errors:  

Drives use complex software to operate efficiently. Incorrect parameters and programming errors can lead to operation faults, resulting in the drive operating inefficiently. To prevent software errors, make sure you are following the manufacturing guidelines for your VSD, this will help reduce errors during the operation of the VSD during installation.

Voltage Fluctuations: 

Voltage fluctuations impact the stability and performance of a Variable Speed Drive. If the fluctuations happen regularly, this can cause erratic behaviour or damage to the drives components. To prevent voltage fluctuations, use a voltage regulation device, this will stabilize the incoming power supply.

Input/Output problems:  

During the operation of a variable speed drive, if there are issues with the power input this can have an impact on the variable speed drive operation. Issues such as loose connections or sensor problems, are examples of problems within the variable speed drive. 

Wiring Issues: 

Malfunctions may occur if there is poor grounding or incorrect wiring connections within the Variable Speed Drive. This can lead to electrical hazards and can create a safety hazard within the workplace. 

Component Aging: 

Overtime, components will degrade and need either repairing or replacing. As a result of wear and tear, efficiency will reduce and eventually a failure will occur. To reduce this from happening, regular maintenance of your VSD will allow these faults to be identified early.  

Preventative Maintenance: 

Similar to most machinery assets, regular inspections is key to identifying faults early. It is important to look out for worn components, loose connections and any visible damage. If there is a build-up of dust or dirt, this should be cleaned regularly to reduce the risk of overheating. Following the recommended maintenance schedule from the manufacturer is important, this will provide you with a suggested maintenance plan for the machinery asset, maximising machinery efficiency and life span.  

Regular maintenance is important to reduce these faults occurring. Neutronic have highly experienced Electronic Engineers, who regularly complete repairs on Variable Speed Drives. Contact us today to book in your repair, enquiries@neutronictechnoloiges.com