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Ready when you need it

April 6, 2017

Konecranes new VFD Capacitor Reforming service helps keep your variable frequency drives (VFD) ready when they are needed, without having to remove them from your facility.

A VFD is a type of motor controller that controls the speed and torque of an electric motor by varying the frequency and voltage supplied to it. Widely used in crane applications, a VFD offers a vast array of benefits, including reduced load swinging and more precise control of movements, among others.

Since a spare VFD is sometimes stored for extended periods of time between uses, it must be reformed to recondition the electrolytic capacitors – a primary section of a VFD's main power circuit – and restore their condition to prepare for operation.

According to Saku Aspelin, Product Manager, Consultation Services at Konecranes, VFDs can be quite expensive. “A bigger unit can cost tens of thousands of euros, so it is worthwhile to keep them in good shape. There are typically multiple VFDs on a single crane, at least as many as there are directions of movement.”

Power without the bulk

“VFDs can be bulky, especially when talking about bigger pieces of lifting equipment, such as process cranes or port cranes, meaning it does not make sense to ship the VFDs off-site. And yet, the reforming previously had to be provided by a trained specialist, since the power sources to do the job off-the-shelf are fully manual. As such, you would have to have expertise in this field.” explains Aspelin.

Now fully automated and portable, the new device has “the knowledge of the specialist” built into it.

The main challenge for Konecranes was to create a power supply that was capable of doing all this at a compact size. “We realized we could develop our own device following our specs, make it smaller and portable, and then distribute these all over the world so we did not have to send a specialist from a dedicated service location to do this job,” he continues. Now fully automated and portable, the new device has “the knowledge of the specialist” built into it.

Supporting business continuity

Using this smaller, fully-automated portable DC power source, a certified electrician reforms the capacitors in the DC-bus of a customer’s VFD. The electrician then issues a certificate of service and labels the VFD. The certificate includes the date of the next recommended reform, should the VFD remain idle for another year.

The VFD Reforming service also includes a visual inspection in an effort to identify faulty devices and to make recommendations for corrective actions. These services help customers be prepared in case of future incidents that could affect the continuity of their business, by attempting to keep those VFDs ready for service when they are required, without ever removing them from a facility.

Now we are able to provide the service cost-efficiently and conveniently on-site.It’s one thing when a crane’s VFD breaks down. It’s another when the spare device that was stored in case of emergency has not been kept in a ready-to-use condition. Placing a backup VFD that has not had its capacitors revived annually could result in a failure when put into use.  

“It’s the VFDs that are stocked as spares that potentially create some risk,” concludes Aspelin. “And when you blow a spare, you can potentially face significant downtime for the crane. Now we are able to provide the service cost-efficiently and conveniently on-site.”

Key advantages

  • No need to ship the VFDs to another location.  The benefits of this new service come from cost-efficient revitalization at customers’ respective sites.

  • Spare VFDs are in ready-to-use condition if and/or when you need them.

  • Aims to identify faulty spare VFDs before they cause prolonged downtime.


Text: Gino de la Paz
Photos: Konecranes

Expert spotlight

  • Saku Aspelin is responsible for managing the Consultation Services offering of Konecranes globally.

  • He has also held positions in R&D and Global Product Management.

  • Aspelin started his career with Konecranes as a technician in 2002.