Drives: Maintaining performance and reducing failures

Environmental factors such as heat, dust, moisture and high peak loading can take their toll on inverter and servo drives. The sales of drives rocketed during the '90s and many are now reaching an age where they will need attention to prevent performance degradation and possible failure.

The cost of a full health check, repair and recondition service for both inverter drives and servo equipment is minute compared with the costs of production downtime on any size of drive. The cost of maintenance and repairs on medium and large-sized drives will also be far less than a replacement, should problems arise.

Mark Jackson of the Deritend Group comments, "Medium and larger drives, over about 30kW, will invariably cost significantly less to repair than new replacement units. In contrast, we tend to replace any item up to around 7.5kW automatically because the piece cost has reduced significantly in recent years."

Jackson noted that larger drives can cost tens of thousands of pounds new and are usually crucial to production or the operation of an installation. These, he noted, are the drives that need most care and attention, and should be checked regularly, particularly if they are approaching 10 years old.

Inspection and cleaning is recommended for electrical components such as fans, IGBT (insulated gate bipolar transistor) packs and capacitors that naturally degrade. PCBs, meanwhile, can work loose, crack and suffer from heat damage, while components are also prone to collecting dust and particle debris that can cause damaging heat build-up.

Fans are another vulnerable area, as effective ventilation is vital and fans tend to wear out before other components, the Deritend expert continued. "Problems with cooling inside the cabinet can easily reduce the life of a drive by 50% and are more common than component failures, often being the root cause of a failure that is attributed to overheating."

Jackson recommends regular visual checking of drives, as well as thermographic surveying to identify hot-spots inside and outside drive cabinets. His other useful tips include making a copy of any drive parameters and bespoke programmed software, just in case a failure occurs and it affects the drive software.