Electricity and Control March 2024

DRIVES, MOTORS + SWITCHGEAR : PRODUCTS + SERVICES

Scaling up drive production with incremental improvements

Variable frequency drive (VFD) manufacturer Invertek Drives is a leader in the innovation and development of electric motor control technology. Over the past ten plus years, a series of incremental improvements have enabled the company’s growth and helped it improve its energy efficiency. It first approached power quality specialist CP Automation in 2012 and, over the years, CP Automation has supported Invertek Drives by supplying innovative regenerative braking and harmonic mitigation technology. Based in Wales, Invertek Drives specialises in the design and manufacture of electronic variable frequen cy drives (also referred to as variable speed drives, or VSDs), which it supplies to customers around the world. Using VFDs to adjust the speed of an electric motor to match the actual load requirements provides several benefits, such as energy savings, improved process control and reduced maintenance costs. The company assembles, customises and tests the VFDs on a bespoke process line, or global assembly cells (GACs). A GAC is a chain of connected worksta tions, each performing a step in the production and test ing process. GACs are modular, enabling Invertek Drives to scale up production by adding more workstations when it needs to meet increased demand. Originally, Invertek Drives used third-party dc drives and motors and braking resistors on its GACs to test the VFDs it manufactured. However, dc motors require more maintenance than ac drives, particularly with regard to replacing the brushes. The dc motors were also creating noise and heat, re quiring a blower motor to keep them cool when running. As Invertek Drives expanded and added more GACs to its facility, the team found that power consumption was a growing challenge and contacted CP Automation for assistance. CP Automation initially recommended switching to ac motors and fitting a REVCON regenerative braking unit to each GAC, to capture and recycle energy otherwise lost to the braking resistors. The move to ac motors also allowed Invertek Drives to use its own VFDs to test its products, reducing reliance on third-party suppliers. “As our production process evolved, energy saving became a key priority for us,” said Peter Evans, Manufacturing Engineering Manager at Invertek Drives. “Initially, we were pulling 30 amps of current from the

In the production facility at Invertek Drives.

Scaling up As Invertek Drives’ products grew larger, the company needed to scale up its GACs while maintaining high en ergy efficiency. At that point, CP Automation worked with Invertek Drives to create a second, much larger system with a capacity of 200 A and recommended installing REVCON harmonic filters on the GACs used for the test ing of the drives. “After working with CP Automation to install harmonic filters on the larger system, we saw improved quality and reliability in our internal testing,” said Brian Walker, Senior GAC Engineer at Invertek Drives. “The dc bus remained stable, the control side for loading was more consistent and the input phases were more balanced, all of which helped when we tested our drive products.” John Mitchell, Global Sales and Marketing Director at CP Automation highlighted: “The design height of the GACs meant space was an issue. However, by installing two smaller harmonic filters in series we met this space constraint. “The units also provided incremental improvements – like reducing heat losses, improving phase angle and boosting the dc bus on the load drive, which all added up to improve efficiency,” Mitchell noted. “The braking units boosted efficiency and the har monic filters improved reliability,” added Evans. “The production process is more streamlined and has helped us manufacture an even more reliable product for our customers.” He said too: “The reliability of CP Automation’s sys tems has been great; one of the first units installed around ten years ago is still running now. One of the rea sons we’ve kept working with CP Automation is because the technology is so reliable. “The equipment CP Automation supplied worked re ally well on the small system, it worked well on the large, and now we’re going extra-large and working together on a third system that will go up to 450 A,” Evans said. CP Automation emphasises that by making small changes progressively, introducing regenerative brak ing systems, harmonic filters and other effective energy management equipment, industrial facilities can boost productivity and remain competitive. □

Invertek Drives uses General Assembly Cells in the production, assembly and testing of its VFDs.

supply during the load cycle, but after working with CP Automation, we were pulling only 25 per cent of that. “This saving meant we could install more GACs to match increased demand without needing to upgrade the mains power supply,” Evans continued.

12 Electricity + Control MARCH 2024