New drives boost reliability

The roller table has 80 rollers to transport finished steel billets at Celsa Manufacturing’s plant in Cardiff. Each drive controls four banks of 20 roller motors.

Celsa’s electrical engineer, Nicholas Drane, explains: "The existing drives could not be interrogated to discover what they are doing or what condition they are in. It was also getting difficult to source spares for them.

"We had tried using another manufacturer’s drives to replace them but these needed extra components such as RC filters and braking resistors and we never managed to make them work in the way we wanted. This lead to a lot of lost production which, as a 24/7 operation, we cannot afford.”

Celsa had previously worked with ABB authorised value provider, APDS, and already uses ABB’s DC drives on site.

As a trial, APDS installed an ABB general purpose drive, ACS550. "We were keen to know that the solution worked before we made major changes to the cabling,” says Drane. "APDS installed a drive as a temporary measure. Once we were satisfied, APDS installed the permanent drive over the shutdown period so there was no disruption.”

"Although the main objective of the project was not energy saving, we estimate that Celsa will be saving in the region of 30% on its energy costs for this drive,” says Doug Pitt of APDS.

"All the motors are connected to the drive using scalar control,” says Pitt. "Some drives do not like the inductance imbalance that goes with trying to control so many motors, but with the ABB drive, we simply size it for 20 motors and there is no need for a filter.”

The 125A ABB drive used on the application incorporates a swinging choke to reduce the effects of harmonics. It also employs ABB flux optimisation feature, making it more efficient than the previous drive.