`Our drives are smaller than yours`

A war of words has broken out between ABB and Siemens over whose variable speed drives are smaller. The dispute dates back to the launch of ABB`s new ACS 800 family of drives earlier this year, when ABB suggested that, not only were the new products much smaller than their predecessors, but also, in the case of a 160kW version, they were one eighth the size of an equivalent Siemens Masterdrive product.

Siemens has now hit back with the assertion that that some of its drives are, in fact, 86% smaller than their ABB counterparts.

According to Siemens Automation & Drives` marketing manager Ian Bowman, his company`s drives specialists got out their "rulers and measuring sticks" and the only way they could get close to ABB`s claimed figures was to compare the ABB drive with a Siemens Masterdrive module. This he suggests is "not really comparing apples with apples - more like apples with melons".

He says that a fairer comparison would be to compare the ACS800 with Siemens new MM440 drive. On an "apples for apples" comparison, he says Siemens 160kW drive is 24% smaller than the ABB version. "If we were to pick the comparison, we would go for the 1.1kW product where the MM440 is 86% smaller," he adds.

"If we want to compare cubicle sizes then many different parameter enter the equation - clearances top and bottom, and the ability to cope with higher ambient temperatures," Bowman continues. "This makes the comparison more difficult as size and cost become an issue."

He points out that cutting size also cut the motor capacity. "In some areas, the advantage goes to ABB," he concedes, "in others to Siemens".

"In the case of the 160kW drive, then the advantage on current capacity is certainly with Siemens," Bowman asserts.

No doubt, ABB will be getting out its own measuring sticks.