Until recently it has been conventional practice to leave motors idling between duty cycles, but this is now seen as wasteful of energy - especially with increasing electricity prices.
"There was a sound engineering reason for doing this", explains Phillip Larkin
of Soft Start UK, one of the beneficiaries of the change of practice. "The wear and tear to the electrical and mechanical elements of a drive system at start up is quite considerable, so you were offsetting this against increased energy consumption."
But the growing emphasis on reducing carbon emissions has made plant engineers look again at many aspects of their businesses. Soft starts reduce the shock load and consequential damage by bringing a motor up to speed far more smoothly than direct on line starting.
Larkin says that it is very easy to make a financial case for installing a soft start on a large drive system, and so his company has seen a massive upswing in orders for medium voltage soft starts.
"For instance we are just completing a repeat order for a 6.6KV 1.2MW system for a Russian metal shredder, are building a 6.6KV 2.3MW four-motor multistart system for a pumping station at Gadansk in Poland, an 11KV 5.5MW system for out a dry dock pumps in Dubai and a 6.6KV MW explosion proof soft start for starting 3 off 670KW motors on Russian mining conveyer system".
And the trend is almost as pronounced in the smaller off-the-shelf soft starts. Larkin reports that sales of his 4KW-600kW units has quadrupled in less than 15 months. "This includes a couple of big call-off orders for OEMs, one off sales and ongoing projects where we are working our way through a plant to improve the energy efficiency of one machine after another."