This article from Softstart explains why soft starters are being specified on equipment for which they were previously not being considered.
Soft starts are being installed at an unprecedented rated so plant operators can save energy by stopping intermittent-duty motors when they are not in use. 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 electrical prices.
Philip Larkin of Softstart UK says: "There was a sound engineering reason for doing this. 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, so his company has seen a substantial increase 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; we are building a 6.6kV 2.3MW four-motor multistart system for a pumping station at Gdansk in Poland; an 11kV 5.5MW system for dry dock pumps in Dubai; we have also just delivered a 6.6kV 1.4MW explosion-proof soft start for starting three 670kW motors on a Russian mining conveyor system."
And the trend is almost as pronounced in the market for smaller off-the-shelf soft starts. Larkin reports that sales of his 4-600kW 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."
