Myth. Using soft-start equipment can cut demand charges.

Facts. The use of soft-start equipment can lead to savings, but it won't reduce the demand charge on your electricity bill. When a motor starts up, it draws a lot of current. This so-called inrush current is often five to six times the motor's full-load running current. All this current creates heat in the motor windings, and heat is what kills motors over time. As their name implies, soft-starters ramp up the voltage applied to motor terminals over time, thereby limiting the inrush current and power, which significantly reduces heat buildup. By doing so, soft-starters can extend motor lifetimes - particularly those of motors that are stopped and started frequently. In fact, with a soft-starter installed, you can turn a motor on and off much more frequently without worrying about damaging the windings. If your motor application involves an intermittent load, you may be able to save money by installing a softstarter and shutting the motor down in between loads rather than leaving it running continuously. But if inrush current and power are reduced, why can't soft-starters reduce demand charges? The answer has to do with how demand charge is typically calculated. The meter at your facility measures the average power you consume over each 15-minute period, and your demand charge is based on the maximum value of that average demand during your billing cycle. In contrast, a softstarter affects a motor's power draw over the course of just a few seconds. The reduction of the motor's power draw over that short period is insignificant in comparison to the time over which the demand charge is calculated. So although the soft starter has a substantial effect on instantaneous power demand, it has no noticeable effect on your demand charge.