The "no blip" power supply

New industrial power sources handle current surges without tripping off. The result: No need to overspecify capacity. Here's what can happen when an ordinary power supply sees an inrush current as from a motor turning on: Temporary overloads can trigger the electronic protection circuits and trip the supply off. Supplies using what's called fold-back technology will cycle off, reset, and try to cycle on continuously as long as there's an overload. Clearly, inductive loads such as dc motors or solenoids won't start up properly when the power supply oscillates on and off. In addition, there can be other problems if these supplies trip too quickly in the presence of a genuine short circuit. Fast tripping can prevent secondary fuses from blowing, not good when a potentially hazardous condition exists. The typical way of heading off such difficulties is to specify a supply with enough capacity to handle turn-on current as part of its normal load. But this means the supply operates well below its rating for nominal output current most of the time. The expense associated with this unused capacity makes the approach uneconomical in this day and age of scarce resources. Power supplies built with an alternative