Solid State Power Controller Technology

Advanced electrical power systems proposed for new platforms such as the More Electric Aircraft (MEA) require the use of electrical load management systems. A load management system is used to allow the aircraft power system to make critical decisions as to which loads at any given time are mission critical, flight critical, and non-critical. This removes a difficult responsibility from the pilot thus enabling the pilot to stay focused on actually flying the aircraft. A critical technology required to implement an electrical load management system is the Solid State Power Controller (SSPC). SSPCs are intelligent switching devices which have the ability to sense current and are programmable to trip and or current limit according to a current versus time curve. SSPCs can be electronically commanded either manually or by a microprocessor and are also able to be electrically reset after sensing and reacting to a fault condition thus enabling the SSPC to clear nuisance trips. The solid state nature of these devices implies no moving parts thus increasing lifetimes by orders of magnitude over equivalent electromechanical switches which in turn improves power system reliability. Moreover, advanced power systems proposed for MEA are considering the use of 270 VDC power as opposed to conventional 400 Hz power. 270 DC power is more difficult to switch than conventional 400 Hz because of arcing associated with DC switching. Solid state devices are desirable for this type of switching because they are able to perform arcless switching faster than electromechanical relay can switch DC and extinguish the arc internal to the device.