Issue link: https://te.mouser.com/i/1472769
AEROSPACE, DEFENSE & MARINE /// CONTACTORS FOR AEROSPACE GROW SMARTER AND MORE CAPABLE Page 1 by: Karl Kitts, Director of Development Engineering – High Performance Relays, TE Connectivity As a designer's primary choice to control high power circuits, contactors today offer more efficient operation and smarter operation to protect against overcurrent and faults. They are electrically controlled devices that use a low-power coil drive circuit to switch a higher power circuit. With the contactor located near the controlled load, this allows weight savings through use of smaller wiring sizes used for on/off coil control of the remote load. Contactors are a special high-power class of electrical relay designed to switch much higher currents and voltages. In a large commercial or military aircraft, contactors are used to control the different power sources, including engine-driven generators, auxiliary power units, batteries, external power, and ram air turbines. Power systems must not only accommodate the routine needs of flight, but also offer redundant backup power and emergency power. Switching high currents and voltages can certainly produce design and endurance life challenges for power contactors. Current spikes and arcing can damage both contactors and connected devices. Designers have devised various methods over the years to protect the contactors and connected circuits. Protection can include external elements such as shunting resistors, diodes, and transorbs. Today, transient protection is increasingly built into the contactor. The growth of high-voltage DC and AC systems also presents challenges for the power distribution components. Similar to issues surrounding 42 VDC automotive systems, designers cannot assume existing legacy relays and contactors are suited for use in these newer power systems. One of the most important trends today for military and aerospace contactors is building in more electronic intelligence to provide protection against abnormal events and to detect systems faults. Figure 1. Today's contactors bring smarter operation to power management. SWaP is Critical In aerospace and similar applications, designers are concerned with reducing SWaP—size, weight, and power consumption. Space is always at a premium, and weight savings translate in better fuel economy, longer flight times, and larger loads. Similarly, lowering power consumption throughout the power-generation and -distribution system can save weight and space. Considering a large commercial jet may now contain nearly 100 high-power contactors in the power distribution system, saving even 0.1 amp in control power for each device can be significant in overall power dissipation. Less power dissipation allows smaller power sources. In recent years, the aerospace industry has been moving away from traditional 28 VDC and 120 V/400 Hz power systems to 240 VAC and 270/540 VDC systems. These changes were required in order to supply the ever-increasing electrical demand, while minimizing the impact of weight from larger power feeders. From a CONTACTORS FOR AEROSPACE GROW SMARTER AND MORE CAPABLE