Avionics News June 2013 - 21

tronic cockpit systems, power management
remains rooted largely in analog-era technology – circuit breakers, with some advantages and economy over fuses.
Well, at least for most Part 23 certificated
aircraft.
Waiting in the wings, so to speak, is the
solid-state circuit-management system,
complete with electronic circuit breakers
and a host of protections and features unmatched by analog-age circuit protectors.
Modern power-management hardware
is already becoming established in Part 25
business-turbine and commercial aircraft,
with ever more employing digital circuitry
protections and controls for their sophisticated flight-deck and back-cabin electronics systems.
Sources for the technology are expanding in both certificated and experimental
aviation.
Astronics Corp., for example, supplies
a variety of solid-state circuit switching,
intelligent power management and distributed architecture products used in businessturbine and commercial aircraft.
The world of certificated aircraft is seeing the migration start. In one example,
Airbus’ upcoming A350 employs modern
electrical-power management, as does very
light jet maker Eclipse Aerospace in the
company’s Eclipse 550.
“Digital electrical power distribution,” as
Eclipse labels its approach, is representative
of the company’s total-integration philosophy for the Eclipse. The VLJ employs electronic circuit breaker technology and smart
power distribution with electrical power
automatically controlled and distributed by
the aircraft’s Avio Processing Center – the
central brain of the jet’s avionics, power
and aircraft-systems management package.
The glass cockpit is the perfect environment for emerging approach to electricalpower management.
Experimental aircraft operators already enjoy alternatives to the busses-

and-breakers system of wiring control.
Ditto for the light-sport aircraft market,
in which World Aircraft Company, a manufacturer of light-sport aircraft, is one of the
latest to embrace ECBs and electronicpower-management system for its Spirit,
Vision, Freedom and Surveyor models.
Many other LSA makers already embrace
the approach, while others are coming
around.
Those inroads would seem to set the
stage for the day when electronic-power
management nudges circuit breakers into
the company of Venturis and pump-based

Waiting in the wings, so
to speak, is the solid-state
circuit-management system,
complete with electronic
circuit breakers and a host
of protections and features
unmatched by analog-age
circuit protectors.

air-powered instruments and electrical fuses in the evolution of power-management
protection and control for the majority of
general aviation.
Absent approved products, however,
circuit breakers still dominate light general
aviation aircraft, even as those aircraft’s
panels move ever deeper into the digital
age.
The Current State of Electrical-Power
Management: Busses, Breakers and
Lots of Wire
As an avionics technician once explained to me, the more complex the panel
installation, the more devices and the more

breakers the ship needs. Add standby or
emergency power generation – or a battery – and complexity can increase as the
technician wires the plane for the secondary
power source while simultaneously isolating the two sources and providing standby
power to a select list of gear… a PFD and
one nav/comm or GPS, for example, plus a
transponder or other ADS-B Out transmitter.
More wires, more breakers, more complexity – and more weight, more failure
points and more prospective maintenance
needs.
All those wires and breakers – or thermal-mechanical electric-limiting devices –
suffer with age and use, eventually becoming maintenance items of their own.
While the emergence of digital electronics has helped avionics makers pack more
into less space, electrical-power distribution
and protection largely remains unchanged
in most aircraft.
But the advances in electronics, electronic switching and digital logic open the way
to electrical systems simpler to create, and
more reliable and flexible in their ability to
handle functions beyond circuit protection
and switching.
The specialized field effect transistor
serves as a switching device and can be
adapted to a current-limiting device. The
most common type of FET in switching
circuits is the “metal oxide semiconductor
field effect transistor,” or MOSFET.
In a nutshell, this advance allows for the
fundamental functions we count on from
circuit breakers plus significantly more –
but without breakers or most of their functional limitations.
Here is how Michael Ballas and Fred
Potter, both of Astronics Corp., explained
it in their SAE International technical paper, available online at http://papers.sae.
org/2012-01-2183/, titled “Advanced AirContinued on following page

avionics news

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june

2013

http://www.papers.sae.org/2012-01-2183/ http://www.papers.sae.org/2012-01-2183/

Avionics News June 2013

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