WILD FREQUENCY INFORMATION CENTER


As flight systems evolve from traditional hydraulic, to electrically-controlled/hydraulically powered, to electrically (or optically) controlled/electrically powered, one of the key design requirements for new power generation will be the ability to provide high-quality power at variable frequencies.  An equally important requirement will be for electrical equipment and systems to be able to utilize the wide variable frequency (or “Wild” frequency) of 350 to 800 Hz that is output by the variable frequency generators. In addition, ground support and test equipment capable of producing and handling “Wild” frequencies will be required.

 

Read the article in January 2007 Avionics magazine titled:

Perspectives: "Wild" Frequency must move toward wide acceptance

 

See the results of the survey:

Electrical Power trends in the military and civilian aircraft industry

 

Questions from readers with answers from our wild frequency experts

 

What exactly is wild frequency?

Mike T. MT

Wild frequency is the 350 to 800 Hz output from the variable frequency generator. This is a direct result of the aircraft engine speed. The variable speed is result of the takeoff and landing and in Military aircraft during combat maneuvers. Most of the time the engine produces 400 Hz.

 

I thought 400 Hz was the AC standard on all aircraft?

Jim W.  OH

400 Hz is the standard aircraft frequency in use today. To have a constant 400 Hz requires equipment that converts the varying engine speed to a constant 400 Hz. This adds weight, cost and maintenance. Using equipment that operates over the wild frequency will eliminate this extra equipment.

 

What will happen to all the existing avionics that are powered from 115VAC, 400Hz?

Peter R. NY

Since 400 Hz is still the standard most equipment will not have to operate from wild frequency. For aircraft that require wild frequency operation there are companies like Behlman that make frequency converters that can take the 350 to 800 Hz wild frequency and produce a fixed 400 Hz frequency.

 

Is there any equipment presently being manufactured that works at the wild frequency?

Gary V. PA

There is a number of product designed to operate from wild frequency. We have added a sampling of some of those product; flap actuator, data recorder, anti-collision light system, AC/DC module, control box, ice protection equipment. See items listed below.

 

Are there any MIL Specs for wild frequency requirements?

George B. CA

 

MIL-STD-704F references wild frequency under Table II. AC normal operation characteristics-variable frequency. There is also a commercial aerospace test specification for Radio Technical Commission For Aeronautics (RTCA/DO160) Section 16 which addresses the new variable frequency range of 360-800 Hz.

 

How could I verify if my equipment operates over the wild frequency?

Jack F. CA

Companies like Behlman manufacture frequency converters that can produce the 350 to 800 Hz variable frequency. This variable frequency can be used to power the UUT (unit under test) either manually by varying a potentiometer or encoders or via a remote control interface.

 

Information and products regarding wild frequency

 

High-Performance Front-End Converter for Avionics Application

This paper presents analysis, modeling, and design of a low-harmonic, isolated, active-clamped SEPIC rectifier for future avionics applications. Simpler converter dynamics, high switching frequency, zero-voltage-switching, and a single-layer transformer construction result in an efficiency of 90% and a very low harmonic distortion over 400-800 Hz line frequency variation.

 

Questions and answers on "Origin of 400 Hz in aircraft"?

 

Demonstration of Very High Power Airborne AC to DC Converter

This paper describes the challenges inherent in developing high power (>100kW) AC-DC converters for aerospace applications. Various technologies and topologies were considered, analyzed and rated, with an optimum design being chosen. Details regarding power quality, magnetics design, and thermal management are discussed. Performance results from demonstration hardware are provided, including power quality, regulation, efficiency (98%) and temperature results.

 

End of the circuit breaker: smart power makes its mark

Computer control of power distribution on aircraft and other integrated platforms is helping systems integrators improve reliability, safeguard sophisticated electronics from power spikes, and protect not only aircraft and other expensive military and aerospace systems, but also the men and women who operate them. An AIRINC 429 Tutorial

 

SAE AE-7 Committee Minutes 29 April-1 May 2003

SAE AE-7 5 year document review list. A 5-year review of AS 8023 is required. The committee needs to get a handle on which SAE documents are in active use. Only keep 5-year review for active document. Discussion on AS 1212 Electric Power Systems, Characteristics vs. MIL STD 704: 704 is accepted as is DO-160. Has AS 1212 lost its importance?...

 

Some questions about " MAGNESIUM OVERCAST- The story of the Convair B-36" by Dennis R. Jenkins

 

For members of IEEE

High-power variable frequency generator for large civil aircraft

Fault tolerant, variable, unity power factor converters for aircraft power systems

  

Converter enhanced variable frequency power bus architecture

 

Unity power factor power supply for use with variable frequency power

 

Aircraft power supply 400 Hz and beyond

 

The role of avionics in the all electric airplane

Available for purchase from the Electronic Library of AIAA

 

Personnel Licensing Advisory Circular

Aircraft Maintenance Technician Licenses Type Ratings

 

Goodrich On Board A400M

Airbus has selected Goodrich Corporation to supply the flap actuation package for its military transport aircraft,....

 

Data Recording Products

A wide range of data recording products with power test capability to 800 Hz

 

Anti-Collision Light System

Anti-collision light system based on LED technology that operates on 115 VAC form 360-800 Hz

 

Hi-Rel AC/DC Module

Active Power Factor Corrected over variable frequency 360-800 Hz

 

Airline Control Boxes

Can drive up to 10 standard actuators, up to 16 BUS actuators...power supply frequency 360-800 Hz

 

Ice Protection Systems

Products ranging from ice protection systems, both anti-icing and de-icing, to avionic systems and system monitoring equipment. Technologies include wild frequency.

 

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