Areas investigated include: (1) load analysis; (2) power distribution, conversion techniques and generation; (3) design criteria and performance capabilities of hydraulic and pneumatic systems; (4) system control and protection methods; (5) component and heat transfer systems cooling; and (6) electrical system reliability

Brandner, J. J.

Lee, C. H.

English

NASA Technical Reports Server

July 1972	 B72-10383 
NASA TECH BRIEF 
Lewis Research Center 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Survey of Aircraft Electrical Power Systems 
An industry and literature survey has been made of 
the electrical power systems and equipment in present-
day commercial aircraft. Current practice and state-of-
the-art in aircraft electric power generation, trans-
formation, distribution, and utilization including present 
and projected electric loads was investigaged. 
The present aircraft electrical system (115/200-volt, 
3-phase, 400-Hz constant frequency ac) was developed 
about twenty-five years ago for the relatively small 
aircraft of that time. Many future aircraft are expected 
to require much more electrical power, at least part of 
which must be of very precise quality. Also, recent 
technical advances may outdate some of the equipment 
and concepts presently utilized in aircraft. This survey 
was conducted as an initial step in determining whether 
the present electrical system will be suitable for future 
aircraft. 
Specific areas investigated included the following: 
1. For electrical load analysis, electrical loads were 
classified and a weight analysis was made of the 
constant and variable frequency ac motors, and brush-
less dc motors. Parametric data for components were 
divided into components in existing aircraft, and cur-
rent technology components applicable to aircraft. 
The utilization weights were compared as a function 
of system electrical frequency (including dc). 
2. In the area of power distribution, design consider-
ations of safety, corona, voltage, and frequency levels 
were investigated. Characteristics and performance 
data on cables, relays, circuit breakers, contactors, 
and transformer-rectifier units were collected. Data 
for voltage and frequency effect on wiring weight 
were prepared. 
3. Power conversion techniques were considered and 
compared. Parametric weight data were obtained for 
the various possible techniques.
4. Possible methods of generating electric power were 
examined including: the present constant speed, con-
stant frequency (CSCF) system, and the variable 
speed, constant frequency (VSCF), rotating inverter 
and high-voltage dc systems under development. 
Analysis indicated that the more advanced generating 
concepts could offer performance advantages in com-
parison to the present CSCF systems while still re-
maining weight competitive. Parametric information 
on emergency power sources was also collected. 
5. The design criteria and performance capabilities of 
both the hydraulic and pneumatic systems were sur-
veyed since many aircraft loads, such as flight controls, 
landing gear, brakes, and thrust reversers, are presently 
serviced by hydraulic or pneumatic power. 
6. System control and protection methods in existing 
aircraft were reviewed and various protection schemes 
for single and parallel system operations were analyzed. 
7. Present techniques of cooling aircraft electrical com-
ponents and heat transfer systems were studied. 
Possible improvements in heat transfer methods uti-
lizing state-of-the-art technology were also considered. 
8. The objectives and criteria of aircraft electrical system 
reliability were outlined. The level of reliability cur-
rently achieved by various aircraft components and 
subsystem was also tabulated. 
Notes: 
1. The information obtained in this survey should be of 
interest to the electrical equipment industry. 
2. The following documentation may be obtained from: 
National Technical Information Service 
Springfield, Virginia 22151 
Single document price $3.00 
(or microfiche $0.95)
(continued overleaf) 
This document was prepared under the sponsorship of the National
	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States
	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States
	 will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19720000382 2020-03-17T03:37:39+00:00Z
Reference: NASA CR-i 10693 (N70-32344), 
Investigation and Development of New Concepts 
for Improvement of Aircraft Electrical Power 
Systems -- Interim Technical Report 
3. Technical questions may be directed to: 
Technology Utilization Officer 
Lewis Research Center 
21000 Brookpark Road 
Cleveland, Ohio 44135 
Reference: B72-10383
Patent status: 
No patent action is contemplated by NASA. 	 so' 
Source: C. H. Lee and J. J. Brandner of 
AiResearch Manufacturing Co. 
under contract to
Lewis Research Center
(LEW-1 1678) 
B72-10383	 Category 02


Survey of aircraft electrical power systems

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