Aircraft Electrical Power (DO-160) Testing

Overview 

RTCA, Inc. (Radio Technical Commission for Aeronautics), headquartered in Washington, D.C., is a non-profit organization that serves as a Federal Advisory Committee to the Federal Aviation Administration (FAA). Its recommendations form the foundation for many FAA policies, programs, and regulatory decisions.

Subcommittee SC-135 develops RTCA/DO-160, Environmental Conditions and Test Procedures for Airborne Equipment, the industry standard used by Boeing, Airbus, and other aircraft manufacturers to qualify avionics components and subsystems.

Section 16, Power Input introduces requirements for AC harmonic distortion and variable-frequency AC power systems.

• Section 16.5.1.8 defines AC voltage distortion testing.
• Section 16.7.1.2 defines AC current distortion testing.

These requirements apply to both single-phase and three-phase equipment and mandate voltage, current, and harmonic analysis for each phase. Aircraft electrical systems are organized into three categories:

• A(CF): Constant-frequency 400 Hz AC systems
• A(NF): Narrow variable-frequency (360–650 Hz) systems
• A(WF): Wide variable-frequency (360–800 Hz) systems

Testing requires measurement of harmonic magnitude (and optionally phase) across the applicable frequency band. DO-160 specifies analysis to 40 harmonic orders, while Boeing and Airbus often extend this to 50 orders. The Boeing 787 Power Quality Specification further expands this to 500 harmonic orders on fundamentals up to 800 Hz, and some OEM requirements call for spectrum analysis out to 150 kHz.

Solution

The Yokogawa precision Power Analyzers provide an excellent solution for making the required Voltage and Current measurements and harmonic analysis of magnitude and phase for each harmonic order.

The WT5000, PX8000 and WT1800R are capable of making THD and Harmonic Analysis up to 50 orders on fundamental frequencies of 800 Hz and higher.  Measurement accuracy and analysis functions meet or exceed the requirements outlined by the DO-160E test standard. Analysis capability up to 500 orders on an 800 Hz fundamental are available with Yokogawa’s Model WT5000 Power Analyzer.

Yokogawa Model WT5000 Power Analyzer

The Power Analyzer can provide complete power measurement functions on the avionic component, as required by DO-160E, such as the Voltage, Current, Real Power (W), Apparent Power (VA) Reactive Power (VAR), Power Factor and efficiency, over the operating frequency of the aircraft power system. The advantage of using the Power Analyzer is that both AC Power and Harmonic Analysis functions can be performed in one instrument. Also the Power Analyzer is designed for making high accuracy Current measurements which cannot easily be done with other types of harmonic analysis instruments.

Yokogawa can also provide precision high frequency Current Transformers with a wide band frequency response out to 150 kHz for applications requiring high current measurements.

Harmonic magnitude values for both Voltage and Current must be measured, and the Total Harmonic Distortion (THD) calculated, as well as the Individual Harmonic Content (Harmonic Distortion Factor %hdf) expressed as percentage of the fundamental. The Yokogawa Power Analyzers provide a numeric data display of each of the harmonic orders with magnitude and %hdf measurements.

Sample Numeric Display of the harmonic Voltage magnitudes and Individual Harmonic Content (hdf%) for each harmonic order out to 500 orders.

The below table provides a brief outline of the DO-160E requirements and the solution provided by the various Yokogawa Power Analyzers.

Conclusion

You must choose the proper type of test instrumentation to make accurate Current, Voltage and Power measurements, and AC Harmonic Distortion analysis on aircraft electrical systems and equipment, as defined by DO-160E, Airbus ABD0100.1.8, and Boeing B787 Power Quality Specifications.

Yokogawa precision power analyzers offer a measurement solution that will meet or exceed the industry test requirements and provide the following benefits:

• Ease of Use
• Measurements made Quickly, Conveniently & Accurately
• DC and AC Current, Voltage, Power and Harmonic measurements in one instrument
• Harmonic Analysis up to 500 Orders on 800 Hz fundamental to meet latest Boeing requirements
• Power Analyzers are covered by a 3-year warranty
• Full NIST and ISO17025 Traceable Calibration Services