Mitsubishi Heavy Industries Technical Review Vol. 48 No. 4 (December 2011)
51

Development of a High-Current Generator
to Comply with Aircraft Lightning Environments
and Related Test Waveforms

NOBUYUKI KAMIHARA*1

YUICHIRO KAMINO*2

The development of countermeasure of lightning protection for aircraft requires theproduction of high-current waveforms to comply with the Society of Automobile Engineers
Aerospace Recommended Practices (SAE ARP) 5412A – Aircraft Lightning Environment andRelated Test Waveforms,1 to simulate the current waveforms of lightning. Hence, to meet thisrequirement, Mitsubishi Heavy Industries Ltd. (MHI) developed a high-current generator thatconsists of three current generators and a control unit. The combination allows the simultaneous
application of the multiple waveforms that are required in a lightning protection test of a test
specimen. Furthermore, this generator enables to adjust the circuit constant while producing
waveforms that comply with SAE ARP 5412A to produce more specific test charge conditions. This
generator makes a major contribution to conduct the lightning protection tests in accommodatingwith the schedule of aircraft development in terms of lightning protection measures.

|1. Introduction
With changes in the regulations for commercial aircraft development, the validity of alllightning protection design must be confirmed by verification tests. This explosively increases thenumber of tests required and the need for an appropriable test facility.
Verification tests need to be conducted with simulated lightning currents, as prescribed in
SAE ARP 5412A. In addition, multiple current component waveforms must be applied to a test
specimen in a single discharge to produce a more natural lightning strike effect. Since no suchhigh-current generator is available in Japan, MHI developed the necessary generator and operates it
successfully. The sections that follow describe this generator.

|2. Outline of the high current generator
As prescribed in SAE APR 5412A, a simulated lightning current involves multiple current
component waveforms (Figure 1). Current component A, B, C, and D waveforms simulate the first
return stroke, intermediate current, continuing current, and subsequent return stroke, respectively.
The MHI high-current generator uses three current generators to produce these waveforms.
Table 1Component
A/D generator
Component Bgenerator
Component Cgenerator

Figure 1*1

Details of each component
generator
Dimensions (m)(W×L×H)

Switchingmethod

8.5×7.5×4.0

Gap switch

4.0×3.2×4.0

Ignitron switch

1.9×1.9×1.8

Semiconductor
switchSimulated current waveform

Research Department, Aerospace Systems*2

Chief Engineer, Machinery & Steel Infrastructure Systems

Mitsubishi Heavy Industries Technical Review Vol. 48 No. 4 (December 2011)
52

Changing the polar character of the applied voltage in each component generator makes it
possible to apply a simulated lightning current with both positive and negative electric charges. The
details of each component generator are shown in Table 1.
(1) Component A/D generator
The charge stored in the capacitor bank is applied to a test specimen by using a gapswitch. The peak current of the applied waveforms is 200 kA. The applied waveforms areadjusted by inserting an inductor (L) and resistor (R) in the generator circuit in series. One canswitch between the current component A and D waveforms by changing the circuit constant ofL and R. This generator is shown in Figure 2.
(2) Component B generator
The charge stored in the capacitor bank is applied to a test specimen by using an ignitronswitch. like the component A/D generator, an inductor and resistor are inserted in the generator
circuit in series to adjust the applied waveforms. The generator is shown in Figure 3.
(3) Component C generator
The charge stored in the capacitor bank is applied to a test specimen by using asemiconductor switch. This generator enables the precise setting of the time of application,
which had previously been impossible. The generator is shown in Figure 4.

Figure 2

Component A/D generator

Figure 3 Component B generator

Figure 4(4)Component C generator

Control unit
SAE ARP5412A defines complex waveforms, such as the Zone 1A, 1B, 2A, and 2B
waveforms, which are combinations of the current component A to D waveforms that depend
on where lightning strikes. In a verification test, each component waveform must be applied toa test specimen simultaneously in order to produce a more natural lightning strike effect.
The control unit detects the current waveform output by the component A/D generator,
and uses the detected signal as a trigger to switch on the component B and C generators in orderto produce the current component waveforms and apply them to the test specimen. This trigger
mechanism enables the application of a complex waveform to a test specimen.

Mitsubishi Heavy Industries Technical Review Vol. 48 No. 4 (December 2011)53|3. Results
MHI developed a high-current generator to apply waveforms that comply with SAE ARP
5412A. Figures 5 to 8 show the respective current component A to D waveforms as examples ofoutput from the generator. In each example waveform, the blue line represents the applied current
waveform and the red line represents the action integral (Figures 5 and 8) or the maximum charge(Figures 6 and 7). The action integral is the time integral of the square of the applied waveform
current and the maximum charge is the time integral of the current. The parameters of thesewaveforms satisfy the provisions of SAE ARP5412A. In addition, the different current component
waveforms can be applied to a test specimen simultaneously by using the control unit.
Furthermore, we can manage detailed test conditions, such as producing a reducing
waveform, by changing the circuit constant of each generator and precisely controlling the timethrough the component C generator.

Figure 5 Current component A waveform

Figure 6

Current component B waveform

Figure 7

Figure 8

Current component D waveform

Current component C waveform|4. Conclusion
MHI developed a high-current generator that complies with SAE ARP 5412A. The different
current component waveforms can be applied to a test specimen simultaneously by controlling eachcomponent generator from the control unit. In addition to comply with SAE ARP 5412A, it ispossible to produce the complicated waveform required for the tests by adjusting the circuit
constant of each generator to produce waveforms. As a result, we have more flexibility to manage
the detailed test conditions. The new high-current generator represents a considerable achievementin the development of the design of lightning protection for commercial aircraft.

References
1.

SAE ARP 5412A， Aircraft Lightning Environment and Related Test Waveforms， SAE InternationalGroup， February 2005