DO-160 Section 17: The Spike Your Section 16 Source Cannot Make

Aviation & 400 Hz · 3 min read · 21 cited facts

Section 17 arrives on the same power leads as Section 16, in the same qualification programme, often in the same week of lab time. A programme that has just specified a programmable source for the Section 16 power-input conditions will reasonably assume the same instrument covers the spike test. It does not, and the reason sits in the waveform definition.

The categories and the waveform

Parameter	Value	Clause
Category A spike amplitude	E = 600 V, open circuit	Figure 17-1
Category B spike amplitude	2 × line voltage (AC RMS and/or DC) or 200 V, whichever is less, open circuit	Figure 17-1
Spike waveform	rise time ≤ 2 µs, total pulse duration ≥ 10 µs	Figure 17-1 Note
Generator source impedance	50 Ω nominal; verified into a 50 Ω ± 10 % load, which must halve the specified voltage ± 10 %	Figure 17-1

Section 17 spike definition — DO-160G

Category A covers equipment claiming a high degree of protection against damage by voltage spikes, at 600 V; Category B accepts a lower standard of protection, at twice line voltage or 200 V, whichever is less. Both amplitudes are open-circuit definitions — Figure 17-1 notes the peak may be substantially lower with the equipment connected, which is why the generator gets verified into a 50 Ω load that must halve the specified voltage.

A 600 V open-circuit spike rising in under 2 µs from a 50 Ω source is not a programmable-source waveform — no programmable AC or DC source slews at that speed. §17.3 permits any generation method whose output matches Figure 17-1; in practice that means a dedicated spike generator coupled into the power leads through a series injection transformer. Solar Electronics' datasheet for its 7054-2 spike generator, offered with impedance-matching transformers for Section 17 Categories A and B, shows the shape of the instrument this clause actually buys.

The application counts

Parameter	Value	Clause
Number of applications	minimum 50 positive-polarity spikes within one minute, then 50 negative within a separate minute, to each primary power input	§17.4
Mode coverage	test repeated for each operating mode or function of the equipment; same-bus power inputs tested simultaneously	§17.4

How many spikes, and where they go

On a box with several operating modes and several power inputs, §17.4 multiplies quickly: fifty spikes per polarity, per input, per mode. The spike generator does that arithmetic; the programmable source just has to keep regulating through all of it.

What Section 17 does not cover

Where the spike comes from — the standard defines the waveform, not the threat.
Lightning-induced transients, which belong to Section 22 with entirely different waveforms.
Power interruptions, sags and surges, which stay in Section 16.
Audio-frequency ripple on the bus, which belongs to Section 18.

Qualifying on the same leads for §16 and §17?

Tell us your bus, your Section 16 category and whether Section 17 Category A or B applies. We will scope the source for the power-input conditions — and say plainly that the spike generator is a separate line item.

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