Testing avionics & aircraft equipment to MIL-STD-461G CS101
MIL-STD-461G CS101 is not a test of whether the equipment functions. It is a test of whether it can be upset — disturbance is injected deliberately onto the power leads and the equipment is watched for any change in behaviour. The subject here is avionics LRUs, ground power units, aircraft actuators and converters, running on 115/200 V 400 Hz AC, 28 VDC, 270 VDC, and the qualification being chased is that the box keeps working when the aircraft bus misbehaves. What decides it is audio-frequency ripple injection, not anything the supply does at nominal. 400 Hz waveform synthesis belongs to a different document. Two things are needed: the injection chain, and series ripple injection across 30 Hz to 150 kHz via a coupling transformer, driven either by a signal generator and power amplifier chain or by a programmable source with built-in ripple and interharmonic injection. The EUT's own supply must be clean and fed through 50 µH LISNs, sized to the platform power type.
What you are testing
- Device under test
- avionics LRUs, ground power units, aircraft actuators and converters
- Bus
- 115/200 V 400 Hz AC, 28 VDC, 270 VDC
- Who buys this
- airframe and avionics suppliers qualifying to a platform spec
What MIL-STD-461G CS101 does not cover
- 400 Hz waveform synthesis
- reliability duration testing
- grid ride-through
- automotive voltage classes
If your programme needs those, they come from a different standard and often different hardware.
The limits this test has to reproduce
The 400 Hz bus is the whole game here, and the transient envelopes are what separate a source that can run this test from one that merely reaches the voltage.
| Parameter | Value | Clause |
|---|---|---|
| Frequency range | 30 Hz – 150 kHz | CS101 |
| Applicability | AC inputs ≤30 A per phase and all DC inputs | CS101 |
| Limit Curve #1 | 136 dBµV (≈6.3 V RMS) for nominal source voltage above 28 V | CS101 Figure |
| Roll-off at 150 kHz | 106.5 dBµV (Curve #1) / 96.5 dBµV (Curve #2) | CS101 Figure |
| EUT power feed | Through 50 µH LISNs | §4.3.6 |
The clauses aviation programmes actually face, as published in MIL-STD-461G CS101, revision G, 11 December 2015. See every limit in MIL-STD-461G CS101. Certification work should be run against the published standard.
What decides the rig here
The requirements that separate a system that can run this programme from one that only meets the headline numbers.
Peak, not RMS, sizes the source
The transient envelope reaches well above nominal. A source rated only on steady-state RMS will clip the surge and the test is invalid before it starts.
Frequency has to move, not just sit
Variable-frequency platforms need programmable df/dt, and a fixed-400 Hz source cannot run those clauses at all.
The DC bus is a second test programme
28 V and 270 V clauses are a separate rig from the AC work. Programmes routinely budget for one and discover the other late.
Other standards this DUT usually faces
Further reading on MIL-STD-461G CS101
Send us the clauses you have to satisfy
We will come back with the source and load capability that covers them — and tell you plainly if something in your spec needs hardware we would not supply.
Talk to an engineer