IEC 61000-4-11: The Inrush Requirement That Disqualifies Most AC Sources

Standards & compliance · 3 min read · 21 cited facts

Voltage dip immunity looks like the least demanding test on a compliance schedule. Drop the supply for a defined number of cycles, see whether the equipment stays up. The levels are modest and the durations are short.

Then you read the generator requirements and discover why a general-purpose programmable source usually cannot run it.

The test levels

Parameter	Value	Clause
Dips, Class 2	0%/½ cycle, 0%/1 cycle, 70%/25 (50 Hz) or 30 (60 Hz) cycles	61000-4-11 Table 1
Dips, Class 3	adds 40%/10–12 cycles and 80%/250–300 cycles	61000-4-11 Table 1
Interruptions	0% for 250/300 cycles	61000-4-11 Table 2

Dips, interruptions and variations

The requirement that actually decides the instrument

Parameter	Value	Clause
Generator rise/fall	1–5 µs	61000-4-11 §6
Peak inrush drive	500 A (220–240 V) / 250 A (100–120 V)	61000-4-11 §6

Generator requirements

Edges in microseconds, not milliseconds

Rise and fall between one and five microseconds is far faster than most programmable sources slew. That is deliberate: the standard is describing what a real distribution fault looks like, and a gentle transition would let equipment ride through a disturbance it should not survive.

Phase-of-dip control changes the answer

Where in the AC cycle the dip begins materially alters what the device experiences — a dip starting at a voltage zero-crossing is a different event from one starting at the peak. The standard expects this to be controllable, which means it has to be a programmable parameter rather than whatever the source happened to do.

Above 16 A per phase you are in a different standard

IEC 61000-4-11 applies to equipment drawing up to 16 A per phase. Larger equipment falls under IEC 61000-4-34, which carries the same intent at a scale that changes the generator entirely. Confirm which one your product falls under before you specify anything, because the answer moves the budget.

Specifying a dip-immunity bench?

Tell us your equipment's per-phase current and class. The inrush requirement will decide most of the rest.

Talk to an engineer

IEC 61000 AC Immunity Testing