Here is an extract from the Wiki on Power Factor limits for Classes A to D.

https://en.wikipedia.org/wiki/IEC_EN_61000-3-2

I'll mention only ClassA which is contained in the first two columns.

According to the Wiki, PF is required for loads that draw more than 75W and for this table have a phase current of <16A.

For n = 2 the ClassA harmonic current limit is 1.08A

For n = 3 the ClassA harmonic current limit is 2.3A

For n = 4 the ClassA harmonic current limit is 0.43A

Does this mean that the current drawn for each harmonic must be below those limits?

And if your PSU draws less than 16Arms then it would only need PFC if any one or more of those harmonic current limits were exceeded?

To me those limits seem pretty lax?

Am I understanding this correctly?

https://en.wikipedia.org/wiki/IEC_EN_61000-3-2

I'll mention only ClassA which is contained in the first two columns.

This table of limits extends to the 39th harmonicLimit lines

Harmonic order Current limit

. . Class A . . . Class B . . . Class C . . . .Class D

n . . .[A] . . . . . . . [A] . Expressed as percentage of the input current [%] Permissible current per watt [mA/W] PermissibleHarmonicCurrent A

2 . . . 1.08 . . . . . 1,62 . . . . 2 . . . – . . . . –

3 . . . 2.3 . . . . . .3,45 . . . .3*λ . 3.4 . . . 2.3

4 . . . 0.43 . . . . . 0,64 . . . . – . . . – . . . . .–

According to the Wiki, PF is required for loads that draw more than 75W and for this table have a phase current of <16A.

For n = 2 the ClassA harmonic current limit is 1.08A

For n = 3 the ClassA harmonic current limit is 2.3A

For n = 4 the ClassA harmonic current limit is 0.43A

Does this mean that the current drawn for each harmonic must be below those limits?

And if your PSU draws less than 16Arms then it would only need PFC if any one or more of those harmonic current limits were exceeded?

To me those limits seem pretty lax?

Am I understanding this correctly?

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