Hello from San Diego:
Fred Waechter asks:
> Table 3 - Limits for Class D Equipment, has two columns for the limits,
> one is maximum harmonic current per watt and the other is maximum
> permissible harmonic current. The two columns don't appear to agree.
True.
At 600 watts, the mA per watt limit is almost always less than
the maximum permissible limit. There is a step-discontinuity.
This was done intentionally. However, I cannot give you the
rationale.
(The maximum permissible limits are the same as for Class A.)
For example:
At 600 watts, the 3, 7, 9 and 11 harmonic current limits
make a step up from the mA/W limit to the absolute limit.
At 600 watts, the 5th harmonic current limit matches the
maximum permissible limit.
The requirements are more lenient for power just over 600 watts
and more stringent for power just under 600 watts.
Best regards,
Rich
