The appliance manufacturers had an effective lobbying campaign when the rules
were written!
Mike Violette
Washington Laboratories & American Certification Body
mi...@wll.com
+1 240 401 1388
On Aug 3, 2011, at 9:39 AM, Grace Lin wrote:
Dear Members,
Does anyone know the reason FCC exempts devices listed under FCC
§15.103(d) as quoted below?
“(d) A digital device utilized exclusively in an appliance, e.g.,
microwave over, dishwasher, clothes dryer, air conditioner (central or window),
etc.”
FCC KDB 772105 clarify the exempted household appliances:
“Exempt household appliances are electrical machines intended for
household tasks that assist persons in washing and drying clothes, household
cleaning, cooking, or food preparation; or is equipment that is directly
involved in conditioning the supply of household water and air (heating,
cooling and humidifying) in a residence. This includes appliances such as a
vacuum cleaner, washing machine, dishwasher, clothes dryer, air conditioner
(central or window), etc. This exemption is limited to basic housekeeping
appliances and is not intended to apply to all home-use products that may
contain digital logic.”
I wonder (and would like to learn from members) if the exemption is due
to the discontinous disturbance as stated in the EN 55014-1 (CISPR 14-1), the
emission requirements for household appliances in the EU.
I list several paragraphs excerpted from CISPR 14-1: 2005 for reference:
“Switching operations in thermostatically controlled appliances,
automatic programme controlled machines and other electrically controlled or
operated appliances generate discontinuous disturbance. The subjective effect
of discontinuous disturbance varies with repetition rate and amplitude in audio
and video presentation. Therefore distinction is made between various kinds of
discontinuous disturbance. “(CISPR 14-1 Clause 4.2)
“The limits for discontinuous disturbance depend mainly on the
character of the disturbance and on the click rate N ....” (CISPR 14-1 Clause
4.2.1)
“For discontinuous disturbance, the click limit Lq is attained by
increasing the relevant limit L (as given in 4.1.1) with:
44 dB for N<0.2, or
20 lg (30/N) dB for 0.2≤N<30
“
Thank you very much for your time and look forward to your comments.
Best regards,
Grace Lin
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