Confusing on Harmonic Emissions/Voltage Fluctuations/Flicker test for CISPR 11 Class A Equipment

[Joe Chen]

Hi Everyone,

I am confusing on weather Harmonic Emissions/Voltage Fluctuations/Flicker applies to a CISPR 11 Class A Equipment or not. According to the CISPR 11, Class A equipment is equipment NOT used in domestic establishments and NOT in establishments directly connected to a low voltage power supply network which supplies buildings used for domestic purposes.

According to IEC 61000-3-2 and IEC 61000-3-3, these two both apply to equipment rated <=16A and CONNECTED TO THE PUBLIC LOW VOLTAGE SUPPLY SYSTEMS, which means it only applies to CISPR 11 Class B equipment.

But when I checked with many medical equipment IFUs, I found that even for CISPR 11 Class A equipment, they do not mark "not applicable" in the harmonic emissions and voltage fluctuations/flicker emissions line in the Guidance and manufacturer's declaration - electromagnetic emission table. Can anybody help to explain why?

Thanks in advance,
Joe

 

[Peter Selvey]

Looks like you might be confusing "public" and "domestic".

"Public" is a broad area includes business, hospitals, clinics as well as domestic (normal house). Pretty much everything except a private system not connected to the supply network.

"Domestic" is non-business only, i.e. households.

Class B has stricter limits as a house is more likely to be located far away from signal towers. This means the strength of the "good" signals (phones, radio, TV etc) is likely to be weaker, so the interference from electrical devices needs to be quieter.

 

[Joe Chen]

Hi Peter,

Thanks a lot. I think that explains my confusing.

Thanks,
Joe