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Electrical and Safety standards for Offline SMPS

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cupoftea

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Hi,
The following questions pertain to how to pass the EN Electrical & Safety standards for offline SMPS...

1…Supposing an offline PSU (comprising an offline SMPS with Vout <42.4V) supplys a Household, handheld consumer product (which is connected to the PSU via a cable) which presents a highly transient load. (Sudden full load to no load transients, and vice versa). Peak power 300W, average power 150W.
a)….Does the EN61000-3-2 mains harmonics emissions testing take place with the normal transient load, or with a steady constant load?
b)….Does the EN55011 mains conducted emissions testing take place with the normal transient load, or with a steady constant load?
c)… b)….Does the EN55032 Radiated emissions testing take place with the normal transient load, or with a steady constant load?

2….1…Supposing an 150W offline PSU (comprising an offline SMPS with Vout <42.4V) supplys a Household , handheld consumer product, which is connected to the PSU via a cable…
a)….Must the PSU be IP67 rated?, ie, immune to being submersed in water for 30 seconds.?
b)….Or, to what IP rating must it conform?

3…Supposing an offline 150W PSU (comprising an offline SMPS with Vout <42.4V) supplys a Household , handheld consumer product, (which is connected to the PSU via a cable)…
a)….Is the outer casing of the PSU allowed to be metal?
b)…If it is allowed to be metal, what is the maximum temperature allowed at the surface of the metal enclosure?

4…Supposing an 150W offline PSU (comprising an offline SMPS with Vout <42.4V) supplys a Household , handheld consumer product, (which is connected to the PSU via a cable) and is encased in a totally-sealed plastic enclosure to IP67….
a)…Is it actually possible for such a PSU to pass EN55032 Radiated Emissions compliance testing if it doesn’t contain a metal plate lining, or metal foil lining, within that PSU’s plastic outer casing?….the lining may have “Gaps”, so can be like a “net” structure.

5…Supposing an offline 150W PSU (comprising an offline SMPS with Vout <42.4V) supplys a Household , handheld consumer product, (which is connected to the PSU via a cable)…
a)…Suppose that the cable between PSU and handheld product is not shielded, is there any chance that that product could still pass Radiated Emissions compliance testing to EN55032?

6…Supposing an offline, non-isolated SMPS comprises a single diode rectifier. The SMPS is a 17W Buck converter using LNK3902, with 24Vout…The neutral forms the entire ground of the entire Buck circuit, there is no impedance in this ground (ie, there is no inductor, resistor , or ferrite bead in this ground). The neutral is fed right through from mains input, to Buck output as the ground of the whole circuit. This buck supplies a microcontroller and some other circuitry such as 15W BLDC driver.
a)….Is it impossible for such a circuit to ever pass Conducted immunity testing to EN61000-4-6, because it comprises no impedance in its ground circuit (Neutral is the ground)
b)….Is it impossible for this circuit to pass ESD immunity to EN61000-4-2 because it comprises no impedance in its ground circuit? (Neutral is the ground)
c)….Is it impossible for this circuit to ever pass conducted emissions testing to EN standards, since it has no common mode choke, and no Y capacitors.

7….1…Supposing an 150W offline PSU (comprising an offline SMPS with Vout <42.4V) supplys a Household , handheld consumer product, which is connected to the PSU via a cable…
a)…During conducted emissions testing, the handheld product will be wrapped in earthed metal foil, to simulate its use with a human holding it. As such, common mode emissions will be far worse. As such, do you agree, the power supply concerned would far more easily pass this conducted EMC test , if the mains earth cable is connected to the SMPS PCB?....Because then, y capacitors could be connected to this earth and make a Common mode filter to filter out the extra common mode noise.
 

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