Can we avoid PFC regulations by splitting the loads up?

[eem2am]

Hello,

We are currently designing an offline Power Factor Corrected Flyback for 53W of maximum output power.

This is for a temperature controlled , two outlet shower (head and body jets). The hot and cold water flow is controller by stepper motor valves.
(total 4 stepper motors).

Everything on the secondary side is an isolated load.

The loads are:
4 stepper motors (10W each)
80 LEDs (total 5W)
4 normally-closed solenoids. (2W each)


Would i be right in saying that , instead of using one 54W Power Factor Corrected offline SMPS, we can simply use.........

one 40W (non-PFC) offline SMPS for the stepper motors
and
one (non-PFC) 13W offline SMPS for the solenoids and LEDs.


New laws mean PFC is essential for loads above 50W, but can we avoid PFC converters by simply splitting our loads up into 2 loads, each less than 50W?

 

[FvM]

I assume, that EMC rules apply for the device, not for the building blocks. Doesn't it have common power terminals?

 

[mtwieg]

You'd probably only get away with it if they were completely independent devices with separate power connections, power converters, and enclosures (with maybe some data link between them). Also they would probably need to be sold separately to be considered individual systems.

 

[Genomerics]

You might do well to check the appropriate regulations rather than accepting the 50W baseline as is.

I am not 'current', by a long way, but last time I heard the requirement for PFC came in bands A, B, C and D depending on the application.

You might find that in your case the requirement does not exist or it is relaxed to the extent that you can achieve the required 'limits' with a much simpler circuit without going for a 'full blown' SMPS PFC solution and the headaches that might create.



Having recently opened up my PC power supply, apparently worth 350W but I am talking old kit, I can 'assure' you that 'Power Factor Correction' as such just involves the suggested 'lump of iron', AKA a low frequency, and cheap, inductor.

I may be wrong but you need to read the regulations to see what you can get away with.

Genome.