[Tech1] LED rant.

[Chris Woolf]

On 27/02/2021 14:49, dick via Tech1 wrote:
> Don't forget the poor power factor of LEDs.  Not a problem now but 
> when electricity companies start taking it in to consideration (which 
> they can with a smart meter)  the cost of running your LED lighting 
> will go up by a factor of 10.
> ....


Typical LED drivers aren't that bad - most are up around 0.85 which is 
perfectly acceptable for non-resistive loads. You could argue an 
increase of 20%, certainly not 10 times!

Power factor is a problem for almost all modern equipment that uses 
sophisticated (and therefore reactive) power circuitry. TVs and computer 
monitors are notorious - frequently ~ 0.5. Many fluorescent lamps were 
about as bad as that, though better versions might be nearer 0.9.  
Electric motors, particularly under light load, are also poor - 0.7 - 0.85.

Ideally supply companies would like PF to be >0.9 but I suspect they all 
recognise that virtually every home is using reactive electrical loads 
nowadays and so simply up the unit price to take that into account. The 
greater problem is unbalancing 3 phase supplies, nasty harmonics and in 
some case having a wrong rating for overload equipment.

Any modern digital meter is perfectly capable of taking power factor 
into account. It is only old-fashioned induction motor types that can't 
do that, so smart meters give no more of a risk of higher charges. If 
they ever get round to using smart meters properly then those ~without~ 
them will lose out for variable rate charging.

Chris Woolf


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