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R

robsparx

Hi all

Can anyone tell me what the limits for harmonic current emissions are for lighting in bs en 61000?

I've asked a manufacturer for a figure for the THD for light fittings they sell, and they've replied with a statement saying that their lighting meets bs en 61000-3-2 limits for harmonic current emissions, but I have no idea what these limits are!

Thanks

Rob
 
You know, I never thought of that! Much cheaper than paying £90 for a bleeding book

Thanks
 
Im pretty certain its 30% THD, i have the info somewhere. Electronic ballast are normeally <10%, so no issues there, if you struggle for info, ring tridonic or philips they will sort you out.

Cheers
 
>25W input power:

3rd harmonic: (30 x power factor)% (percentage of fundamental)
5th harmonic: 10% of fundamental. Goes down from there.

The rules for <= 25W are more complicated...
 
Thanks for the info guys

I'm trying to calculate the cable for size for a sub main supply to a DB dedicated to high mast floodlighting ( 2000W HID lamps with magnetic ballasts). Well, I'm checking calculations as an exercise for my own benefit really (I'm out of practice with cable calcs). The job has already been designed by someone else

I'm awaiting info from the manufacturers, so in the meantime I estimated a 0.9 power factor and 20% THD. Does that sound about right?

Thanks

Rob
 
Thanks for the info guys

I'm trying to calculate the cable for size for a sub main supply to a DB dedicated to high mast floodlighting ( 2000W HID lamps with magnetic ballasts). Well, I'm checking calculations as an exercise for my own benefit really (I'm out of practice with cable calcs). The job has already been designed by someone else

I'm awaiting info from the manufacturers, so in the meantime I estimated a 0.9 power factor and 20% THD. Does that sound about right?

Thanks

Rob

You are probably best working to a factor of 1.5 for magnetic ballast, that will take into account control gear losses, PF and harmonic's.

Cheers
 
Hi Geoff,
your assumption of .9 pf is correct..
THD would be 30% of fundamental..

For sizing fuses and subsequently cables these 2 items are not really of any concern..

what you need to ascertain in order to carry out calculations are as follows;

1..The size of the pf capacitor.
2.. Current due to rectification.
3.. The starting current
The above values will be available from the manufacturer
 
Hi Geoff,
your assumption of .9 pf is correct..
THD would be 30% of fundamental..

For sizing fuses and subsequently cables these 2 items are not really of any concern..

what you need to ascertain in order to carry out calculations are as follows;

1..The size of the pf capacitor.
2.. Current due to rectification.
3.. The starting current
The above values will be available from the manufacturer

They are of every concern, PF and harmonics increase the current drawn, so the CPD and cables need to be sized accordingly.

But as you say, you also need to consider inrush currents.

Cheers
 
What I meant is that due to them complying with THD emissions and PF being as high as .9 they are of no real concern..

The 3 items I mentioned are the main factors for determining OCPD
 
Would it be an idea to split the load up, and then have seperate switches for each contactor coil, and or make use of some delay timers so the inrush is a little kinder on the supply and the DNO? Also with 70 Kw of magnetic balasts have you considered the spike on the supply when the main protection device opens under load, or even the spike at that poor contactor. Hint V =L (quite high) *Di/Dt (could be VERY HIGH)?
 

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