Thanks canyoncruz for your input, however, please could you give me a bit more clarity on these orders of difraction, how they affect the application of measuring light output from a luminaire. How could I calculate that I was in a nearfield and how can I calculate the real light output form the...
Thanks to Jghrist and Rbulsara for pointing out the missing frequency component. I am more familuar with capacitors marked in micro Farads from electronic PCB repairs and have not seen a VAR value. Could this possibly be the marking 47/99 on a 15 uF capacitor marked for 50-60 Hz? Also I am only...
I tried using this method as follows:
1. Calculate the VARs by taking the square root of the difference of the squares of the VA and Watt value.
2. Divide the square of the Volts by the VARs value to obtain the impedance.
3.The capacitor value for pf = 1.00 is supposed to be the reciprocal of...
I tried using this method as follows:
1. Calculate the VARs by taking the square root of the difference of the squares of the VA and Watt value.
2. Divide the square of the Volts by the VARs value to obtain the impedance.
3.The capacitor value for pf = 1.00 is supposed to be the reciprocal of...
The new flat screen computer monitors have a much lower glare than the old CRT types and seem to please our opperators plus take up less desk space, so lighting is not the only way.
Hello peebee,
Thanks for your reply. The terms I refer to are in the 9 th edition of the IESNA reference under the heading "Near Field" or from the index on near field.
I have not heard that illumination (Lux) was proportional to the inverse cube but certainly to the inverse square...
Current new electrical regulations in South Africa restrict the ratings of transformers for 12 V lighting systems to 200 VA. This is for fire and safety reasons. There is also an overload trip set for 1.6 times of this rating and an over temperature trip for 80 degrees Centigrade. I should...
With near-field there are apparently two types of measurements viz. Appliction-distance photometry and Luminance-field photometry. The first is still treated as a point source. I think this is what is confusing to me. Do you have experience with these measurements and calculations and does the...
I was recently sucessful with reducing glare by sticking tape to the edge of the flourescent fitting to allow light to shine down and not out on the cieling. This is simlar to specifying or useing louvres to direct light and reduce angles. Try also to place the work desk directly below and in...
Please could someone clarify what near field and far field photometry are and when they are appropriate. I am measuring luminaires and would like to understand what the differences are so I do not make erroneous reports.
Thanks for this site information. I have visited this previously but did not quite get what I wanted. I have, however, discovered the information in the IESNA nineth edition reference errata, available on their website in PDF format. This confirmed that there were errors in their origonal text...
115V circuits need a higher current to produce the same wattage as 240V and thus wiring must be thicker and fuses and circuit breakers heavier. 115V switches can have smaller dimentions as their arc gap is less.
I had dificulty accessing the Advance website to detirmine the exact flourecent type of your tube and ballast. There are three types of tubes in common use: rapid start, pre-heat and instant start. I suspect you have one of the first two types as the last type only has a single terminal on each...
Please could someone give me details of what exactly these standards are or where to find out their exact description. I seem to have come across very little on this and also some of it is conflicting and confusing.
