Lighting Circuit Current
Lighting Circuit Current
(OP)
Hi,
Just wondering if anyone could help me with calculating the current that should be running in a typical HPSV Lighting circuit. (teach me how to read the data sheet)
Considering a 400W lamp - Magnetic Ballast - Ignitor - P.F.Capacitor
Should I sum all the power loss + 400W.
Do I need to consider the current drawn by the P.F Capacitor?
Anywhere on the WWW I can read up on this?
Thanks
Just wondering if anyone could help me with calculating the current that should be running in a typical HPSV Lighting circuit. (teach me how to read the data sheet)
Considering a 400W lamp - Magnetic Ballast - Ignitor - P.F.Capacitor
Should I sum all the power loss + 400W.
Do I need to consider the current drawn by the P.F Capacitor?
Anywhere on the WWW I can read up on this?
Thanks





RE: Lighting Circuit Current
Summing Watts out and losses will give you the total watts but will not infer the current.
You may also have reactive currents. With cheaper ballasts you may expect greater reactive currents. The capacitor may not be correcting the power factor to unity.
respectfully
RE: Lighting Circuit Current
I guess it is implied that the ballast line current would be covering the lamps and P.F correction capacitor?
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Looking at a data sheet from phillips BSN40L407ITS. The current listed would it be inclusive with the P.F correction as no indication on this... I assume that with this we can basically ignore the data on the lamps that is attached assuming appropriate types?
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Unfortunately there do not seem to be any current listed on the datasheet I have. Only
Lamp
Wattage (W) 400
Operating voltage (V) 100
Operating lamp current (A) 4.4
Max. starting current (A) 8.5
Ballast
Nominal wattage 400
Losses (W) 36
Impedance (W) 46
Resistance (W) 0.95 ± 0.10
Inductance (H) 0.15
Power factor before correction 0.42
Power factor after correction 0.99
Capacitor used 45uF
I just realized that they put Resistance & impedence in W so back to excel...
Would be grateful on advice to use this. At work everyone uses "rule of thumb" 1.8 x Lamp Power to get the Apparent Power for design assumptions. I'm trying to verify this.
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Merry Holidays and a Happy New Year!
RE: Lighting Circuit Current
It is not possible to do so. What happened is that the greek letter "omega" got translated to "W". It happens now and then. The reason is that little omega looks like "w" - only more rounded shape - and somewhere inside Gates' brainchild has got confused with any character looking like it. Which happened to be "W".
Also, I cannot understand why you say "Unfortunately there do not seem to be any current listed on the datasheet I have". There is both operating current and maximum starting current. Go easy with your Excel sheets. Get an understanding before applying automation.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Lighting Circuit Current
Operating lamp current (A) 4.4A X 1.8 = 7.92A The 8.5A is not far off the rule of thumb figure.
I suggest using the current that is given (8.5A) and accepting that the rule off thumb verifies it as reasonable.
Thanks for the explanation, Gunnar. I was wondering about those units.
Respectfully
RE: Lighting Circuit Current
I'm not quite sure what you are really looking for. If you are just interested in the current requirements for a particular HPS light fixture, just use the normal current input for the corresponding ballast. You can forget about the lamp - it gets all of its current from the ballast.
Any ballast supplier should be able to give you this information. It will take into account power factor, ballast losses, etc.
RE: Lighting Circuit Current
thanks, dpc, I was suspecting that it should be base on the ballast's as well but not sure if the value already considered the correction or not and as Waross point out we should really be looking at the staring current.