We have a goniophotometer that produces photometric data of our lighting fixtures. My question is will the test report of the gonio-photometer will differ if we use electronic ballast instead of inductance ballast.
Re: Using Electronic Ballast Instead of Inductance?
12/20/2011 7:55 AM
Yes I think it will, the electronic ballast will eliminate the strobe effect generated by the inductance ballast by raising the hertz from 50-60hz to 20k hz...There should be an efficacy improvement of ~10% , if your using fluorescent lighting...
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Re: Using Electronic Ballast Instead of Inductance?
12/20/2011 8:46 AM
If you're using a photometer to take measurements then you have to have a base value to work from. Changing the lamp driver is going to throw all previous readings out of the window. You're base value has gone.
You should stick to the manufacturers original specification.
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Re: Using Electronic Ballast Instead of Inductance?
12/20/2011 1:21 PM
Actually, the answer is both yes and no. There will be no difference in the color temperature so if your photometrics include color, you should see no change.
With respect to the electronic ballast, there are at least four versions of ballast for any lamp type. The "ballast factor" is a term that basically implies a fixed output level for a particular lamp type. It was developed as an energy savings option and it leads to lots of confusion.
On top of this, there are several choices of lamp type (power level) to choose from that adds another multiplier effect. Take for instance the standard 4 foot T8 fluorescent lamp. By design, it consumes 32 Watts provided that the coils are energized to keep the emitter hot. The emitter helps electrons jump from the wire into the gas envelop. This type of operation is called "hot cathode" and the applications consist of some form of "Rapid Start" circuit design.
"Cold Cathode" referrs to applications like "Instant Start" which provides a much higher open circuit voltage to start and keep the lamp going. An Instant Start ballast will run the same lamp (above) at 30 Watts, but the light output should be about the same.
Now, the 32 Watt lamp uses a buffer gas of Argon to keep the electrons bouncing around the gas envelop a bit longer, increasing the chance of photons being generated. By adding a little Krypton gas to the Argon, you lower the lamp wattage and you also cut back on the light output. This can be handy if you have more light fixtures than the space needs.
The same lamp mentioned above can be made with only Krypton gas as the buffer gas. In fact, four designs are commonly available in the same body.
For the 4 foot T8 lamp:
Rating % Argon / % Krypton
32W 100 % / 0%
30W 70 % / 30%
28W 30 % / 70%
25W 0 % / 100%
Then multiply times your electronic ballast factor and you get a percentage of the expected power consumption and light output.
I doubt that you will notice any change in the "blink" rate of the lamp. In a magnetic ballast, the lamp does extinguish and relight again at twice the power line frequency. But humans don't really notice that unless something is wrong with the lamp/circuit combination. The lamp voltage looks like this:
The spikes are called reignition spikes. Electronic ballasts don't produce these because the drive frequency is so high that the lamp voltage follows the drive voltage fairly closely at frequencies greater than 1000 Hz. Most electronic ballasts operate between 20KHz and 80KHz which makes the lamp look like a resistive load.
So, yes you will have to know a few things about the choices and how they will affect your light output. Call the manufacturer directly for more information.
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Re: Using Electronic Ballast Instead of Inductance?
12/21/2011 11:31 PM
Your goniophotometer will tell you the intensity of the light at the angle that the goniphotometer is set at. It is designed to tell you about the distribution of the light from the light fixture. Now electronic ballasts operate at a much higher frequency that the magnetic type. So, the quality of the light is the real factor. Magnetic ballests will give a strobe effect, especially if there are is moving equipment in your facility. Electronic ballests run at 20KHz or more. Your fluorescent tubes have a phosphorous material that actually produces the light. The phosphorous material has a persistance which you can observe if you turn the lights off and the room goes completely dark you will see the tubes glow a bit in the dark. This coupled with the high frequency of the electronic ballast will produce flicker free light.
The goniometer will tell you how well the light is distributed by the tube and the fixture reflector.
Run this test.... Set your meter on a given fixture and measure the light intensity and the power consumed by the fixture.
switch the ballest to an electronic one and measure the light again.
Do a comparison Cost - quality of the light --- Are additional considerations
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