Voltage surges or voltage spikes as they are sometimes called can shorten the life of any projection lamp. In some cases they can shorten lamp life by as much as fifty percent. If your projection lamps are only lasting a portion of what the manufacturer calls "The rated life" then you may want to consider using long Life Projection Lamps.
First you need to have a basic understanding of projection lamps and the typical voltages that they are exposed to in their every day life. We will begin with the term "Voltage Spikes".
Typically and according to electronic theory, the devices that you plug your house hold appliances into as well as your Audio Visual Equipment, are receiving 120VAC at 60 Hz. Now that's simple enough, and most of us are familiar with those voltages. But did you know that there are very few power stations that produce exactly 120VAC. Because of weather conditions, the condition of transmitting wires and other variables the voltage that you find at your outlet will not always be exactly 120VAC. In fact in some areas this voltage may swing from as much as plus or minus three or four volts. This is what we are referring to when we use the term "Voltage Spikes".
Projection lamp filaments are rated at a particular voltage rating, based on an average voltage that they will encounter over their life span. Yesterday's halogen lamps used 120VAC to operate, while today's halogen projection lamps generally operate on an 82 volt power supply. When the voltage exceeds the rated filament voltage it shortens the life of the projection lamp.
The long life projection lamp was developed to help reduce the cost of projection lamp failure due to voltage fluctuations. So how do Long Life Projection Lamps work?
The filaments of long life projection lamps are engineered to have a rating of five percent higher than standard projection lamps. These filaments are designed to handle the "Voltage Spikes" or power fluctuations that standard projection lamps can't. And in most cases, projection lamps that operate under lower than the manufacturer ratings will last longer as well.
Unfortunately there is a down side to all of this. Like anything else, when you do something to gain on one end, there is something you have to give up on the other. Changing the filament rating on projection lamps to a higher rating reduces the amount of light output, (lumens) they produce. In some cases as much as a thirty percent reduction in the light output. An example of this is the use of an 82 volt halogen lamp burning on 86 volts. The lamp would produce 14% more light, but with a life of only 70% of its rated life. This same lamp with a long life filament would produce less than 15% of its rated lumen output but with an increased lamp life of more than 25%.
In some cases the brightness (lumens) required for projection far outweigh the necessity to increase projection lamp life with the use of long life lamps. It becomes a matter of choice for each user as to what their priorities are when it comes to projecting their images and presentations.
Mark Boehm is the president of etbinc@comcast.net.
For more information on this subject: http://www.mbelectronics.com/view.aspx?id=299
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