Recommended Maintenance to Increase Your Lamp Life!
In order to get more hours out of these high powered lamps, a few maintenance issues need to be addressed. This article will go over both double-ended and single-ended lamps, although the causes of failure are very similar between the two.
A common problem that occurs to double-ended lamps is the cable and lug turning blue and black. This is due to a very poor connection between the surface of the lug and the electrical post. The poor connection is usually caused by the washer and lock-nut/wing-nut that is used to secure the lug to the electrical post becoming loose. You should tighten these connections with pliers or a wrench the first day that they are installed. After 12 to 24 hours of operation these connections should be re-tightened. I have found that after this amount of time I can unscrew these wing-nuts/lock-nuts with my fingers. This is inherent with most of the12K and 18K DE fixtures of very high current.
Many different metals with varying expansion rates are used in the lamp and fixture; copper, nickel, aluminum, stainless steel and even low grade iron. This varying expansion is the main cause of the connections becoming loose. A loose high-voltage connection creates tremendous heat with temperatures reaching between 450 and 500 degrees C. Such extreme temperatures cause the lug, cable and eventually the metal base to oxidize, turning blue and black. The oxidation further hinders the electrical connection, creating more unnecessary heat, and eventually causing the lamp to fail.
In order to increase the temperature resistance of our lamps, we use cable that is 27% nickel plated copper. The lug is the same. The base is nickel plated brass and the weld is silver and copper. All these materials are very resistant to extreme heat but remember, the lamp is rated at 280 degrees C max. As are all double-ended lamps. The ribbons and moly pins that are inside the base of our lamps operate in air. When they are exposed to that extreme temperature and current the electrical connection between the two will disintegrate. The result is the arc-out as you may have seen. So it is imperative that the electrical connection be kept clean and tight.
Another problem that we sometimes see is corroded, melted, or pitted pins on single-ended lamps. This is caused by a poor electrical connection and can be prevented by setting up a simple cleaning procedure when your lamp fixtures come back to you. Purchase a hand drill with a wire brush extension and also a small flashlight/maglite. While your maintenance people are cleaning the fixtures, have them clean the high voltage contacts inside the sockets with the hand drill/wire brush combo. Then use emery cloth/sandpaper to clean the brass pins on the lamp. Doing this will ensure a proper electrical connection between the socket and the lamp and help to prevent overheating. Remember, you are only removing the oxidation on these parts, not enlarging the socket or reducing the diameter of the pin. If any pitting or worn areas are visible on the contacts, these contacts should be replaced. As with the double-ended lamps, the goal is to maintain proper electrical contact, reduce overheating and oxidation, thus increasing the life of the lamp. This procedure should also be implemented for your 12K through 24K tungsten fixtures and lamps.
Here at Wolfram, we clean all electrical contacts weekly and replace all high-voltage contacts every twelve months as a general maintenance procedure. This happens with all Par fixtures. It is necessary preventive maintenance, and cheap insurance.