Abstract
Numerous arbitrary test devices have been introduced which bump or vibrate a lamp to try to select suitable lamps for environments where shock and vibration are present; these devices in general are unsatisfactory. Failure due to vibration is usually caused by a component in the lamp being in resonance with a vibration frequency generated in the environment, which causes large magnifications of movement. A method of vibration testing and of presentation of results has been devised which enables the ‘vibration characteristics' of a lamp to be determined; with a knowledge of the frequency and severity of vibration encountered in its normal use, these two pieces of information can be integrated to give a formula for the ideal lamp. It is usually impractical to have the ideal design for any one service, but useful compromise designs can be made.
The lamp fitting can influence the severity and range of frequencies transmitted to the lamp, with useful or disasterous effects if a dangerous range of frequencies is attenuated or amplified; thus proper design of the fitting can make a valuable contribution to improving the life of lamps in rough-service applications. The complete solution is not just a stronger lamp; realistic test procedures, determination of exactly what a lamp must withstand, and the scientific design of both lamp and fitting are some of the aspects to be considered.
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