Inverters and converters

Abstract

The advantages of lamp operation on higher frequencies than 50 or 60 Hz have already been pointed out in Section 8.8. These advantages are: smaller ballasts with lower losses, a higher lamp efficiency and a negligible luminous ripple. Several attempts have been made to make use of these advantages in practice. This is not too difficult in the case of installations for which some form of inversion is needed anyway, as for example where only a low voltage d.c. supply is available. A d.c.–a.c. inverter can then be employed to provide the optimum value of output frequency. Values between 100 Hz and 25 kHz are in use; the higher frequencies exploit more fully the possibilities referred to above, but are more difficult to achieve with a high inversion efficiency. For installations operating from the normal 50 or 60 Hz power supplies it is more difficult to obtain favourable results. The necessity of an a.c.–d.c. converter, introducing higher investments and appreciable losses, in most instances more than counterbalances the possible gain.