Types

There are several commercial available induction lamps in the lighting market nowadays. The development of induction lamps involve decades of effort in researches on relevant gas discharge physics, solid-state physics, material science and electronic ballasts.


The outcome is to bring the induction lighting concepts to engineering and to products in the commercial markets today. Advances in diverse technology fronts promise to drive down the cost and multiply the capabilities of microchips and photovoltaics, opening the way to new levels of performance and freedom of standard design practices.


For example, an electrodeless fluorescent induction lamp operates at 2.65 MHz with system power 55W and an efficacy of about 70 lm/W. The 2.65 MHz is specifically allocated in according to IEC regulations, for industrial application as radio frequency lighting devices. Lamps having the higher rating of 85W and 165W are also available for application where high intensity lighting is required. The lamp is filled with argon at 0.25 Torr. Mercury pressure is controlled by two amalgams:
one is for lamp starting, and
— the other maintain optimal mercury pressure over a wide range of ambient temperature.


The induction coil of the lamp is wound on a ferrite core and is housed within the lamp cavity. The ferrite core has an internal copper conductor rod connected to the lamp base for cooling of the induction cool and cavity. These lamps are driven by remote ballasts connected to the lamps by coaxial cables.


Another version of cavity induction lamp is designed to integrate the RF generating ballast into the lamp. This kind of induction lamp looks similar to a compact fluorescent lamp and could be used to directly replace an incandescent reflector lamp with much higher efficacy and longer service life.


The lamps operate at the same frequency of 2.65 MHz but have lower lamp power of 23W at 48 lm/W efficacy, and the lamp life is rated up to 15,000 hours. EMI is the major restriction of using these lamps in sensitive areas and significant efforts have been made for suppressing magnetic and electric components to comply with existing EMC regulations.


The cost of the lamp is over $50.00 at the moment and is relatively much higher than those of tungsten and compact fluorescent lamps.


In the external-coil induction lighting system the likeness to a standard transformer of this lamp is more apparent than for any other induction lamps. The lamp is made from a 54 mm diameter tube encircled by two closed ferrite cores. The lamp rating available are 15W~200W at an efficacy of up to 95 lm/W. The designed operating frequency is 250 kHz only, which is not governed by the radio frequencies allocated for industrial applications such as 2.65, 13.56, 27.12 and 40.68 MHz.


The decrease in working frequency has virtually eliminated EMI problems, ballast complexity, and cost as compared to other induction lamps working at 2.65 MHz. Due to the closed magnetic path of the ferrite cores, the power-transfer efficiency and efficacy of this lamp are extremely high; they are 98% and 95 lm/W respectively. The rated life of this induction lighting system is 100,000 hours, which is determined by the life of electronic ballast but not the lamp.


The high system efficiency is achieved by the distributed power deposition along the lamp in contrast with the cavity induction lamp where power transfer is localized around the coupling induction coil, causing local thermal stress and overheating that limits maximum lamp power.