TRIDONIC.ATCO | Lamps

These lamps are used in a wide variety of applications.

Most types will strike quite easily down to -30 °C using conventional control gear. A cooling down period of approximately 5 minutes is required before reignition is possible.

No ignitor is required for starting high-pressure mercury lamps. In order to achieve the performance values, 3 basic types of choke are offered and tapped versions which can be adjusted to various supply voltages are also available. With the aid of power tappings on the chokes, e.g. OMB 125/80, and the TridonicAtco power transfer switch, high-pressure mercury lamps can be dimmed in steps to 50 % of the standard output.

Metal halide lamps are similar in construction to high-pressure mercury lamps but special additions to the gas composition have produced a much better colour rendering and better efficiency.

The good performance values of metal halide lamps make the lamp more difficult to start so that an ignitor is required. Metal halide lamps are extremely sensitive to variations in supply voltage; even slight increases in voltage can have an adverse effect on lamp life while greater undervoltage can visibly affect colour rendering. For this reason, TridonicAtco’s standard range only includes chokes with several voltage tappings.

Experience with metal halide lamps has shown that in some cases, the so-called rectifier effect will come into effect at the end of life – the discharge lamp only operates in one direction and therefore functions as a rectifier. High DC current flows can then rise to up to three times the nominal current which causes the choke and ignitor to overheat. This safety risk has already been taken into account in the lighting standard. Since September 2002, it is prohibited to sell light fittings containing lamps with these characteristics. Further information on which particular lamps will be affected by this can be obtained from the lamp manufacturer or from TridonicAtco. By using a thermal cut-out in the choke, the temperature is permanently limited to a permissible maximum. This catalogue only lists chokes with thermal cut-out (marked TP or W).

Like metal halide lamps, high-pressure sodium lamps require high voltage for ignition which is normally produced by an ignitor although some lamps also have built-in ignitors. At present, the most common type of ignitor is the superimposed-pulse ignitor which does not use the choke to produce high voltages. However, if an impulse ignitor is used, the chokes are loaded with high voltage and must be capable of withstanding this. TridonicAtco chokes over 70 W are designed for use only with superimposed-pulse ignitors as standard.

High-pressure sodium lamps can also function as a rectifier at the end of life. For this reason, only chokes with thermal cut-out are again specified as chokes for these lamps within the standard TridonicAtco range.

A high-pressure sodium lamp with outstanding colour rendering properties can be created by changing the gas mixture although luminous efficacy will be reduced. A hybrid device is required for operation – a conventional choke in conjunction with an electronic control package which keeps the colour temperature constant.

There is no evidence that these lamps function as rectifiers at the end of life and therefore a choke with thermal-cut is not required.