China manufacturer of magnetic ballasts for metal halide flood lights & hps flood lights

Metal halide lamps have two basic configurations; those with an outer envelope and those without. In the former, the lamp’s basic construction is an inner envelope (called the arc tube), which contains the arc, and an outer envelope (called the bulb) which filters out ultraviolet radiation (UVR) and shields the inner arc tube. These lamps are typically single-ended (SE) and use a threaded mount to screw into a socket. The second lamp configuration lacks the outer envelope and typically has two ends (double-ended, DE) that need to be inserted into a socket, as we shall discuss shortly.

Metal-halide lamps have high luminous efficacy of around 75 – 100 lumens per watt,about twice the efficiency of mercury vapor lights and 3 to 5 times that of incandescent lights,[moderately long bulb life (6,000 to 15,000 hours)[ and produce an intense white light. As one of the most efficient sources of high CRI white light, metal halides are the fastest growing segment of the lighting industry.[1] They are used for wide area overhead lighting of commercial, industrial, and public spaces, such as parking lots, sports arenas, factories, and retail stores, as well as residential security lighting and automotive lighting.

Starting the lamp: In MH lamps, ballasts provide the starting voltage and ignition pulses (pulse-start lamps) necessary to ignite the lamp. Probe-start MH ballasts, however, can take as long as 10 to 20 minutes to restrike (re-start) a lamp. Pulse-start MH ballasts can restrike the lamp within 2 to 8 minutes of an interruption in current, because they provide high-voltage pulses to start these lamps.

Regulating lamp current and power: The ballast regulates the lamp operating current flowing through the lamp after the lamp has been started. The ballast is set to deliver relatively stable power to the lamp while regulating the lamp current despite typical line voltage fluctuations. This maximizes lamp life and ensures other performance characteristics such as color and light output.

Providing appropriate sustaining voltage: MH ballasts must maintain suitable voltage and current wave shape to the lamp. MH lamp voltage typically increases over time, and the ballast must continue to provide sufficient voltage to the lamp as it ages. In addition, the American National Standards Institute (ANSI) and/or the lamp manufacturers specify a suitable current wave shape to the lamp to achieve good lumen maintenance. Lamp current crest factor (CCF) is defined by ANSI as the ratio of the peak value of lamp current to the root-mean-square value of the current. A low CCF (between 1.4 and 1.6) contributes to good lamp lumen maintenance and longer life.

The inner arc tube contains the electrodes and various metal halides, along with mercury and inert gases that make up the mix. The typical halides used are some combination of sodium, thallium, indium, scandium and dysprosium iodides. These iodides control the lamp’s spectral power distribution and provide color balance by combining the spectra of the various iodides used.