scope:

This standard provides specifications for and operating characteristics of low frequency square wave electronic ballasts for metal halide lamps. Electronic ballasts are devices that use semiconductors to control lamp starting and operation. The ballasts operate from multiple supply sources of 600V maximum at a frequency of 60 hertz. The output frequency of electronic ballasts may be of some frequency other than 60 hertz. This standard only covers lamp operating current frequencies from greater than 60 hertz up to 400 hertz (some exclusionary frequency ranges may apply). An electronic square wave ballast is defined as an electronic ballast whose operating lamp current waveform is essentially a square wave with defined rise/fall times stated in the C78.43 lamp standards.