While I have done research into Japan’s selection of HID ballasts, there was something that I find rather strange about their high wattage high voltage metal halide ballasts that really boggles my mind.

The thing that I find strange is that these high wattage metal halide ballasts have an OCV of only 300V, yet they are specifically designed for use with metal halide lamps that have an arc voltage drop of about 250V or so. Normally, I would expect that with such a low OCV, the lamps would normally cycle due to the insufficient supply voltage that they receive. Interestingly, those ballasts seem to be referred to as “peak progressive phase” ballasts.

Here is an example of one of those ballasts:

https://www.iwasaki.co.jp/lighting/support/products/detail.php?ItemNo=M10BLP2A60

Here are some lamps that are designed to specifically operate on this particular ballast:

https://www.iwasaki.co.jp/lighting/support/products/detail.php?ItemNo=M1000B%2FBU

https://www.iwasaki.co.jp/lighting/support/products/detail.php?ItemNo=MF1000B%2FBU

https://www.iwasaki.co.jp/lighting/support/products/detail.php?ItemNo=MT1000B%2FBH

I wonder why these metal halide ballasts were designed with an OCV that is so low that it is not much higher than the lamp’s arc voltage drop.

Here is some information about these ballasts:

https://www.iwasaki.co.jp/sources/hid_lamp/mh/multi_metal.html