Just searched the message boards and there is a lot of contradicting information. I have heard of the following HPS lamp types, some of which have been claimed to have non-cycling behavior:
- Mercury Free HPS
- High xenon pressure HPS
- Unsaturated HPS
- Regular HPS

What are the characteristics of these lamps? Which ones cycle and which ones don't? How do I identify them?

All of the HPS street lights near me are mercury-blue colored when they first strike, but my Ignitron lamp is white when it strikes. So obviously there are at least two types of HPS that are distiguishable by startup behavior.

What are these lamps marketed as? I have heard of Philips Alto non-cycling HPS lamps, what category do they fall under? Never knew there were so many different types.

Are unsaturated lamps ever used outside of retrofit lamps?

Also do these lamps have anything to do with the whole HPS CWA compatibility mystery? (they say that saturated HPS retrofit lamps are incompatible with CWA MV ballasts, yet HPS CWA ballasts exist)

Thanks!

Mercury free HPS lamps can cycle, but rarely. Have much yellower color than standard HPS lamp.
High xenon pressure HPS lamps can cycle, but rarely. Runs up much faster than regular HPS lamp.
Unsaturated HPS lamps are the non-cycling HPS lamp. Runs up bluish mercury. have stable voltage over life.
Regular HPS lamps can cycle.
I think that European HPS lamps aren't compatible with CWA ballast for HPS lamps as well.

What color do regular HPS lamps start up with?

Purplish xenon color, and than LPS orange color.