The international Zhaga consortium has published Book 3 that defines the interfaces for spotlight-type LED light engines, is now available on the Zhaga website. The current version is edition 1.2, and updated versions will be posted periodically.

Book 3 includes specifications for LED modules that are intended to be screwed to the heat-sink base of a luminaire by an OEM luminaire manufacturer, and to be controlled by separate electronic control gear.

The LLEs covered by Book 3 have a round disc-shaped aperture with a diameter between 9 mm and 23 mm.

The light output is essentially Lambertian, allowing the luminaire optics to have a defined input to shape the light distribution to the needs of the application.

An optional accessory included in this specification is a locking ring to allow screwless mounting of the LED module.