0-10V dimmers work in different ways depending on the application.
When used to directly control a lighting fixture, the switch within the device will apply or cut power directly to the load. The violet and gray dimmer lead wires provide a signal between 0-10V to the ballast/driver on the lighting fixture, instructing it to dim to a certain percentage.
These dimmers can also be used in conjunction with a power pack (OPP20). Power packs have a higher rating than the 0-10V dimmers and can be used in applications where the number of fixtures exceeds the product rating. Power packs can also be used when incorporating a 0-10V dimmer into a 0-10V lighting system (including occupancy sensors or daylight sensors, etc.). In this application, the switch within the device will apply or cut a signal to the power pack, instructing it to turn the lighting fixture on or off. The violet and gray dimmer lead wires provide the same 0-10V signal to the lighting fixture in these applications.