CLD Controls and Dimming 2

Question 1

Which dimming protocol uses a two-wire digital bus to individually address up to 64 devices per segment?

Accepted Answer

DALI

Answer

DALI (Digital Addressable Lighting Interface) supports up to 64 individually addressable devices on a single two-wire bus segment.

Question 2

Forward-phase (leading-edge) dimming is best suited for which type of load?

Accepted Answer

Magnetic low-voltage transformers

Answer

Forward-phase (leading-edge) dimming was designed for magnetic low-voltage transformers and resistive loads, not electronic or capacitive loads.

Question 3

In a 0-10V dimming system, what light output does a 0V control signal typically produce?

Accepted Answer

Minimum dimmed output (≈1-10%)

Answer

A 0V signal in a 0-10V system drives the fixture to its minimum dim level, not completely off; a separate switch is needed to cut power.

Question 4

What is the primary advantage of reverse-phase (trailing-edge) dimming over forward-phase dimming for LED loads?

Accepted Answer

Softer turn-on reduces inrush current and audible noise

Answer

Reverse-phase (trailing-edge) dimming cuts power at the end of each half-cycle, reducing inrush current and minimizing audible buzz common with LED and electronic drivers.

Question 5

A lighting designer specifies a scene-based control system. Which feature distinguishes a 'scene' from a simple on/off switch?

Accepted Answer

Scenes store preset level combinations for multiple zones simultaneously

Answer

A scene stores and recalls preset dimming levels for multiple zones at once, allowing complex lighting environments to be activated with a single button press.

(CLD) Certified Lighting Designer Practice Test

(CLD) Certified Lighting Designer Practice Test

CLD Controls and Dimming 2