CLD Controls and Dimming 4

Question 1

What is 'lamp flicker' in the context of dimmed LED luminaires, and which metric quantifies it?

Accepted Answer

Rapid, periodic variation in light output, measured by Percent Flicker or Flicker Index

Answer

Flicker is a rapid variation in light output; Percent Flicker and Flicker Index are the primary metrics used to quantify its severity and potential health impact.

Question 2

A designer notices that LEDs start 'dropping out' (turning off suddenly) before reaching the desired minimum dim level. What is the most likely cause?

Accepted Answer

The LED driver's minimum dimming threshold is higher than the control signal's target level

Answer

Every LED driver has a minimum controllable dim level; when commanded below that threshold, it drops out rather than continuing to dim, requiring a driver with a lower minimum dim point.

Question 3

Which phenomenon causes LED color temperature to shift toward warmer hues as they are dimmed, intentionally mimicking incandescent behavior?

Accepted Answer

Warm Dimming

Answer

Warm dimming is a feature in certain LED products that shifts CCT from a cooler value at full output to a warmer value (e.g., 1800K) at low dim levels, simulating incandescent dimming behavior.

Question 4

A lighting control system uses 'load shed' functionality. What does this feature do during a demand response event?

Accepted Answer

Reduces lighting levels or turns off non-essential fixtures to lower peak electrical demand

Answer

Load shedding reduces or extinguishes non-critical lighting loads in response to utility demand response signals or local peak demand thresholds, lowering energy consumption at critical times.

Question 5

What is the purpose of a 'soft start' feature in a dimmer or LED driver?

Accepted Answer

To ramp light output up gradually from zero rather than switching on abruptly at full power

Answer

Soft start gradually ramps the light output from off to the set level over a brief period, avoiding the visual shock of instant full-brightness switching and reducing mechanical stress on components.

(CLD) Certified Lighting Designer Practice Test

(CLD) Certified Lighting Designer Practice Test

CLD Controls and Dimming 4