Twilight sensor included in luminaire?

Yes.

A twilight sensor, also known as a photocell or light sensor, is included in luminaires (light fixtures) to provide automatic control of the lighting based on ambient light levels. The primary purpose of a twilight sensor is to save energy by turning on the luminaire when it's dark and turning it off when there's sufficient natural light available.

Here's how it works:

• Detection of Ambient Light: The twilight sensor is equipped with a light-sensitive element that can detect the amount of ambient light in its surroundings. This element might be a photodiode or a phototransistor.
• Threshold Setting: The luminaire's twilight sensor is typically set to a specific light threshold. This threshold determines when the twilight sensor considers it dark enough to activate the light. This setting is adjustable in some systems, allowing you to customize the sensitivity.
• Automatic Control: Once the ambient light level falls below the set threshold (indicating that it's getting dark), the twilight sensor triggers the luminaire to turn on. This is particularly useful for outdoor lighting, such as streetlights or garden lights, as it ensures that they are only active during the hours of darkness.
• Energy Efficiency: During daylight hours, when there's enough natural light available, the twilight sensor prevents the luminaire from turning on. This energy-efficient feature helps to reduce electricity consumption and extend the lifespan of the light source.
• Dusk-to-Dawn Lighting: Luminaires equipped with twilight sensors are often referred to as "dusk-to-dawn" lights, as they automatically adjust their operation based on the changing light levels at sunset and sunrise.

In summary, including a twilight sensor in a luminaire enables the light fixture to automatically respond to changing ambient light conditions, improving energy efficiency and providing convenient and adaptive lighting control.