Sensors

Understanding How Sensors Work

The principle behind sensors for lighting control is the detection of specific environmental factors, such as movement or the amount of light. Depending on the application and the desired accuracy, various types of sensors are available.

How Motion Sensors Function

Motion sensors detect movement within a predefined detection area and subsequently activate a connected device, such as lighting. There are several detection techniques:

• PIR Sensors (Passive Infrared): These are the most commonly used motion sensors. A PIR sensor responds to changes in infrared radiation (heat) within its detection field, such as body heat from people or animals. When a temperature difference is detected between an object and its surroundings, an electrical signal is triggered. These sensors do not work through walls or glass.
• HF Sensors (High Frequency): These active sensors emit electromagnetic waves in the high-frequency range. These waves are reflected by objects and living beings. Movement is detected by a change in the frequency of the reflected waves, using the Doppler effect. HF sensors are independent of temperature and can detect through thin materials such as glass, wood, or plasterboard, making hidden installation possible.
• Ultrasonic Sensors: These sensors emit high-frequency sound waves and measure the reflection. Just like HF sensors, they respond to any movement, regardless of temperature, and can detect through certain materials.

Motion sensors can be set for range (how far the sensor detects), the time the light stays on after activation, and light sensitivity (at what dusk level the sensor becomes active).

How Dusk Switches Function

A dusk switch, also called a day-night sensor or light sensor, measures the amount of ambient light (lux). As soon as the light intensity drops below a preset level, the connected lighting is automatically switched on. When it gets lighter again, the lighting switches off automatically. This type of sensor is often used for street lighting, garden lighting, or advertising lighting.

The sensitivity of a dusk switch is often adjustable, so you can determine at which light intensity (expressed in lux) the light switches on or off. Many dusk switches also have an adjustable delay, so that brief changes in light (for example, due to lightning or car headlights) do not immediately cause the lights to be switched on or off unnecessarily.

Practical Applications of Sensors

Integrating motion sensors and dusk switches offers various benefits in different environments. These smart additions contribute to both comfort and functionality.

Lighting Control for Convenience and Energy Savings

• Outdoor Lighting: Sensors are commonly used for outdoor lighting, such as entrances, driveways, or backyards. A motion sensor switches on the lighting upon arrival or when unwanted visitors are detected, ensuring security and a welcoming appearance. A dusk switch ensures your garden lights switch on automatically at dusk and off at sunrise, contributing to a pleasant atmosphere without unnecessary energy consumption.
• Hallways and Storage Rooms: Indoors, motion sensors are suitable for spaces where constant light is not necessary, such as hallways, stairwells, basements, or storage rooms. The light switches on automatically when someone enters and off again when no movement is detected, saving energy and preventing unnecessary lighting.
• Public Spaces: In public buildings such as schools, offices, or warehouses, sensors ensure that lighting is only on when people are present, which leads to significant energy savings.

Sensors for Enhanced Safety

In addition to controlling lighting, sensors also contribute to the safety of a property.

• Burglar Prevention: Outdoor lights that switch on automatically upon detection of movement can deter potential intruders. Some sensors can also be connected to alarm systems.
• Orientation and Trip Prevention: Lighting for pathways and stairs using motion sensors reduces the risk of falling in the dark.

Key Considerations When Choosing and Installing Sensors

For a functional and long-lasting installation, several technical aspects need to be considered.

Selecting the Right Sensor

• IP Rating: For outdoor use, the IP rating (Ingress Protection) is very important. It indicates the level of protection against dust and water.
  • IP44: Splash-proof, suitable for sheltered outdoor locations.
  • IP54/IP55: Protected against dust and splashing water, suitable for most outdoor conditions.
  • IP65: Jet proof and completely dustproof, suitable for exposed locations and direct contact with water jets.
• Detection Range and Angle: These specifications determine the area that the sensor can cover. Pay attention to mounting height and the presence of obstructions that might affect the detection range. Sensors with a larger detection angle (e.g., 180° or 360°) are suitable for wider areas.
• Light Sensitivity (lux): Adjustable with dusk switches and some motion sensors. This determines at which ambient light value the sensor becomes active.
• Maximum Load: Always check the maximum switching capacity (in Watts) of the sensor to make sure it can switch the connected lighting.
• Power Supply: Sensors are available for mains power (230V) or battery-powered for wireless installations. The choice depends on the location and the availability of power outlets.

Practical Installation Questions and Solutions

Proper preparation is crucial for a successful installation. Below are common questions and their solutions.

How do I correctly connect a motion sensor to my outdoor lamp?

Connecting a motion sensor requires careful steps and a good understanding of electrical wiring. The most common connection involves three wires: live (brown), switched live (black), and neutral (blue), along with a ground wire (yellow/green) for safety.

1. Completely switch off the power to the relevant circuit in the fuse box to work safely. Use a voltage tester to check that the power is really off.
2. Determine the desired mounting location for the sensor. Take the detection range into account and avoid obstructions that could hinder operation.
3. Connect the brown live wire to the L terminal on the sensor. The black switched live, which goes to the lamp, is connected to the L1 terminal. The blue neutral wire goes to the N terminal on the sensor and the yellow/green ground wire to the grounding symbol.
4. Secure the sensor firmly to the wall. For outdoor sensors, ensure the wiring is finished to be watertight, for example with resin joints or suitable glands in a junction box.
5. After installation and checking all connections, the power can be switched back on. Test the sensor and set the desired parameters, such as light sensitivity and on-time duration.

What is the difference between a motion detector and a presence detector?

Although the technology is similar, motion detectors and presence detectors differ in sensitivity and application area.

• Motion Detector: Reacts to larger, clear movements. As soon as movement stops, the timer is reset and the light switches off after the set time. These are suitable for corridors, driveways, or outdoor areas where brief presence suffices.
• Presence Detector: These sensors are much more sensitive and pick up even the smallest movements, such as typing or turning a page. They are designed to monitor continuous presence and keep the light on as long as any movement is detected, even if it is minimal. Presence detectors are particularly suitable for offices, meeting rooms, or restrooms where people remain longer and with subtle movements.

Where should I install the sensor to avoid false alarms?

Correct placement is important to prevent unwanted activation (false alarms) and to ensure reliable operation.

• Avoid direct sunlight: Do not install sensors in direct sunlight, as sudden temperature changes in the sensor itself (for PIR) or rapid brightness changes (for dusk switches) can cause unnecessary activation.
• Keep away from heat sources: For PIR sensors, they should not be installed too close to heat sources such as air vents, air conditioners, or heaters, as temperature variations can trigger the sensor.
• Avoid obstacles: Make sure the detection area is free of obstacles such as trees, shrubs, flags, or cars, which can unintentionally activate or block the sensor.
• Optimal mounting height: Refer to the sensor's specifications for the recommended mounting height. This affects the effectiveness of the detection range and sensitivity. For outdoor sensors, a height of 2 to 3 meters is often recommended.

By taking these practical considerations into account during selection and installation, you create an effective and trouble-free automated lighting control system using sensors.