occupancy sensors

OCCUPANCY SENSORS

JHELUM RAY CHAUDHURI1ST YEAR (2ND SEM)DEPARTMENT OF IEE

JADAVPUR UNIVERSITY

POINTS TO DISCUSS

INTRODUCTION

TYPES OF OCCUPANCY

SENSORS

SENSOR TECHNOLOGIES

SOME SPECIAL CASES

Wall Switch

Wall Mount

Ceiling Mount

PIRUltrasound

Dual

ADVANTAGES OF OCCUPANCY SENSORS

DISADVANTAGES OF OCCUPANCY SENSORS

SELECTING AN OCCUPANCY SENSOR

APPLICATIONS

INTRODUCTION

OCCUPANCY SENSORS

• Automatically turns a light ON when motion is sensed and OFF when the room is unoccupied or after a set period of time.

• They may offer the option to switch the sensor from automatically turning the lights ON to requiring manual button press from the occupant (Manual/Vacancy Mode).

VACANCY SENSORS

• Lights have to be manually turned on, but will automatically turn off when the room is unoccupied for a predetermined period of time.

• A vacancy sensor does not offer an option of automatically turning the lights ON

TYPES OF OCCUPANCY SENSORS

Wall Switch

Ceiling Mount

Wall Mount

WALL SWITCH

When you don't want to install a separate device, choose this sensor because it replaces an existing wall switch.

Get both occupancy sensing and manual on/off switching in a single device.

Residential - basements, garages, laundry rooms, pantries, bathrooms, children's rooms, dining rooms, living rooms, family rooms and hallways.

Dual Technology

Passive Infrared Technology

CEILING-MOUNT

⋑ For 180° or 360° coverage of an area.

⋑ Preferred for better coverage of an area to keep obstructions (furniture/plants) from blocking the Wall Switch location.

⋑ Offices, garages, basements, dining rooms, living rooms, family rooms and hallways.

Dual Technology Passive Infrared Technology

Ultrasound Technology

Wireless Self-Powered

WALL MOUNT

For coverage of irregularly shaped areas or those with varying ceiling heights, as well as narrow hallway and high-bay corridor applications.

For detection in spaces outside the field of view of other occupancy sensors.

Adjustable swivel neck rotates 80° vertically and 60° horizontally to allow wall or ceiling mount installation.

Stairwells, hallways, basements and offices.

Dual Technology


SENSOR TECHNOLOGIES

• The design of the room and the amount of activity happening within the space will determine the level of sensitivity needed in the sensor.

• Occupancy Sensors are available in three distinct technologies, so that the occupant can be sure to find the appropriate solution for the space.


Ultrasound Technology

Dual Technology

PASSIVE INFRARED TECHNOLOGY

► Designed to detect motion from a heat-emitting source, PIR sensors switch lights On and Off when a person enters or exits their field of view.

OPERATING PRINCIPLE

► All objects with a temperature above absolute zero emit heat energy in the form of radiation.

► Usually this radiation is invisible to the human eye because it radiates at infrared wavelengths


OPERATION

An individual PIR sensor detects changes in the amount of infrared radiation impinging upon it, which varies depending on the temperature and surface characteristics of the objects in front of the sensor.

When an object, such as a human, passes in front of the background, such as a wall, the temperature at that point in the sensor's field of view will rise from room temperature to body temperature, and then back again.

The sensor converts the resulting change in the incoming infrared radiation into a change in the output voltage, and this triggers the detection.


ADVANTAGES Small size Reduced product price Passive detection system unlike the radar systems Relatively low power consumption Accurate detection in narrow areas with precision optics Compatible to work with microcontrollers Improved noise and external light interference resistance for

performance enhancement


DISDVANTAGES Long calibration time Specifically sensitive to thermal

radiation Unequally sensitive to various

distances of the detection range Insensitive to very slow motions or the

object (i.e. a body) in standing mode Wider sensor field view for lower

temperature range with distant object sensitivity

ULTRASOUND TECHNOLOGY

Ultrasonic sensors detect occupancy by emitting a high-frequency signal and interpreting changes in frequency as motion.

Ultrasonic sensors do not require a direct line of sight, meaning they can “see” around corners and objects.

They are also highly sensitive to motion – even minor hand movement.

ULTRASOUND TECHNOLOGY

Active motion sensors generate sound waves in the ultrasonic frequency range, typically around 30 to 50 kilohertz (kHz).

When no objects are moving in the area, the pattern of sound and the time it takes to bounce back remain the same.

If something moves, the detector senses that the level or phase of the returning sound waves has shifted slightly.

Passive Ultrasound Motion Detectors are also available which are triggered by the occurrence of sound waves due to occupancy.

DUAL TECHNOLOGY

Dual Tech sensors combine PIR and ultrasonic technology.

Lights are only activated when both sensors detect occupancy – eliminating false activation – and require one of the technologies to keep the lights on, significantly reducing the possibility of a false deactivation.

The dual technology system is rapidly gaining popularity among homeowners and businesses alike.

Ultrasonic Part

PIR Part

SOME SPECIAL CASES

WIRELESS OCCUPANCY SENSORS

• The Wireless Occupancy Sensors have built-in solar cells that draw on available ambient light to power themselves and can operate for up to 48 hours in total darkness.

• Batteries are not required for continuous operation, however batteries can be added as an option for applications without available ambient light.

DIMMING OCCUPANCY SENSORS

• The convenience of a sensor with the ability to adjust light levels through a built-in dimming control.

ADVANTAGES OF OCCUPANCY SENSORS

Can be very fool proof, allowing wide coverage and applications.

Can be wired to a dimming circuit to control room lighting based on available light and occupancy.

Small, inexpensive, and easy to install.

Can cover wide areas effectively; switching units can control a variety of equipment.

DISADVANTAGES OF OCCUPANCY SENSORS

▶ They can be more expensive (for small area applications), and may require more adjustments since sensors contain more than one sensing unit.

▶ Integrated Daylight Sensors can be difficult to adjust and require a dimming ballast or special wiring.

▶ Wall Switch Sensors’ range can be limited, and depending on the location of the switch, they can easily be obscured.

▶ Wall or Ceiling-Mounted Sensors tend to be more expensive and often necessitate rewiring.

SELECTING AN OCCUPANCY SENSORFor use in small, individual offices, the coverage area is not as

important as the feature requirements. Use the following criteria to select sensors:

Compatibility Daylight-Level Equipped Sensors Failure Mode Indicators Manual Controls Minimum Load Timer Settings Warranty Coverage

APPLICATIONS Bedroom

Drawing Room

Staircase

Office

Hotel Rooms