Technical Bulletin

conditions. PIR increases immunity by inanimate motion in an unoccupied space. U/S transducers maximize

sensitivity to minor motion. Multi-technology utilizes the best of both to provide optimal energy savings. Adding

U/S technology to wall switch sensors assists with some of the challenges of having a sensor in these

traditionally troublesome locations. Wall switch locations can be blocked or located in out-of-the-way spots

which render PIR useless, multi-technology sensors can provide a better alternative for these blocked spaces

or irregular shaped rooms.

Flashing LED (False State Detection Circuitry)

Leviton sensors protect against false triggering the load (lights) ON or OFF (known as False ON or OFF). This

is verifiable through the use of indicator LEDs, Red LED signifies PIR technology sensing motion, Green LED

signifies U/S technology sensing motion. The LED flashes when the sensor receives a “significant” motion

signature and after detection, the relay will close. When the relay closes, there has been a "validation" of the

signal, which turns the load ON. This design is intended to prevent the load from turning ON when not needed

(False ON). Similarly, sensors attempt to screen areas of coverage to prevent false OFFs.

Leviton Advantage: Leviton Occupancy Sensors have extremely high payback margins but only because they

operate reliably. The LED flashing before “lights ON” is a visual indication that the false-detection algorithms

are actively screening out noise.

Vacancy Confirmation

Leviton multi-technology sensors keep both technologies sensitive after timeout expires. Lights are then

temporarily swept off while both technologies look for occupancy for an additional 30 seconds. If vacancy is

confirmed during this period, the sensor turns off until the PIR circuitry detects the next entry into the room.

Sensitivity Adjustment

Present on all sensors, it may take several forms depending on the model. A red knob, eye, or range would be

the PIR sensitivity and a green knob, or ear would be the U/S sensitivity. This sensitivity adjustment is for fine

tuning sensitivity within the general coverage area. The sensitivity adjustment may be used where false

triggering is occurring or for when the sensor is not detecting quickly enough.

Operational Variables

Temperature

The environmental temperature of an application will impact operation of passive infrared sensors. Traditional

PIR technology detects movement of a heat source between detection zones against a background of ambient

heat. In colder environments, PIR sensors will detect a heat signature more readily than in hotter

environments.

Air Movement

The air movement within a space can also create challenges for PIR and U/S technologies. With PIR the

movement of Hot or Cold air through the detection zones may falsely trigger the sensor and with U/S the air

movement can precipitate false triggering by alternating the reflectivity of the U/S feild.

Application Considerations

Coverage patterns should be staggered and overlapped to assure optimal coverage. Staggering the sensors

mounting location assures that moving objects will cross a detection zone. Overlapping coverage areas is a

good way to assure ample coverage.

Narrow aisles need special consideration. For example, a five foot wide aisle requires more sensors for most

reliable FOV detection. An object could move within the five feet and still be inside of a single detection zone,

and motion would not be sensed.