EET

How to test occupancy sensors

The National Electrical Manufacturers Association (NEMA) has published a set of standards for testing room occupancy sensors that formerly were issued as guidelines.

Called the NEMA WD 7 Occupancy Motion Sensors Standard, it covers the definition and measurement of field-of-view and coverage characteristics that pertain to using vacancy and occupancy sensors which are making use of any combination of passive infrared, ultrasonic, or microwave technology. These sensors are used in systems for control of lighting, heating, ventilating, and air conditioning (HVAC), and other devices.

NEMA says the purpose of this standard is to promote uniformity for the definition and measurement of occupancy motion sensors, but is not intended to set performance levels.

A review of the standard reveals some interesting facts such as the use of a standard "test person" who must be at least 5 ft 3 in but no more than 5 ft 11 in. and weigh no more than 190 lb. The "test person" must also be able to move at a velocity of 4 ± 0.5 ft/sec with a two-second stop at the edge of each predefined measurement cell. There are also provisions for a minor motion test using a robotic arm measuring 3x3x15 in., mounted 36 ± 1 in. above the ground. The arm has to move at a velocity of 90˚/sec.

You can download a copy of the standard free here: http://www.nema.org/stds/wd7.cfm

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