Class II Div II Hazardous Environment Occupancy Sensor Project Specifications First Edition 10/23/2012

Joint ECE (Team 166) and ME (Team 26) Senior Design ECE 4901/ME 4972 Fall 2012 Advisors Sung Yeul Park (EE), George Lykotrafitis (ME)

Sponsored By:

Contact: David Behnke ([email protected])

Computer Engineering Christopher Zannoni

Electrical Engineering Christopher Zannoni Joanne Hitchcock Gledi Progonati

Engineering Physics Russell Gee

Mechanical Engineering Michael Gazda James Fisher

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Introduction Project Purpose Used appropriately, occupancy sensors save electricity, extend component lifetime, provide a safer working environment, and ultimately provide extensive cost savings. Sensor Switch uses infrared sensing technology to build industry leading occupancy sensors that can be used in a multitude of commercial, residential and industrial environments. However, special considerations must be made in environments in which hazardous conditions exist. In an effort to create safer working conditions and minimize damaging accidents, the Occupational Safety and Health Administration (OSHA) has classified potentially dangerous environments according to the potential threat of explosions due to atmospheric gas and dust. Without proper safety precautions, electrical devices, including equipment such as occupancy sensors, can ignite an explosion that pose a serious threat to not just equipment, but human life as well. Our goal is to design an occupancy sensor that can operate in a hazardous Class II Division 2 environment. Project Description An occupancy sensor, originally designed by Sensor Switch, will be modified to operate safely in a Class II Division 2 hazardous environment. Such an environment is defined by the National Electric code (NEC) as having the potential for explosive dust clouds being created due to mishandling or accidents. Also it should be noted that the IEC hazardous area classification of Zone 22 matches the previous requirement, however this was not mentioned by the sponsor we should be aware of this classification. Zone 22 is defined as a place in which an explosive atmosphere, in the form of a cloud of combustible dust in air, is not likely to occur in normal operation but, if it does occur, will persist for a short period only. For example, leaks from incorrectly fitted lids or spillages. The relay shall be protected from the environment in some manor, isolating the potentially explosive switch from the dust source. Furthermore, the occupancy sensor itself will be analyzed and potentially modified to assure the electronics are inherently safe. Last, the occupancy sensor must be able to communicate with the relay, either wirelessly or by a direct connection.

Cost Specifications and Limitations Sensor switch place a cost limitation on the project. They indicated the total cost of the device[product sale price and product installation cost] must be low enough such that it would cost the consumer less to purchase this device than the savings realized due to a decrease in energy consumption over the course of three years using the device. The calculation for this value is as follows: The supplied Sensor Switch CM 10 occupancy sensor can cover, on average, about 2400 square feet1, with fluorescent light fixtures on average consuming about 1 watt per square foot2 we can calculate that one sensor controls 2.4 kW worth of lights. With the average US cost per kWh of $0.10/kWh in 20123 and using a figure of 3000 hours/year a facility operates4 one 1

http://www.sensorswitch.com/OnlineCatalog.aspx?sn=cm%2010 http://www.gelighting.com/LightingWeb/na/resources/tools/lighting-assistant-toolkit/lighting-layoutestimator.jsp 3 http://www.eia.gov/electricity/monthly/pdf/epm.pdf 4 57hours/week from: http://infohouse.p2ric.org/ref/32/31316.pdf 2

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occupancy sensor controls $720/year worth of electricity. Storage areas or warehouses would be a good example a division 2 area5. According to a U.S. EPA Prediction6 a storage area is occupied 45%-80% of the time. Using this percentage, one sensor would save $144-$396 per year in electricity costs if the lights were on 100% of the operating time without a sensor. Using the 3 year constraint mentioned earlier the cost of the sensor, relay and installation, cannot be more than $432-$1188.

Regulations Related to Project that Drive Specifications: The largest part of our project specifications come from hazardous location regulations. Below are the specifications from various hazardous location regulations that pertain to our project

NEC 2011 Regulations: Article 500: Hazardous (Classified) Locations, Classes I, II, III, Divisions 1 and 2 500.5 Classifications of Locations Class II, Division 2. A Class II, Division 2 location is a location:  Where combustible dust may be present in the air in quantities that can produce explosive or ignitable mixtures  Where combustible dust accumulations are present but there is not enough dust to interfere with the operation of electrical equipment, but it could interfere with operation of equipment if there is mishandling of equipment and the dust becomes suspended in the air.  Where combustible dust accumulates near electrical equipment it can interfere with the safe dissipation of heat from electrical equipment, or there could be an ignitable failure of electrical equipment. 500.6 Material Groups Class II Group Classifications  Group E. Atmospheres containing combustible metal dusts, including aluminum, magnesium, and their commercial alloys, or other combustible dusts whose 5

Understanding Hazardous Area Sensing-Intrinsic Safety, handbook by Bob Svacina and Brad Larson found at: http://www.parrinst.com/wp-content/uploads/downloads/2011/06/SvacinaLarson_Understanding-Hazardous-Area-Sensing_Intrinsic-Safety.pdf 6 Although the actual report could not be found, this number is used throughout the industry. Additionally we did find a study by a member of the EPA ENERGY STAR Buildings Program, Bill VonNeida, who referenced that this number. The report is found here: http://www.lrc.rpi.edu/resources/pdf/dorene1.pdf

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particle size, roughness, and conductivity present hazards in the use of electrical equipment (resistivity