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IE 419 1 Work Design: Productivity and Safety Dr. Andris Freivalds Class #33.

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Presentation on theme: "IE 419 1 Work Design: Productivity and Safety Dr. Andris Freivalds Class #33."— Presentation transcript:

1 IE Work Design: Productivity and Safety Dr. Andris Freivalds Class #33

2 IE Work Design: Productivity and Safety Dr. Andris Freivalds Class #33

3 IE Electric Hazards (Ch. 21) Shock to personnel Ignition of combustible materials Overheating of equipment Inadvertent activation of equipment

4 IE Shock: Sudden stimulation of nervous system Current (ma)Physiological effect 1Noticeable 5Max harmless 10-15‘Let-go’ level 25-75Painful, paralysis Ventricular fibrillation 2500Clamps heart Macroshock = industrial, non-invasive, V = RI

5 IE Shock – Other Factors 1)Current path 2)Frequency 3)Resistance of skin Current (μa)Physiological effect 10Max allowable 50Fibrillation of heart Microshock – hospitals, invasive

6 IE Causes of Electrical Shock NFPA Statistics (Nat. Fire Protection Assoc.) Origin%Causes% Appliances52Worn equip.28 Wires, cords27Improper use14 Terminals, boxes12Accidental12 Other9Defective insulation11 Other35

7 IE Causes/Control of Electrical Shock -1 Bare conductor –Overhead high voltage –Electrical panels –Discharging capacitors Electrical insulation failures –High temperatures –Moisture –Oxidation –Radiation –Chemicals –Mechanical rubbing

8 IE Causes/Control of Electrical Shock -2 Equipment failure –3-wires –Insulation –Interlocks –Isolation –Fuses –GFCI

9 IE Causes/Control of Electrical Shock -3 Static electricity –Cotton, wool –Spray coatings –Humidification –Radioactivity Lightning –Lightning rods –Personnel

10 IE Ignition of Combustible Materials Isolation Lower levels of power Encapsulation Hermetic sealing Liquid fill Explosion proof equipment

11 IE Heating and Overloads Power = I 2 R Fuses Circuit breakers Thermal relays Inadvertent activation


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