Source 1 Product Catalog 2017 Page 440 Index & Information

440 ELECTRICAL UNITS Source: United States Bureau of Standards The watt is the unit expressing electrical power as horsepower (hp) in mechanics; it is equal to the product of the volts (pressure) times amperes (rate of ow). Thus, 2 volts times 2 amperes would equal 4 watts in a direct current circuit. Electrical energy is sold at so much per watt hour or more generally at a given amount per kilowatt hour - which means 1,000 watt hours. this may represent 1 watt for 1,000 hours or 1,000 watts for one hour. 746 watts are equal to one horsepower or inversely 1 kilowatt (kw) is equal to about 1-1/2 horsepower. Horsepower represents the power required to lift a weight of 33,000 lbs. 1 foot in 1 minute or 550 lbs. 1 foot in 1 second. The ohm is the unit of electrical resistance and represents the physical property of a conductor which offers a resistance to the ow of electricity, permitting just 1 ampere to ow at 1 volt of pressure. FORMULAS - COOLING CAPACITY* Total BTUH = CFM X (THC 1 - TCH 2 ) X 4.5 TCH = Total Heat Content or Enthalpy (BTU. per lb of air) Sensible BTUH = CFM (T 1 - T 2 ) X 1.08 T = Dry Bulb Temp (Degrees Fahrenheit) Latent BTUH = CFM (W 1 - W 2 ) X .683 W = Speci c Humidity (Grains H 2 0 per lb. of air) (See Psychrometrics chart) * Based on standard air at 13.3 cubic feet per lb. ELECTRICAL UNITS CORRECTION FACTOR HEATING CORRECTION FACTOR 260 250 240 230 220 210 200 .7 .8 .9 1.0 1.1 SUPPLY VOLTAGE AT UNIT FORMULAS - HEATING CAPACITY* BTUH = CFM x 1.08 x Rise CFM = BTUH Output 1.08 x Rise Rise = BTUH Output 1.08 x CFM CFM = BTU/Hr. Input Indoor Furnace 80% 1.35 x T CFM = BTU/Hr. Input Outdoor Furnace 75% 1.44 x T CFM = KW x 3415 Electric Heat 92% 1.08 x T * Based on standard air at 13.3 cubic feet per lb. Capacity Correction Factor For correction of unit output, multiply the correction factor times the KW rating at 240 volts. TR = 3160 x KW x VC or CFM = 3160 x KW x VC CFM TR Where: TR = temp. rise, F 3160 = constant KW = KW rating above CFM = air ow at speci ed conditions VC = heating correction factor Formulas - General Subjects Area of Circle = 0.7854 (Dia.) 3 Circumference of Circle = 3.14 x Dia. Area of Sphere = 3.14 x (Dia.) 2 Volume of Sphere 0.524 x (Dia.) 3 Horsepower Conversion Chart To convert decimal horsepower to commonly available fractional horsepower motors. DECIMAL HORSEPOWER 0.010 0.014 0.017 0.020 0.025 0.033 00.40 0.050 0.067 0.083 0.100 0.125 0.167 0.250 0.333 0.500 0.750 1.000 FRACTIONAL HORSEPOWER 1/100 1/70 1/60 1/50 1/40 1/30 1/25 1/20 1/15 1/12 1/10 1/8 1/6 1/4 1/3 1/2 3/4 1

Previous Page
Next Page