Engineering Formulas
Engineering Formulas

Below is a list of helpful engineering formulas

`Ohm's Law:`
```Ohms = Volts/Amperes (R = E/I)
Amperes = Volts/Ohms (I = E/R)
Volts = Amperes x Ohms (E = IR)```

`Power-- A/C Circuits:`
```Efficiency = 746 x Output Horsepower
Input Watts

Three-Phase Kilowatts= Volts x Amperes x Power Factor x 1.732
1000

Three-Phase Volt-Amperes = Volts x Amperes x 1.732

3-Phase Amperes =            746 x Horsepower
1.732 x Volts x Efficiency x Power Factor

3-Phase Efficiency =           746 x Horsepower
Volts x Amperes x Power Factor x 1.732

Three-Phase Power Factor =        Input Watts
Volts x Amperes x 1.732

Single-Phase Kilowatts = Volts x Amperes x Power Factor
1000

Single-Phase Amperes =          746 x Horsepower
Volts x Efficiency x Power Factor

Single-Phase Efficiency =             746 x Horsepower
Volts x Amperes x Power Factor

Single-Phase Power Factor =   Input Watts
Volts x Amperes

Horsepower (3-phase) = Volts x Amperes x 1.732 x Efficiency x Power Factor
746

Horsepower (1-phase) = Volts x Amperes x Efficiency x Power Factor
746```

 `Power - D-C Circuits:` ```Watts = Volts x Amperes (W = EI) Amperes = Watts (I = W/E) Volts Horsepower = Volts x Amperes x Efficiency 746``` `Speed - A-C Machinery:` ```Synchronous RPM = Hertz x 120 Poles Percent Slip = Synchronous RPM - Full-Load RPM x 100 Synchronous RPM ``` `Motor Application:` ```Torque (lb.-ft.) = Horsepower x 5250 RPM Horsepower = Torque (lb.-ft.) x RPM 5250``` `Time for Motor to Reach Operating Speed (seconds):` ``` Seconds = WK2 x Speed Change 308 x Avg. Accelerating Torque WK2 = Inertia of Rotor + Inertia of Load (lb.-ft.2) Average Accelerating Torque = [(FLT + BDT)/2] + BDT + LRT 3 FLT = Full-Load Torque BDT = Breakdown Torque LRT = Locked Rotor Torque Load WK2 (at motor shaft) = WK2 (Load) x Load RPM2 Motor RPM2 ``` ```Shaft Stress (P.S.I.) = HP x 321,000 RPM x Shaft Diam.3```

 Centrifugal Applications: - Affinity Laws for Centrifugal Applications Flow1 = RPM1 Flow2   RPM2 Pres1 = (RPM1)2 Pres2   (RPM2)2 BHP1 = (RPM1)3 BHP2   (RPM2)3 `For Pumps:` ```BHP = GPM x FT x Specific Gravity 3960 x Efficiency of Pump BHP = GPM x PSI x Specific Gravity 1713 x Efficiency of Pump Head in Feet = 2.31 PSIG``` `For Fans and Blowers:` ```BHP = CFM x PSF 33000 x Efficiency of Fan BHP = CFM x PSW 6344 x Efficiency of Fan BHP = CFM x PSI 229 x Efficiency of Fan``` Where: BHP  = Brake Horsepower CFM  = Cubic Feet per Minute FT   = Feet GPM  = Gallons per minute PSI  = Pounds per square inch PSIG = Pounds per square inch gravity PSF  = Pounds per square foot PIW  = Inches of water gauge Specific Gravity of Water = 1.0

### INDUSTRY ABBREVIATIONS

cm = centimeter cu. = cubic ft. = foot gl. = gallon (US)
gr. = gram Imp. = Imperial in. = inch kg. = kilogram
km. = kilometer l. = liter lb. = pound m. = meter
mi. = mile oz. = ounce qt. = quart std. = standard
US = United States yd. = yard

### LENGTH MEASUREMENTS

Common Usage   Reciprocal Value
1 ft. = 12 in..   1 in. = 0.0833 ft.
1 yd. = 3 ft.   1 ft. = 0.3333 yd.
1 rod = 5.5000 yd.   1 yd. = 0.1818 rods
1 furlong = 40 rods   1 rod = 0.0250 furlongs
1 mile = 8 furlongs   1 furlong = 0.1250 mi.
1 mi. = 5,280 ft.   1 ft. = 0.000189 mi.
1 mi. = 1,760 yd.   1 yd. = 0.000568 mi.
1 fathom = 6 ft.   1 ft. = 0.1667 fathom
120 fathoms = 1 cable   1 cable = 0.00833 fathoms
1 league = 3 mi.   1 mi. = 0.3333 leagues
1 nautical mi. = 6076.11 ft.   1 ft. = 0.000165 natical mi.
1 hand = 5 in. (equestrian)   1 in. = 0.2000 hands

METRIC
1 in. = 2.54 cm.   1 cm. = 0.3937 in.
1 ft. = 30.48 cm.   1 cm. = 0.0328 ft.
1 m. = 3.2808 ft.   1 ft. = 0.3048 m.
1 m. = 39.37 in.   1 in. = 0.0254 m.
1 m. = 1.0936 yd.   1 yd. = 0.9144 m.
1 rod = 5.029 m.   1 m. = 0.1988 rod
1 km = 1000 m.   1 m. = 0.001 km.
1 km = 0.621 mi.   1 mi. = 1.6103 km.

### SQUARE MEASURES

Common Usage   Reciprocal Value
1 sq. ft. = 144 sq. in.   1 sq. in = 0.0069 sq. in.
1 sq. yd. = 9 sq. ft.   1 sq. ft. = 0.1111 sq. yd.
1 sq. rod = 30.25 sq. yd.   1 sq. yd. = 0.0331 sq. rods
1 sq. mi. = 640 acres   1 acre = 0.0016 sq. mi.

METRIC
1 sq. cm. = 0.1550 sq. in.   1 sq. in. = 6.452 sq. cm.
1 sq. ft. = 0.0929 sq. m.   1 sq. m. = 10.7643 sq. ft.
1 sq. m. = 1.196 sq. yd.   1 sq. yd. = 0.8361 sq. m.
1 hectare = 2.47 acres   1 acre = 0.4049 hectares
1 sq. km. = 0.386 sq. mi.   1 sq. mi. = 2.59 sq. km.

AWG to Metric Conversion - American Wire Gauge Conversion Chart
 AWG mm2 AWG mm2 30 0.05 8 10 28 0.08 6 16 26 0.14 4 25 24 0.25 2 35 22 0.34 1 50 21 0.38 2/00 70 20 0.5 3/00 95 18 0.75 4/00 120 18 (UL) 1 300MCM 150 17 1 350MCM 185 16 1.5 500MCM 240 14 2.5 600MCM 300 12 4 750MCM 400 10 6 1000MCM 500