Electrical Electronics Engineering Important Formulas List

Here I would like to discuss some of the important electrical and electronics engineering formulas. All these formulas are useful for basic calculation in Electrical Engineering and Electronics Engineering including Voltage, Ampere, Power, efficiency, power factor and much more. I hope it can make your basic understanding about electrical and electronics calculation is clear and I just need your simple thanks below in comment section.

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Glossary of Electrical


I = Amperes
E = Volts
kW = Kilowatts
kVA = Kilo volt-Amperes
HP = Horsepower
% eff. = Percent Efficiency
pf = Power Factor


Single-Phase Formulas


To Find;

1. Amperes when kVA is known –>   I = kVA x 1000 / E
2. Amperes when horsepower is known –>  ( HP x 746) / ( E  x  % eff.  x pf )
3. Amperes when kilowatts are known –>  ( kW x 1000 ) / ( E x pf )
4. Kilowatts  –>  ( I x E x pf ) /1000
5. Kilovolt-Amperes  –>  ( I x E ) / 1000
6. Horsepower  –>  ( I x E x % eff. x pf  ) / 746
7. Watts   –>  E x I x pf
8. Energy Efficiency  –>  Load Horsepower x 746 / Load Input kVA x 1000
9. Power Factor  @ cos θ –>  Power Consumed /Apparent Power ( W / VA ) @ ( kW / kVA)


Two-Phase Formulas

To Find;

Amperes when kVA is known –>   I = ( kVA x 1000 )  / ( E x 2 )
Amperes when horsepower is known –>  ( HP x 746) / ( E  x  2  x % eff.  x pf )
Amperes when kilowatts are known –>  ( kW x 1000 ) / ( E x 2 x pf )
Kilowatts  –>  ( I x E x 2 x pf ) /1000
Kilovolt-Amperes  –>  ( I x E x 2 ) / 1000
Horsepower  –>  ( I x E x 2 x % eff. x pf  ) / 746
Watts   –>  E x I x 2 x pf
Energy Efficiency  –>  Load Horsepower x 746 / Load Input kVA x 1000
Power Factor  @ cos θ –>  Power Consumed /Apparent Power ( W / VA ) @ ( kW / kVA)


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Three-Phase Formulas

To Find;

1. Amperes when kVA is known –>   I = ( kVA x 1000 )  / ( E x 1.73 )
2. Amperes when horsepower is known –>  ( HP x 746) / ( E  x  1.73  x % eff.  x pf )
3. Amperes when kilowatts are known –>  ( kW x 1000 ) / ( E x 1.73 x pf )
4. Kilowatts  –>  ( I x E x 1.73 x pf ) /1000
5. Kilovolt-Amperes  –>  ( I x E x 1.73 ) / 1000
6. Horsepower  –>  ( I x E x 1.73 x % eff. x pf  ) / 746
7. Watts   –>  E x I x 1.73 x pf
8. Energy Efficiency  –>  Load Horsepower x 746 / Load Input kVA x 1000
9. Power Factor  @ cos θ –>  Power Consumed /Apparent Power ( W / VA ) @ ( kW / kVA)


Others Electrical/Electronics Engineering Formulas

1. kW = hp x .746
2. Torque in lb-ft = hp x 5250 / rpm
3. Motor synchronous speed in rpm = 120 x Hz / number of poles
4. Three-phase full-load amp= hp x .746 / 1.73 x kV x effi ciency x power factor
5. Rated motor kVA = hp (.746) / efficiency x power factor
6. kW loss = hp (.746) (1.0 – effi ciency) / efficiency
7. kVA in-rush = percent in-rush x rated kVA
8. Approximate voltage drop (%) = motor kVA in-rush x transformer impedance / transformer kVA
9. Stored kinetic energy in kW-sec = 2.31 x (total Wk2) x rpm2 x 107
10. Inertia constant (H) in seconds = stored kinetic energy in kW-seconds / hp (.746)
11. Conversion factors: CV = (metric hp) = 735.5 watts = 75 kg-m/sec Wk2 (lb-ft) = 5.93 x GD2 (kg-m2)
12. Ventilating-air requirements: 100-125 cfm of 400C air at 1/2-in. water pressure for each kW of loss
13. Degrees C = (Degrees F-32) x 5/9
14. Degrees F = [(Degrees C) x 9/5 ] + 32


I hope it will be beneficial for someone. To learn more, you can download free books about Power factor, high voltage, power system and automation (All about Electrical and Electronics engineering) please visit http://engineermohsinali.blogspot.com

Read Engineering Material Free Download
Read Twelve free Intelligence books you can download
Also Electrical Automation Books free Download
Read Important Software, Every Student must have installed

Electrical Electronics Engineering Important Formulas List Electrical Electronics Engineering Important Formulas List Reviewed by Unknown on September 01, 2017 Rating: 5

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