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Electrical Formulas for calculating Amperes, Horsepower, Kilowatts and KVA
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| E = Voltage / I = Amps/ PF = Power Factor / EFF = Efficiency / HP = Horsepower |
To Find |
Direct Current |
Alternating
Current |
| Single
Phase |
Two-Phase*
Four-Wire |
Three
Phase |
Amperes when Horsepower is known |
HP x 746
---------------
E x EFF |
HP x 746
----------------
E x EFF x PF x 2 |
HP x 746
---------------------------
2 x E x EFF x PF |
HP x 746
------------------
E x EFF x PF x 1.73 |
| Amperes
when Kilowatts are known |
KW x 1000
-----------------
E |
KW x 1000
---------------------
E x PF |
KW x 1000
-------------------
2 x E x PF
|
KW x 1000
------------------
E x PF x 1.73 |
| Amperes
when "KVA" is known |
|
KVA x 1000
-------------------
E |
KVA
x 1000
---------------------
2 x E |
KVA x 1000
----------------------
E x 1.73 |
| Kilowatts |
E x I
--------------
1000 |
E x I x PF
----------------
1000 |
I
x E x 2 x PF
--------------------------
1000 |
E x I x 1.73 x PF
-------------------
1000 |
| Kilovolt-Amperes
"KVA"- |
|
I
x E
-------------
1000 |
I
x E x 2
------------------------
1000 |
E x I x 1.73
--------------------
1000 |
| -Horsepower (Output) |
E x I x EFF
-----------
746 |
E x I x EFF x PF
----------------
746 |
I
x E x 2 x EFF x PF
-----------------------------
746 |
E x I x EFF x PF x 1.73
---------------------------------
746 |
Note: Direct current formulas do not use (PF, 2, or 1.73)
Single phase formulas do not use (2 or 1.73)
Two phase-four wire formulas do not use (1.73)
Three phase formulas do not use (2)
* For three-wire, two phase circuits the current in the common
conductor is 1.41 times that in either of the other two conductors.
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