ELECTRICAL FORMULAS

Amperes, Horsepower, Kilowatts and KVA

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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