ELECTRICAL FORMULAS FOR CALCULATING AMPERES, HORSEPOWER, KILOWATTS, AND KVA
|
E = Voltage / I = Amps/ PF = Power Factor / EFF = Efficiency / HP = Horsepower
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To Find
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Direct Current
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Alternating Current
|
|
Single Phase
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Two-Phase* Four-Wire
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Three Phase
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Amperes when Horsepower is known
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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
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HP x 746
------------------
E x EFF x PF x 1.73
|
|
Amperes when Kilowatts are known
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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"-
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|
I x E
-------------
1000
|
I x E x 2
------------------------
1000
|
E x I x 1.73
--------------------
1000
|
|
-Horsepower (Output)
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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.