### AC Motor Formula

```AC Motor Formula
To Find Amperes when HP is known:
Single Phase
I=
746∗ HP
E ∗ Eff ∗ PF
Two Phase - *(4 - wire)
I=
746∗ HP
2∗ E ∗ Eff ∗ PF
Three Phase
I=
746∗ HP
173
. ∗ E ∗ Eff ∗ PF
To find Amperes when KW is known:
Single Phase
I=
1000∗ KW
E ∗ PF
Two Phase - *(4 - wire)
1000∗ KW
2∗ E ∗ PF
I=
Three Phase
I=
1000∗ KW
173
. ∗ E ∗ PF
To find Amperes when KVA is known:
Single Phase
I=
1000∗ KVA
E
Two Phase - *(4 - wire)
I=
Three Phase
1000∗ KVA
2∗ E
I=
1000∗ KVA
173
. ∗E
To find Kilowatts Input:
Single Phase
KW =
E ∗ I ∗ PF
1000
Two Phase - *(4 - wire)
KW =
2∗ E ∗ I ∗ PF
1000
Three Phase
KW =
173
. ∗ E ∗ I ∗ PF
1000
To find Kilovolt Amperes:
Single Phase
KVA =
E∗ I
1000
Two Phase - *(4 - wire)
KVA =
2∗ E ∗ I
1000
Three Phase
KVA =
173
. ∗ E∗ I
1000
To find Horsepower Output:
Single Phase
HP =
E ∗ I ∗ Eff ∗ PF
746
Two Phase - *(4 - wire)
HP =
2∗ E ∗ I ∗ Eff ∗ PF
746
Three Phase
HP =
173
. ∗ E ∗ I ∗ Eff ∗ PF
746
* For two phase three wire balanced circuits, the Amperes in common cunductor = 1.41 times that in either of the two.
Synchronous Speed:
ns =
120∗ f
P
Frequency:
Number of poles:
P∗ ns
f =
120
P=
120∗ f
ns
n=
5250 HP
T
Relation between horsepower, torque and speed:
HP =
T∗ n
5250
T=
5250 HP
n
Motor Slip:
%Slip =
ns − n
∗100
ns
```