Enter the net output of the shaft (watts) and the net electrical input to the motor (watts) into the calculator to determine the 3 Phase Motor Efficiency.

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## 3 Phase Motor Efficiency Formula

The following formula is used to calculate the 3 Phase Motor Efficiency.

**E3p = NO / NI *100**

- Where E3p is the 3 Phase Motor Efficiency (%)
- NO is the net output of the shaft (watts)
- NI is the net electrical input to the motor (watts)

## How to Calculate 3 Phase Motor Efficiency?

The following two example problems outline how to calculate the 3 Phase Motor Efficiency.

**Example Problem #1:**

- First, determine the net output of the shaft (watts). In this example, the net output of the shaft (watts) is given as 500.
- Next, determine the net electrical input to the motor (watts). For this problem, the net electrical input to the motor (watts) is given as 2000.
- Finally, calculate the 3 Phase Motor Efficiency using the equation above:

E3p = NO / NI *100

Inserting the values from above and solving the equation:

E3p = 500 /2000 *100 = 25 (%)

**Example Problem #2: **

Using the same process as above, first define the variables required by the formula. In this case, these values are:

net output of the shaft (watts) = 13

net electrical input to the motor (watts) = 82

Entering these values yields:

E3p = 13 / 82 *100 = 15.85 (%)