What is the motor full-load current for a motor with a nameplate rating of 50hp, 460V, 3Ø?

• A. 50A
• B. 65A
• C. 70A
• D. 75A

Answer: (B)

To determine the motor full-load current for a three-phase motor with a nameplate rating of 50 horsepower (hp) and 460 volts (V), you can use the formula that relates horsepower to electrical current. The formula for three-phase motors is:

[

I = \frac{P \times 746}{\sqrt{3} \times V \times PF}

]

Where:

• (I) is the current in amperes (A),

• (P) is the horsepower (in this case, 50 hp),

• 746 is the conversion factor from horsepower to watts,

• (V) is the voltage (460 V),

• (PF) is the power factor (commonly taken as 1 for calculations unless otherwise specified).

Assuming a power factor of 1 (for simplicity), the calculation becomes:

[

I = \frac{50 \times 746}{\sqrt{3} \times 460}

]

Calculating this step-by-step:

1. Convert horsepower to watts:

( 50 \times 746 = 37300 ) watts.

2. Calculate the factor of (\sqrt{3}):

( \sqrt{3} \approx