What is the approximate decrease in rated wattage if a 240V unit is connected to a 208V power supply?

What is the approximate decrease in rated wattage if a 240V unit is connected to a 208V power supply?

• A. 10%
• B. 20%
• C. 25%
• D. 30%

Answer: (C)

When a 240V unit is connected to a 208V power supply, the voltage decrease affects the wattage output of the unit. To understand the relationship between voltage and wattage, it's essential to remember that power (in watts) is proportional to the square of the voltage (V²) in resistive loads. In this scenario, you can calculate the percentage decrease in wattage by comparing the square of the supplied voltage (208V) to the square of the rated voltage (240V). The formula for power based on voltage is: Power = Voltage² / Resistance (which remains constant). Calculating the power at each voltage gives: - At 240V: \( P_{240} \) = 240² = 57600 - At 208V: \( P_{208} \) = 208² = 43264 Now, to find the decrease: 1. Determine the difference in power: \( 57600 - 43264 = 14336 \). 2. Calculate the percentage decrease: \( (14336 / 57600) \times 100 \approx 24.87\% \), which can be rounded to approximately 25%. Thus, the decrease in rated watt

When a 240V unit is connected to a 208V power supply, the voltage decrease affects the wattage output of the unit. To understand the relationship between voltage and wattage, it's essential to remember that power (in watts) is proportional to the square of the voltage (V²) in resistive loads.

In this scenario, you can calculate the percentage decrease in wattage by comparing the square of the supplied voltage (208V) to the square of the rated voltage (240V). The formula for power based on voltage is:

Power = Voltage² / Resistance (which remains constant).

Calculating the power at each voltage gives:

• At 240V: ( P_{240} ) = 240² = 57600

• At 208V: ( P_{208} ) = 208² = 43264

Now, to find the decrease:

1. Determine the difference in power: ( 57600 - 43264 = 14336 ).

2. Calculate the percentage decrease: ( (14336 / 57600) \times 100 \approx 24.87% ), which can be rounded to approximately 25%.

Thus, the decrease in rated watt