Question

The Field And Armature Resistances Of A Series 320 V Dc Motor Are Rse=0.35Ω, And Ra=0.25Ω. The Motor Draws 50 A From Supply, While Running At 800rpm. If The Constant Losses Are 500 W, Calculate: Draw And Label A Complete Circuit Diagram →

The Efficiency Of The Motor At This Load %Η=

Answer 1

To calculate the efficiency of the motor at this load, use the formula %Η = (Power output / Power input) x 100%. First, calculate the voltage across the motor, then calculate the power output and power input. Finally, use the efficiency formula to find the percentage.

Step-by-step explanation:

The efficiency of a motor can be calculated using the formula:

%Η = (Power output / Power input) x 100%

To calculate the power output, we can use the formula:

Power output = (Voltage across the motor - Back emf) x Current

First, we need to calculate the voltage across the motor:

Voltage across the motor = Voltage supply - (Field resistance x Current)

Substituting the given values:

Voltage across the motor = 320V - (0.35Ω x 50A)

Next, we can calculate the power output:

Power output = (320V - (0.35Ω x 50A) - (0.25Ω x 50A)) x 50A

To calculate the power input, we can use the formula:

Power input = Voltage supply x Current

Substituting the given values:

Power input = 320V x 50A

Finally, we can calculate the efficiency using the formulas above:

%Η = (Power output / Power input) x 100%

Remember to convert the answer to a percentage to get the efficiency of the motor at this load.