20A

YOUR ANSWER: 77.7 percent

Correct. We had an input of 960 watts and an output of one horsepower. We were told

that one horsepower is equal to 746 watts; our problem looks like this:

Efficiency = output x 100 =746

input

960 x 100 = .777 x 100 = 77.7 percent.

The balance of power, 22.3 percent, is lost as heat or friction.

Heat and Friction Losses

22.3 percent of power

Delivered

Power

746 w.

77.7

percent

(output)

In the figure above are pictured the power and the power losses. If you follow the

arrows through this picture, you will find the input power is electrical power. It splits up in the

motor, going in two directions. The losses in the form of heat are radiated upward, and the

output in the form of mechanical power is delivered to the shaft.

Now consider this problem. We have a 5-horsepower motor that draws 20 amperes

from a 200-volt circuit; what is the efficiency of this motor?

93.25 percent.

frame 22A

107.23 percent

frame 24A

1-21

IT0348

Integrated Publishing, Inc.
6230 Stone Rd, Unit Q
Port Richey, FL 34668
Phone For Parts Inquiries: (727) 493-0744 Google + |