Pumping Calculations - Basic Mathematics for Water and Wastewater Operators - page 215

Solution:

Volt s × Amperes × Power factor × 1.732 = 440 volts × 42 amperes × 0.9 × 1.732

= 28,806.62 watts

■ Example 14.56
Problem: How many kilowatts of power does a three-phase motor use if it pulls 23
amperes at 440 volts and has a power factor of 0.9?

Solution:

Volts × AmperesPower factor × × 1.732 440 volts × amperes

1000 watt

23 × 09 1 732 . × .

=

1000 watts/ kW s/kW

= 15 78 . kW

■ Example 14.57
Problem: What is the power factor on a system that uses 3853 watts and pulls 10
amperes at 440 volts?

Solution:

Watts 3853

40 volts

watts

Powerfactor = = = 088 .

VoltsAmperes × 4 × 10 amperes

■ Example 14.58
Problem: What is the power factor on a system that uses 3888 watts and pulls 122
amperes at 440 volts?

Solution:

Watts 3888

40 volts

watts

Powerfactor = = = 074 .

VoltsAmperes × 4 × 12 amperes

■ Example 14.59
Problem: During a 60-min pumping test, 9250 gal are pumped into a tank that has a
length of 12 ft, width of 8 ft, and depth of 6 ft. The tank was empty before the pump-
ing test was started. What is the gpm pumping rate?

Solution:

9250 gal ÷ 60 min = 154.2 gpm