Monday, 19 October 2015

resistance - Ohm's law doesn't seem to be working for this electric motor


I'm a beginner in this field so please forgive me if I'm confusing with my question.


There is a component that I can't understand with Ohm's law which is a washing machine drain pump. Washing machine drain pumps from most manufacturers have similar specifications. Their winding resistance is usually between 10-20 Ω and it operates under 120 VAC.


From drain pump troubleshooting



Drain pump resistance


Drain pump specification


However the specifications written on the label are quite different. 120 VAC, 1.1 A, and 80 W.


Drain pump current draw


The actual current draw, 0.9 A, is close to the specification value which is 1.1 A.


I really don't understand that according to Ohm's law the resistance value calculated per the specification should be (R = U/I) 133.33 Ω where U is 120 V and I is 1.1 A.


But why is the winding giving me 14.8 Ω?


Shouldn't it draw 8.11 A as I = U / R = 120 V / 14.8 Ω = 8.11 A?




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