| CPC F04D 15/0088 (2013.01) [G01M 3/16 (2013.01)] | 9 Claims |

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1. A pump comprising:
a motor housing accommodating a motor configured to drive an impeller to discharge fluid;
a pump cap, located above the motor housing, accommodating a controller configured to drive the motor; and
a sensor box, provided on a side of the pump, accommodating a capacitive sensor;
wherein the controller is configured to (i) drive the motor after determining that a value detected by the capacitive sensor indicates that fluid is present around the pump, wherein determining that the value detected by the capacitive sensor indicates that the fluid is present around the pump is determined based on a difference between a first value and a second value, wherein the first value is detected by the capacitive sensor, and the second value is detected by the capacitive sensor after detecting the first value, and (ii) overwrite the first value with a third value after detecting that the third value indicates that the fluid is less likely to be present around the pump than the first value does, and the third value is detected by the capacitive sensor after detecting the second value.
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