초록

An AC driven pump and a DC driven pump are positioned in a sump and respectively energized as the liquid in the sump reaches two different levels, the DC driven pump being automatically tested for operation after every predetermined number of pumping cycles of the AC driven pump.

대표청구항 ▼

Apparatus for pumping liquid from a sump or the like to maintain the liquid surface below a predetermined level, comprising an AC operated pump positioned in said sump, a DC operated pump positioned in said sump, control means responsive to the level of said liquid in said sump for energizing said A

Apparatus for pumping liquid from a sump or the like to maintain the liquid surface below a predetermined level, comprising an AC operated pump positioned in said sump, a DC operated pump positioned in said sump, control means responsive to the level of said liquid in said sump for energizing said AC operated pump when said surface is at a first level and for energizing said DC operated pump when said AC operated pump is unable to pump water from said sump at a flow rate not less than the rate at which water is entering said sump, counter means for providing a count of the number of times said AC operated pump is energized and subsequently deenergized, and means responsive to said count for causing the energization of said DC operated pump the next time said liquid surface is at said first level after said count reaches a predetermined number, whereby the operation of said DC operated pump is intermittently tested.