| 摘要 |
PROBLEM TO BE SOLVED: To provide a pump installation automatically operating alternately two or more submerged pumps by an inexpensive and simple structure with the number of float switches minimized. SOLUTION: The first submerged pump 1 has the first float switch 10 for detecting a first operation starting water level L<SB>S1</SB>and a first operation stopping water level L<SB>E1</SB>, and is formed to start operation when detecting the first operation starting water level L<SB>S1</SB>and to stop operation when detecting the first operation stopping water level L<SB>E1</SB>. The second submerged pump 2 has the second float switch 20 for detecting a second operation starting water level L<SB>S2</SB>and a second operation stopping water level L<SB>E2</SB>, and the third float switch 30 for detecting an abnormal water level L<SB>A</SB>, and is formed to start operation by a rate of one per predetermined frequencies when detecting the second operation starting water level L<SB>S2</SB>, stop operation when detecting the second operation stopping water level L<SB>E2</SB>, and start operation when detecting the abnormal water level L<SB>A</SB>. COPYRIGHT: (C)2007,JPO&INPIT
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