Article View: sci.electronics
Article #7294Re: Ac motor control question
From: John Whitmore
Date: Sat, 15 Sep 1990 04:23
Date: Sat, 15 Sep 1990 04:23
26 lines
1817 bytes
1817 bytes
In article <90256.174441ESV@psuvm.psu.edu> ESV@psuvm.psu.edu (ANDREW COLL esv@psuvm.psu.edu) writes: >Greetings everyone... > >I just moved into a new house and had to replace a broken pump. >I'm having a small problem controlling the motor. The pump >is actually a wastewater pump for a basement sink ... >The pump sucks all of the water out of the drain line, causing the float >switch to turn off again. About a half a second later, enough water >has flowed into the pipe again to turn the pump back on. So now, the >pump is oscillating between on and off, about fifteen times a minute. One way to approach the problem is to use a smaller pump; the 'all done' event will no longer occur so soon (but if the sink overflows, you're sunk :-) ). A better solution would be to put a standpipe on the drain line with a flapper valve and a slow leak; if the water rises, it pushes past the flapper and raises the float switch (installed, of course, in this pipe). Then when the pump turns on and the water falls, the flapper valve closes. Only much later, as the leak in the flapper drains the standpipe, the switch will turn off. My preference would be to homebrew the valve, but any commercial 'check valve' can be modified (drill a hole in the flapper) for this use. The diameter of the standpipe and the size of the hole in the flapper will determine the time delay. John Whitmore
Technical Details
Message-ID:
<7612@milton.u.washington.edu>Path:
arc1-ca.pugleaf.net!utzoo!attcan!uunet!know!zaphod.mps.ohio-state.edu!rpi!dali.cs.montana.edu!milton!whitReferences:
<90256.174441ESV@psuvm.psu.edu>Show Full Headers
Complete Article Headers
Path: arc1-ca.pugleaf.net!utzoo!attcan!uunet!know!zaphod.mps.ohio-state.edu!rpi!dali.cs.montana.edu!milton!whit From: whit@milton.u.washington.edu (John Whitmore) Newsgroups: sci.electronics Subject: Re: Ac motor control question Message-ID: <7612@milton.u.washington.edu> Date: 15 Sep 90 04:23:37 GMT References: <90256.174441ESV@psuvm.psu.edu> Organization: University of Washington, Seattle Lines: 26