From: liz@poppyrecords.invalid.invalid   
      
   N_Cook  wrote:   
      
   > On 03/02/2025 17:45, Liz Tuddenham wrote:   
   > > N_Cook  wrote:   
   > >   
   > >> Only made a preliminary check o this 1KW pump and float switch in a   
   > >> sump, prior to dismantling ad exploring further.   
   > >> Sump full of water but no pump action. Moving the float about made no   
   > >> differece. Tapping the pump casing made the pump work until the float   
   > >> switch dropped to the cut off point.   
   > >> Refilling the sump and again no pump action until tapping the casing and   
   > >> again stopping properly. I cannot see what in the way of sticky motor   
   > >> brush or loose/corroded contact inside the motor housing could produce   
   > >> this symptom.   
   > >   
   > > You haven't said what sort of motor it is, but if it is a commutator   
   > > motor with brushgear, the fault could be worn-down brushes to the point   
   > > where one of them is almost-but-not-quite touching the commutator.   
   > > Tapping the motor gives some sort of contact and then the vibration of   
   > > the motor allows it to touch the commutator often enough to keep it   
   > > running.  This will give a fireworks display around the commutator and   
   > > will do considerable damage if it continues.   
   > >   
   > > If it is not a brush motor, a similar thing can happen if the terminals   
   > > have become loose.  The sudden shock torque as the motor starts is   
   > > enough to make contact and vibration will keep it running; then the   
   > > contact is lost again after the motor has stopped.   
   > >   
   > > The first things you need to check are what type of motor it is and   
   > > whether the supply is reaching the terminals in the connection box on   
   > > the motor casing.   
   > >   
   >   
   > The pump is a JTFS Mini Micro domestic sewage pumping station,   
   > probably JTFS190NN   
   > No type technical details found but no obvious external  starter cap   
   > outside the motor casing or casig bulge.   
      
   They are rated for AC only, so most unlikely to be a brush motor (which   
   might also be too noisy in this application).  If there is no visible   
   capacitor, it could be an induction-start motor or the capacitor is   
   hidden in the control box.   
      
   When it starts, is there s "snick!" noise as it reaches running speed?   
   That would be a centrufugal starting switch throwing out - and when the   
   motor is switched off,  as it slows down, you might hear the switch go   
   "Snick! " again as it resets.   
      
   > The other consideration is it was installed 10 years ago, tested working   
   > then, but never heard to be working since.   
      
   That absolutely rules out any sort of wear-related pronlem.  It would be   
   the sort of situation where the starting switch contacts become corroded   
   through lack of use.  A slight tap causes them to make contact and the   
   starting current (which is usually quite large) blows some of the   
   corrosion away.  After a few starts like this, you may find it appears   
   to work properly.   
      
   > It should have worked in a flood situation last year but it did not   
   > (automatically of its own accord that is) , no maintainece or testing or   
   > inspection in those 10 years by the owner or anyone else.   
      
   If mild corrosion in the starting switch is the cause of the problem,   
   testing it, say, once every couple of months should keep it healthy.  If   
   water has penetrated the casing, you will eventually have a much bigger   
   problem - you need to check for that with a 500v tester, just in case.   
      
   --   
   ~ Liz Tuddenham ~   
   (Remove the ".invalid"s and add ".co.uk" to reply)   
   www.poppyrecords.co.uk   
      
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