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  1. #1
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    Protection relay system for pumps

    Hi.

    I'm new to the forum and my knowledge of electronics is pretty basic - not to say rusty! I'm hoping for a bit of help and inspiration.

    I have just installed a couple of pumps, one for ground water seeping in under the house and one which takes both rainwater and groundwater. In addition I have a pump drawing water from the tank these pumps empty into to and used to flush our toilets. This pump has a small pressure tank switching on when the pressure drops below a certain threshold. The other pumps turn on when the water level rises above a certain level and off when it drops again. Normally the pumps only pump for max a couple of minutes at a time.

    The other day a pipe burst but as I was home and saw it I could turn it off otherwise it would have continued pumping air until it had burned out. I realise now that I really need some kind of protection.

    I want to make a switch which cuts the power off with constant use after a certain time - variable from zero to around ten minutes, and with a manuel reset required if triggered. It would be nice with an override switch and a green light when not triggered and power on and a red light when triggered. The pumps run on 220 v mains electric. Its very difficult accessing the pumps themselves so I really need something that works on the two lead power lines. The two ground pumps share a neutral line.

    Any help would be very welcome.

    Thanks.

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  2. #2
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    Protection relay system for pumps

    Instead suggesting you any circuits, i would like to suggest you a way out for this. You may choose which one to go for.
    Or you may monitor the flow of water coming out of the outlet, and give a timed feedback to the pump so that it swicthes OFF if no water comes out within the specified time from the moment the motor is swicthed ON.
    Other way is to monitor the consumtion of the pump. While the water is bieng pumped, the current consumption will be approx the one marked on the motor / the motor rated for. When no water is pumped, the motor runs freely which drops the consumption which can be monitored and fed back to the circuit controlling the motor to swiicth OFF.
    Cheers



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  3. #3
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    Re: Protection relay system for pumps

    Quote Originally Posted by pranam77
    Instead suggesting you any circuits, i would like to suggest you a way out for this. You may choose which one to go for.
    Or you may monitor the flow of water coming out of the outlet, and give a timed feedback to the pump so that it swicthes OFF if no water comes out within the specified time from the moment the motor is swicthed ON.
    Other way is to monitor the consumtion of the pump. While the water is bieng pumped, the current consumption will be approx the one marked on the motor / the motor rated for. When no water is pumped, the motor runs freely which drops the consumption which can be monitored and fed back to the circuit controlling the motor to swiicth OFF.
    Cheers
    Thanks for your response.

    I'm not sure its easier to monitor the flow at the outlet. Its rather more difficult to get to for maintenance and I'll need some kind of mechanical sensor more prone to error. Yes I was thinking of the possibility of monitoring the current but what happens if the pump gets blocked or if water somehow runs back - say if a part in the pump breaks or it leaks?



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  4. #4
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    Protection relay system for pumps

    But still you may build a current monitor which will trrip the relay when the current varries below it abouve the set point which will serve even when the pump gets blocked...Cheers



  5. #5
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    Re: Protection relay system for pumps

    Quote Originally Posted by pranam77
    But still you may build a current monitor which will trrip the relay when the current varries below it abouve the set point which will serve even when the pump gets blocked...Cheers
    Thanks. I'll look into it.



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