Pressure switch

microage97
microage97 Registered Users Posts: 12 ✭
in Solar Water Pumping #1
Hello All,

I need a square D type pressure switch for a flojet 12/24 V pump. What are people using?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,716 admin
    #2
    One of the problems with switched DC power is that motors can create pretty high voltages from inductance/rotational energy. When the switch is first opened, the motor tries to draw current by generating upwards of a few hundred volts (DC brushed motor turns into a DC genset).

    Placing a flyback diode across the motor +/- connections (reverse biased during normal operation) can help save the contacts from arcing when the switch opens.

    https://en.wikipedia.org/wiki/Flyback_diode

    If nobody can help you with a a "DC" rated pressure switch, an AC switch rated for current may work OK with a flyback diode.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • microage97
    microage97 Registered Users Posts: 12 ✭
    #3
    Thanks! I think this model will work. It is rated up to .18kw / 32 v http://www.amazon.com/gp/product/B000BQSERE/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=ATVPDKIKX0DER
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 7,057 ✭✭✭✭✭✭
    #4
    You can also use the extra contact from the 240 to double your DC contact surface area. This pressure switch will probably outlast 5 of your DC pumps and the ones they come with.
    Thanks for the rain Bill !
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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