DC Solinoid

It works the same way any electromagnetic device does. Applies current to the coil and attracts the iron/steel rod, and upon stopping current the rod is release to the normal position. AC solenoids are more powerful than DC solenoids, therefore DC solenoids have less risk of malfunctioning (remain stuck in the open position) than AC due to limited inrush.

Hey AW, your said "AC solenoids are more powerful than DC solenoids, therefore DC solenoids have less risk of malfunctioning ...". My experience tells me it is not that DC solenoids are less powerful than AC that results in less risk of malfunction.

1st. most malfunctions are mechanical, so a more powerful (not less powerful) coil would be more likely to overcome mechanical resistance like solenoid getting gummed up. But more accurately, AC solenoids depend on spring return (mechanical) so risk of failure increased that much more.

The least risk of failure solenoid design, given the above facts, would be one that is DC using reverse polarity to return solenoid back to home position instead of spring return. Then you could apply more force (current) for return cycle than size limitations would allow for a spring return type. There by reducing risk of failure by it's ability to overcome more mechanical resistance than a spring could.

Of course if size was not a limitation, you could just use a BAS (Big Ass Spring).

Note: if you are referring to DC Valve, it is a whole different story, as DC is used to control variable and partial opening and closing of valve and acuracy of that function.

Hope this helps clarify.

My bad, after rereading my comment I can see how my "therefore" messed up my points. You're absolutely correct, AC are not more prone to failure because they're more powerful (like my statement can make any sense). What I was trying to say was in real practice AC solenoids are more prone to failure where AC solenoids are applicable, compared to DC where applicable in their domain.

Bin95: how do you apply more force (current) for return cycle raise the voltage?, capacitor discharge? Are you talking a gate or butterfly or ball valve?

DC solenoids are reversible. Just reverse the polarity.

I already indicated that DC solenoids are reversible when I mentioned you could reduce risk of mechanical failure by "DC using reverse polarity to return solenoid back to home position instead of spring return".

Sorry, you're right.

Bin95; I feel your incorrect when you state that reversing the D.C.would push the soft iron plunger out of the solenoid. I don't think so!! A D.C. relay will pull in/close it don't care where +plus or - neg voltage is applied to which terminal. Perry

Very well, thank you.