Using AC for a 220V DC solenoid

Discussion in 'General Electronics Chat' started by DeMich, Dec 4, 2013.

  1. DeMich

    Thread Starter New Member

    Dec 4, 2013
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    Hey guys,


    I need to use this 220Vdc solenoid. (0.68A Pull type solenoid electromagnet)


    I would like to use 220Vac. Is there any way I can try this?


    What I've found in an older thread: possible when using full wave bridge rectifier & a capacitor.
    But the output voltage is 1.4xVin... . So if I want to try this, I'll have to create a Vin of 157.
    Or I leave my Vin at 220Vac & my Vout becomes 308Vdc. But I don't think thats wise for the solenoid... Or I'm a wrong...




    I could use some prof help ;)




    thx
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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    You do not need the capacitor, the pull in voltage will then be correct.
    If control circuit has electronics, place a reverse connected rectifier diode across the coil.
    Max,
     
  3. TheComet

    Member

    Mar 11, 2013
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    You'll still have 308V spikes at 100Hz.
     
  4. DeMich

    Thread Starter New Member

    Dec 4, 2013
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    It supposed to be controlled by a 220vac relay.

    A reverse connected rectifier diode, don't really see what you mean.

    thx
     
  5. MaxHeadRoom

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    The non-cap method has been used for many decades on DC brakes, solenoids and other DC inductive devices, it pays to place the reverse diode anyway, as this also helps to retain the armature during the brief transition to zero.
    Max.
     
    DeMich likes this.
  6. crutschow

    Expert

    Mar 14, 2008
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    The peak (not spikes) voltage of 220VAC is indeed 308V, but the RMS value of the full-wave rectified unfiltered voltage is 220V which is fine for a 220VDC solenoid.
     
  7. DeMich

    Thread Starter New Member

    Dec 4, 2013
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    Hey, thanks for the advice. But could you explain the reverse rectifier diode a little more. Don't understand how to do this.
     
  8. inwo

    Well-Known Member

    Nov 7, 2013
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    Do not want capacitor, voltage will already be marginally high in my experience.

    I believe this is what was meant.
     
  9. inwo

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    If solenoid will be energized for long periods, I would check current or temperature to be sure it's not overheating.
     
  10. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    D1-D4 are a rectifier bridge. D5 is the 'freewheel' diode for spike suppression.
     
  11. MaxHeadRoom

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    Post#10 shows how it is connected, the down side in some circuits that require H.S. switching is the delay it causes on drop out, depending on the energy stored, for the majority of general purpose applications it is not noticeable.
    When the relay/solenoid/coil turns off there is a back EMF generated from the collapsing field, which in many cases can be up to 10-100 times higher than the applied voltage.
    The rectifier provides a recycle path for the collapsing field and effectively quenches it.
    Max.
     
  12. crutschow

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    Note that the bridge rectifier will also provide a path for the collapsing field current so the dropout would still be delayed, even with no added diode.
     
  13. MaxHeadRoom

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    How would the path be completed with the load end open circuit?
    Max.
     
  14. inwo

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    Both right!

    Depends on switching the ac side or the dc side.
     
  15. MaxHeadRoom

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    In a common usage, one end of the inductor would be switched, either by relay or S.S. device.
    There are often (steering) bridges placed within a DC solenoid even where it is switched with a DC source, this is done in order to prevent wrong polarity when connected and where a reverse diode is wired internally.
    Max.
     
  16. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    I would do it like this: I recently needed to drive a 100Vdc water solenoid from 120Vac, and used something similar.

    A DC solenoid is likely to buzz if driven with half or full-wave rectified DC, so I am adding just enough filtering so that the current through the solenoid is more-or-less DC. To come up with the final circuit, you should measure the DC resistance of the solenoid coil, and then some adjustment of R1 or C1 might be necessary.

    Note in the example below, I picked R1 and C1 such that the RMS value of voltage across the coil is close to its DC rating. If your coil resistance is more or less than my assumed 2000Ω, then we can adjust as needed.

    With the capacitor across the coil, a snubber diode is not needed.
     
  17. MaxHeadRoom

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    I have never seen this in all the applications I have used using full wave, even with some large DC brakes and clutches.
    Although the voltage transitions to zero, the current does not (scope it), and especially if using the reverse diode, in fact in large devices where the energy stored is large, you can actually see the delay when you turn the device off.
    On 60Hz, the 8ms of voltage dip should not be enough to cause buzz.
    I would not recommend 1/2 wave for unfiltered supply.
    Max.
     
  18. inwo

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    I've tried half wave with enough capacitance to get just the right power level.

    Must select capacitors that will take the high ripple and abuse.
    I like the type used in run capacitors from ceiling fans.

    In the end full wave seems the best.
     
  19. inwo

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    This is a clutch driver circuit I'm getting some pcb's for.
     
  20. MaxHeadRoom

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    I am wondering why anyone would use 1/2 wave when considering the low cost of rectifiers?
    Max.
     
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