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What kind of relay is this?

Discussion in 'General Electronics Discussion' started by Davewalker5, Sep 27, 2014.

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  1. Davewalker5

    Davewalker5

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    Sep 20, 2014
    What kind of relay type is this?

    What tool would you guys use to get them out of the sockets

    When I used pilers, it squeezed the chassis of the relay and smashed it

    There is too many components around the relays to get a flat head screw driver underneath it, it lift it out
     

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  2. Davewalker5

    Davewalker5

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    Sep 20, 2014
    How do these relay suppressor network circuits work? what do they do to the relay?
     

    Attached Files:

  3. Arouse1973

    Arouse1973 Adam

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    Looks like a double pole single throw type. Two seperate contacts with two common Inputs.
    Adam
     
  4. Davewalker5

    Davewalker5

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    Sep 20, 2014
    I mean what type or kind of package? it's a type of relay

    I'm not worried about if it's a single pole or double throw
     
  5. Arouse1973

    Arouse1973 Adam

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    Dec 18, 2013
    They dont do anything to the relay, they absorb the flyback energy from the coil when the relay is switched off.
    Adam
     
  6. Arouse1973

    Arouse1973 Adam

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    Dec 18, 2013
    I dont know I dont think relays have generic footprints like other component.
    Adam
     
  7. Davewalker5

    Davewalker5

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    Sep 20, 2014
    They dont do anything to the relay, they absorb the flyback energy from the coil when the relay is switched off.

    Yes i know that is doesn't do anything to the relay

    Why are each relay suppressor network circuits different, how do they absorb the flyback energy from the coil?

    why didn't they just use one instead of using 3 different types which do what differently?

    When the relay closes or shuts off , it creates a undershoot voltage or spike

    Each Relay suppressor has a RC network configuration to time delay or to filter out the undershoot voltage spike? but why the different RC network configurations?
     
  8. Arouse1973

    Arouse1973 Adam

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    Is this a wind up? You asked what do they do to the relay?
     
  9. Davewalker5

    Davewalker5

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    Sep 20, 2014
    Mostly when I see relay, i have only seen a Diode in parallel with the relay coil. The diode clamps the flywheel voltage. So the Diode drains and sinks the coils voltage to ground.

    I don't see resistors and capacitors in different configurations like this with a relay coil. They call these networks relay suppressor network circuits

    I'm not sure what the resistors or capacitors do to the relay coil

    Do you?

    Take a look at the 3 different types of how the resistors and caps are configured to do what to the relay coil?
     

    Attached Files:

  10. Arouse1973

    Arouse1973 Adam

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    Dec 18, 2013
    The first one, cap across diode limits any flyback from the diodes inductance. The second one cap and resistor is a soft suppression, this stores the flyback energy in the capacitor rather than dumping large current into the supply. This could be used for very large coils which would make the diode option exspensive. The last one I have not seen but looking at it l would think the diode across the resistor limits the power disapated in the resistor, but that just my thoughts.
    Adam
     
  11. Davewalker5

    Davewalker5

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    Sep 20, 2014
    Williamson is not me arouse1973 , i don't know who that is

    So the cap across a diode increases or decreases the diodes inductance?

    what does the diodes inductance do to the flyback? or relay coil?

    What makes a hard suppression network? and what makes a soft suppression?

    I'm new to suppression networks, how do u know about them?

    Why would they want to store the flyback energy?

    Why not just use a diode in parallel? to sink and drain off the flyback current and voltage
     
  12. Arouse1973

    Arouse1973 Adam

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    Dec 18, 2013
    A diode clamp is very aggresive, it pushes the same current that is in the coil into the supply. This might not be allowed so caps are used to store the energy which is the slowly used by the coil until the energy is gone.
    Adam
     
  13. Davewalker5

    Davewalker5

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    Sep 20, 2014
    So you're saying that the diode sinks and drains off into the supply very fast

    The cap stores the energy and sinks and drains off the flyback energy slowly back into the supply

    Does the capacitor and resistor limit the "undershoot voltage"? or just the diode clamps the undershoot voltage?

    Because if the flyback voltage is to large what will happen? it will damage components because it's a negative voltage spike

    Semi conductors don't like a negative voltage because it breaks down the reverse biasing junctions
     
  14. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    These are all methods of reducing the voltage spike which occurs when current through the coil is interrupted.

    Those using diodes are for DC circuits.

    Those comprising only of resistors and capacitors can also be used for AC driven coils.

    A diode on its own allows the current to continue to flow around the circuit consisting of the coil and the diode until the resistance of the coil and the voltage drop of the diode cause it to fall to zero. This can make the relay slow to open, which can also cause issues with arcing contacts (because as well as a time delay, the contacts themselves open more slowly).

    There are variations with zener diodes added which increase the loss in the circuit, resulting in much faster decay of the voltage. However these will allow the reverse voltage across the relay coil to rise by the zener voltage, so the switching circuit needs to be able to handle Vcc + Vz.

    The variations with capacitors and resistors rely on the energy from the coil being transferred to the capacitor and dissipated in the resistor. This circuit will ring, but with luck (actually with good design) the voltage will rapidly fall below that required to hold the relay closed and subsequent rings will not be energetic enough to close (or keep closed) the relay.
     
  15. Davewalker5

    Davewalker5

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    Sep 20, 2014
    So it's an AC voltage that is charging or energizing the relay coil?

    The Relay coil itself has to be an AC relay coil?

    I didn't know where was DC relay coils and AC relay coils

    What you mean by how it can handle the VCC + Vz?

    The relay coil rises by the zener voltage? how can a zener diode rises the relays coil

    The zener diode just "clamps" the relays coil reverse voltage
    and then the zener diode sinks the relays coils reverse voltage and decays to zero
     
  16. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Firstly google flyback diode and make sure you understand it.

    Then consider if you place a zener diode in series with the flyback diode so that the zener breaks down when the flyback diode is forward biased. (It's like the diode has a very high forward voltage)
     
  17. Davewalker5

    Davewalker5

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    Sep 20, 2014
    Yes I have seen a zener diode in series, it's to protecting and stopping a negative voltage from the relay coil from entering into the circuit
     
  18. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    1. Do you understand what a flyback diode does?
    2. Do you understand that the voltage spike does not reverse or reduce the voltage seen by the switching device, but increases it?
     
  19. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Look at this.

    It shows a transistor turning a relay on and off.

    There is a switch in series with the diode. Click the switch to open or close it.

    There is a graph of voltage and current shown along the bottom. This is at the collector of the transistor.

    Note that when the switch is open, the peak voltage (shown in the upper left corner of the graph) is several thousand volts, When you close the switch it falls to 5.65V.

    The battery voltage is 5V. Without the diode, as the transistor switches off, the voltage at the collector rises. Of course, in reality it would only rise to the point at which the transistor breaks down. With the diode, the increase in voltage is limited to the forward voltage drop of the diode (0.65V).

    Once you understand this, I will add a zener diode in series with that diode to show you the effect it has.
     
  20. Davewalker5

    Davewalker5

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    Sep 20, 2014
    Right the diode Clamps/limits the relays coils voltage when the switch is turned off
     
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