Coil Saturation Current Causing Damage

Discussion in 'Homework Help' started by Progtheater, Sep 16, 2013.

  1. Progtheater

    Thread Starter New Member

    Sep 16, 2013
    4
    0
    Hi, this is my first post here, so hopefully i'm posting in the right place.

    So my question is, if a simple DC circuit with a series connected inductor and resistor needs 5A for coil saturation, the components in the circuit might overheat and get damaged if allowed to flow for a long time. Is there anyway to mitigate this risk??

    I tried to google for solutions but i'm not getting anything. I might be using the wrong keywords though, so if anyone knows the right term i should be googling or any solutions for this, please share it with me. Thank you in advance.
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,570
    2,381
    What is the nature of the coil and its purpose?
    Max.
     
  3. Progtheater

    Thread Starter New Member

    Sep 16, 2013
    4
    0
    The nature and purpose of the coil are not stated. Just need a method to keep the coil saturated at 5A while reducing the risk of damage to the resistor.
     
  4. WBahn

    Moderator

    Mar 31, 2012
    17,788
    4,807
    Pick components that are properly rated for the load they are expected to carry.
     
    Progtheater likes this.
  5. Progtheater

    Thread Starter New Member

    Sep 16, 2013
    4
    0
    WBahn: What if i am unable to select ideal components that can run on 5A for long periods of time, are there any possible circuits or components that can be added to solve this problem?

    Thanks for all the prompt replies.
     
  6. The Electrician

    AAC Fanatic!

    Oct 9, 2007
    2,285
    331
    Reduce the supply voltage powering the series resistor and inductor circuit. That way the resistor won't need to dissipate so much power.
     
    Progtheater likes this.
  7. #12

    Expert

    Nov 30, 2010
    16,347
    6,835
    I think there is something strange about protecting hypothetical parts from overheating, but that seems to be the heart of the question.

    With a voltage causing a current through a resistor and a coil, which part will get hot? Find that and you will find what you're trying to protect from heat.
     
    Progtheater likes this.
  8. Progtheater

    Thread Starter New Member

    Sep 16, 2013
    4
    0
    This topic comes from a electrical safety course i'm currently attending, explaining the strange question.

    Thanks to everyone for giving me pointers.
     
  9. strantor

    AAC Fanatic!

    Oct 3, 2010
    4,302
    1,988
    Throw it in a cooler full of dry ice.

    But seriously, this is one of the more badly written questions I've seen in a while (nothing against you, I'm sure you didn't write it). If you MUST keep 5A flowing, and 5A is enough to cause it to overheat, then the only option is active cooling. Use a heat sink mountable resistor bolted to an aluminum extrusion with a cooling fan. For the inductor, I don't know, perhaps put it in an enclosure full of mineral oil and cycle the oil through a radiator.

    Maybe the question would make more sense if I was attending the class and had the context in which it was asked.
     
  10. Brownout

    Well-Known Member

    Jan 10, 2012
    2,375
    998
    Use a timer to cut off current.
     
  11. strantor

    AAC Fanatic!

    Oct 3, 2010
    4,302
    1,988
    But then there isn't 5A flowing, so the conditions aren't met.
     
  12. Brownout

    Well-Known Member

    Jan 10, 2012
    2,375
    998
    I disagree:

    Guess it's all in how you read the question.
     
  13. t06afre

    AAC Fanatic!

    May 11, 2009
    5,939
    1,222
    I have also problem understanding the question. It is quite bad written. Maybe the tutor is looking for something like using a 100% duty cycle puls to activate the coil. Then changing to a lower duty cycle or lower input voltage for the long term operation. But as the question is written. This option are not allowed. Talk about "catch 22" question. Please post the solution given by your teacher. I am quite interested to know
     
  14. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,570
    2,381
    As most have pointed out, you have a component that requires a certain current to operate, but this current causes the component to overheat.
    Bottom line is a design flaw.
    It is like designing an Induction heater coil and not running cooling liquid through the coil, without it the coil melts!
    Max.
     
  15. WBahn

    Moderator

    Mar 31, 2012
    17,788
    4,807
    But in his next post he added, "The nature and purpose of the coil are not stated. Just need a method to keep the coil saturated at 5A while reducing the risk of damage to the resistor."

    Very poor question (though perhaps the context of the surrounding material makes it make sense).

    We need to know what the variables are that we can control in order to achieve this.
     
  16. Brownout

    Well-Known Member

    Jan 10, 2012
    2,375
    998
    The timer does keep the coil saturated, until just before it burns up. If that solution isn't adequate, then the OP can clear up the requriements.
     
Loading...