electronic circuit protection

Discussion in 'General Electronics Chat' started by yassser, Aug 9, 2011.

  1. yassser

    Thread Starter Member

    Jul 25, 2011
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    0
    Hello ,

    I'm making a circuit to drive a 160V , 15A DC motor .

    how can I protect the elements of the circuit from over current or abusive usage , can fuses or circuit breakers work in protecting electronic elements from over current or would it be too slow for electronics .

    also what is the difference between a normal circuit breaker and a motor overload protection , why is the motor overload protection much more expensive.

    also , Is there something specific for DC .

    If there is a certain book or reference related to this , please , tell me about it .
     
  2. praondevou

    AAC Fanatic!

    Jul 9, 2011
    2,936
    488
    Hi, you are back! Did the MOSFET burn again???

    What do you want to protect? MOSFET or MOTOR?

    MOSFET:
    Overvoltage: put a snubber on it, for example an RCD clamp
    Overcurrent: best is to use an electronic overcurrent protection like the pulse by pulse limitation used in PWM current mode controllers

    Fuses most likely and definitely circuit breakers are too slow to protect a MOSFET from overcurrent.

    A fuse will however will provide some protection if you overload the motor for example.
     
  3. yassser

    Thread Starter Member

    Jul 25, 2011
    91
    0
    :] , No it didn't , I want to make sure it will not .
     
  4. yassser

    Thread Starter Member

    Jul 25, 2011
    91
    0
    I also see some boards with an earthing pin connected to the metal case of the device , what 's that pin electrically connected to?
     
  5. praondevou

    AAC Fanatic!

    Jul 9, 2011
    2,936
    488
    Depends on the device. Could be part of a filter for example.
    http://www.exergia.info/Lightning/lightning7.htm
     
  6. yassser

    Thread Starter Member

    Jul 25, 2011
    91
    0
    what about motor overload protection elements , I've seen one today , but its for AC motors , I asked if there is one for dc motors , but I couldn't find one , I know that it depends on measuring the temperature caused by the flowing current to determine when to open the circuit , so , it won't be the same for both Ac and Dc .

    so , Is there something else available for DC motors .

    If not , Is there a certain relation between its rated current in AC and the DC current it would permit.
     
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