Bypass Capacitor Burned

[hareesh_mohan]

Hi Guys ,

I have designed a switch circuit with max load current 12A , input is an automotive battery with 12V ,70A rating . also placed a 100nF bypass capacitor between + and - terminals . but during working this capacitor got burned .. can you tell me the reason and how to fix it .

 

[barry]

If your load is switching on and off rapidly this will cause a current to flow through the cap. You might be exceeding the current handling capabilities of the cap.
What exactly is your load?

Or, if your load is inductive, you could be getting large voltage transients that are damaging the cap.

 

[hareesh_mohan]

If your load is switching on and off rapidly this will cause a current to flow through the cap. You might be exceeding the current handling capabilities of the cap.
What exactly is your load?

Or, if your load is inductive, you could be getting large voltage transients that are damaging the cap.

How we can calculate the current carrying capability of capacitor ...

yes my load is inductive ...Motor is my load .. normal load of 10A and maximum load of 20A

 

[barry]

I'm not really sure what a motor load does to a capacitor; I was thinking more of when you disconnect an inductive load you can generate a very large voltage spike.

 

[bigdogguru]

As barry indicated, you maybe inducing a large Back EMF or Flyback when the power is removed from the motor.

Depending of the type of motor you are utilizing, typically a snubber circuit, MOV or diode is used to prevent such damage.



**broken link removed**


BigDog

 

[hareesh_mohan]

As barry indicated, you maybe inducing a large Back EMF or Flyback when the power is removed from the motor.

Depending of the type of motor you are utilizing, typically a snubber circuit, MOV or diode is used to prevent such damage.



**broken link removed**


BigDog

Already i do have a diode for reverse polarity protection that will serve as a protection for back emf also right ? actually i am just making a proto of automotive power window switch , so my load here is wiper /washer motor