| Author |
Message |
Nicholas
Joined: 21 Feb 2004
Posts: 78
|
 22 Sep 2004 5:56 Any way to protect TRIAC from exploding when over current? |
|
|
|
| if output overcurrent or even short circuit, the TRIAC would got blown up at once after triggering. any way to avoid this? under resistive or inductive load conditions. Thanks
|
|
| Back to top |
|
 |
pico
Joined: 30 Sep 2001
Posts: 261
Helped: 5
|
| 22 Sep 2004 7:42 Any way to protect TRIAC from exploding when over current? |
|
|
|
| Using fast blow fuse.
|
|
| Back to top |
|
|
rauol
Joined: 02 Oct 2002
Posts: 345
Helped: 11
|
| 22 Sep 2004 8:47 Re: Any way to protect TRIAC from exploding when over curren |
|
|
|
 FAST blow fuses may not protect, there is a class called "Semiconductor Fuse" which blows at a specific I2T rating.
|
|
| Back to top |
|
|
Nicholas
Joined: 21 Feb 2004
Posts: 78
|
| 23 Sep 2004 16:46 Any way to protect TRIAC from exploding when over current? |
|
|
|
| what if I need to monitor the current and safely turn off the TRIAC when needed before it burnout?
|
|
| Back to top |
|
|
maranaza
Joined: 27 Mar 2002
Posts: 51
|
| 23 Sep 2004 18:47 Re: Any way to protect TRIAC from exploding when over curren |
|
|
|
As much as I know, high current semiconductor fuse is more expensive than triac itself. Hence, I don't see good reasons for its use.
I don't understand how do you mean to "safely turn off the TRIAC when needed before it burnout". With another high power fast switch that can withstand short circuit current?
maranaza
|
|
| Back to top |
|
|
tanuki
Joined: 11 Jun 2001
Posts: 80
Helped: 2
Location: Spain
|
| 23 Sep 2004 19:56 Re: Any way to protect TRIAC from exploding when over curren |
|
|
|
Please provide more information: Triac type, load type, nominal load, etc.
Triac's generally can tolerate 20 times overload for one (1) 60Hz full wave cycle.
Fractional phase conduction has even higher overload tolerance (easily exceeding 100 times for small angle conduction cycle).
You can protect your triac and other circuit elements by senseing the overcurrent (using low resistance shunt) and locking out the triac triggering circuit.
A fault indicator and some fauilt reset protocol (time wait, reset button, power removal, etc.) would be nice too 
General circuit usage details :
http://www.epanorama.net/circuits/semiconductor_relays.html#overcurrent
|
|
| Back to top |
|
|
Nicholas
Joined: 21 Feb 2004
Posts: 78
|
| 24 Sep 2004 4:24 Any way to protect TRIAC from exploding when over current? |
|
|
|
| oh, I misunderstood that when overload or short circuit, the TRIAC will go to hell in a very short time before I can do anything to rescue it. Now, I think I can do some detecting job before trigger the TRIAC to avoid short circuit. And for overload, just keep sensing the current all the time.
|
|
| Back to top |
|
|
rauol
Joined: 02 Oct 2002
Posts: 345
Helped: 11
|
| 24 Sep 2004 14:00 Re: Any way to protect TRIAC from exploding when over curren |
|
|
|
 Once a Triac is turned on you have to remove power in DC application or with AC wait for the Zero crossing before u can switch the triac off.
If the cost of the Semiconductor FUSE is not acceptable U can pretty well change the normal fuse and the triac. u can make a pluggable assembly of triac and normal fuse which can be replaced easily.
|
|
| Back to top |
|
|
