PDA

View Full Version : whare to buy...s202s11 "Solid State Built-in snubber ci



riteshjain_82
06-19-2006, 04:47 PM
hi to all
actually i need the "s202s11 " it is a Solid State Built-in snubber circuit.
kindly tell me from whare i can buy it..
it will be good if it from bombay...
thanking you
[/img][/b]

docel
06-19-2006, 09:21 PM
Hi
What is the purpose and/or application of this "solid state snubber" ? And why the exotic component?

An excellent snubber can be designed with discrete RC and diode combo.....

devpriya
06-20-2006, 04:25 PM
Docel ...... I am curious ..... What is a snubber ? Please put some light on it

docel
06-20-2006, 05:06 PM
All inductive loads produce back emf while switched on or off.
1. The current produces a Magnetic field, which is nothing but the converted electrical energy in a 'stored state'.
2. When the tthe emf is removed, the magnetic field will collapse, hence inducing an emf.
3. Any conductor present near a varying magnetic field will have an emf induced in it.
4. This emf will be opposite in sign polarity. The emf can exist ONLY when Current flows in a cunductor (from 0 to maximum and vice versa).

5. This current cannot be static and MUST go somewhere. It usually does, across the breaking contacts of the switch, conductors etc.,

6. Since it cannot be stored, and the contacts are moving apart, the current 'flashes' across the gap, in a tremendous display of fire and heat- the spark. The faster the breaking contact, the higher is the emf produced to induce the spark.

7. This spark is produced at the contacts ( of relays, commutataor brushes, mechanically; between electrodes of an active device- collector to emitter, source to drain etc,.)

8. The spark will destroy the mechanical contacts resulting in relay contact failure or a welded contact pair.

9. The dissipation of this 'induced emf' is always greater than the applied emf. A 1.5VDC source across a coil will induce an emf of several thousand volts.
10 This high voiltage will destroy the components, both active and passive. The destruction is further complimented by the 'reverse polarity' nature of the back-emf.

Now. semiconductor PN junctions have a reverse breakdown limit. The FET and MOSFETs have an even critical rev. breakdown tolerance.
If the back emf is not removed or prevented, it will burn the junction, in some microseconds.

The SNUBBER CIRCUIT is just a shunt, that will bypass the back-emf, hence suppressing the spark (Spark suppressor) from dissipating dangerously.

A single reverse-biased diode or a series RC network will take care of the back emf. They will reduce the emf level due to the RC time constant, and provide alternative path to the reverse current.

Simply speaking: Remember the difference between L293 and L293D??

The Snubber simply 'snubs ' the spark from igniting!!

(dont know what this is doing in the 'buy and sell'forum)

docel
06-20-2006, 05:14 PM
Most of L293 burnouts are due to this lack of diodes or at least a capacitor across the motor terminals!!!!!!

devpriya
06-20-2006, 05:30 PM
Yes and this is why L293 s are burning while L293D s are not for frequent :D

docel
06-20-2006, 05:33 PM
D stands for L293 with built-in Diodes :wink: :wink:

devpriya
06-20-2006, 05:42 PM
Hey Doc !

Thanks a lot for the much needed tutorial on Snubber ...... I think this was the reason my MOSFETs were gettin really heatened up in my custom made H-Bridge motor driver, I tried to dissipate the current using only a resistor :( ..... Hehe.... Information Science solution to electronics problem :P

riteshjain_82
06-23-2006, 02:35 PM
8O ok .understood..............
but dear this is not at all what i want..
the main reason is that this relay is very compact an small.
and i am trying to make kit as small as possible .that's why i need this compact snubber.......
otherwise i know that ...it can be made simply by one opto like moc3021 and a triac bt139.........
correct?
so kindly tell me whare can i get it? :)

docel
06-23-2006, 05:15 PM
My dear riteshjain_82.

What are you talking about???
Do you know what yiou are talking about???

Guys! Do you know what he is talking about???

:evil: :evil:

riteshjain_82
06-24-2006, 11:23 AM
SORRY IF I SAY SOMETHING WRONG
BUT I WANT NLY ABOUT THE THE PLACE WHARE I CAN GET THE RELAY"S202S11"[/img]

docel
06-24-2006, 03:26 PM
OK ritesh, Please dont get annoyed.
It would be nice if you read and check your post before submitting, you wont get jumped upon by people like me! ( Read your posts and tell me if I'm wrong )
I checked on all my suppliers in Bangalore: no luck with the SIP version..

What Current are you switching?? Is it for replacement? It could be available in 2weeks time.

riteshjain_82
06-26-2006, 09:01 PM
thanx for your efforts
i am very happy to say that still i couldn't get it
but i got it's equvalent "s202se1"..both ratings are same..
i got it from mumbai at rs 350

riteshjain_82
06-26-2006, 09:10 PM
thanx for your efforts
i am very happy to say that still i couldn't get it
but i got it's equvalent "s202se1"..both ratings are same..
i got it from mumbai at rs 350