Thyristor as switch off device .
Thyristor as switch off device .
(OP)
Hi ,
What code no. of thyristor can be used to protect 220 volt ac 3 amp power source from over current by using thyristor with gate voltage which makes it off not more (5-9)ac volt
note : I want to build this circuit
patrin
What code no. of thyristor can be used to protect 220 volt ac 3 amp power source from over current by using thyristor with gate voltage which makes it off not more (5-9)ac volt
note : I want to build this circuit
patrin





RE: Thyristor as switch off device .
----------------------------------
Sometimes I only open my mouth to swap feet...
RE: Thyristor as switch off device .
There are special versions called GTO thyristors (GTO stands for Gate Turn Off) which have 2 gate signals,; one to turn the thyristor on, another to force it off. These have fallen out of popularity lately because there is a significant ringing effect on the line when they are gated off, which becomes severe electrical line noise that must be dealt with or it will damage other sensitive equipment.
But maybe we are missing your real point because of some translation problems. Are you really asking if you can turn power completely off with a thyristor, or are you wanting to LIMIT the output voltage by phase-angle firing of the thyristor? If you want to do limitation, it is not the thyristor that is different, it is the gating scheme.
RE: Thyristor as switch off device .
"How can I build a thyristor controller that has 220 V AC as an input and outputs between 5 and 9 V AC?"
If that is the meaning of the question, there are two answers:
1 It is simple, use a standard dimmer or one of hundreds of application notes found on internet.
2 Do not do it. Transients are likely to turn on your thyristor and then you will fry your low voltage load. Use a transformer instead.
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Thyristor as switch off device .
I want very fast switch off device please.
AliBaba
RE: Thyristor as switch off device .
"Very fast", as compared to what? Compared to a glacier moving down a mountain, the flow of lava is "very fast". Compared to an electro-mechanical contactor opening, allowing an SCR to self commutate on the next zero cross is "very fast". Compared to that, a Darlington transistor is "very fast".
How much power are you looking to switch as well? If it is .00000001A, then there are a completely different set of tools available to you compared to trying to interrupt 100,000A!
RE: Thyristor as switch off device .
If you want to avoid the zero cross limitation, then you may be able to achieve this with an IGBT.
RE: Thyristor as switch off device .
I want to switch off 220 volt ac for over current of 3 amp,the time of this switch off device should be less than of miniature C.B or fuse time .
RE: Thyristor as switch off device .
There are extremely fast fuses. Fuses that act in a few milliseconds. Do you need faster than that?
If that is so, a thyristor is not an ideal component. You may use an auxiliary thyristor and a capacitor to switch off the main thyristor. Or you may use a GTO (Gate Turn Off) thyristor. But both lead to complex circuitry. An IGBT would be a lot better.
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Thyristor as switch off device .
hope this very clear
RE: Thyristor as switch off device .
If you need faster than a fuse or a CB and the current isn't the result of a short circuit, but beacause you draw slightly more current than your utility allows you to. Then we are talking minutes - not seconds or milliseconds. Your best choice would be a contactor and a circuit that senses current, plus a comparator with a slight delay - let's say a second or two. Make the output from this circuit keep the contactor pulled in as long as there is no more current than 3 A. And drop the contactor if current rises above 3 A for more than a few seconds.
There are some other issues. Like RMS. Inrush curents and such. But you do absolutely not need a very fast switch for this. A contactor is fast enough.
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Thyristor as switch off device .
thanks so much about your nice idea,Iwould know more about comparator property and is it possible to build it my self cause I can not find such component here due to our hard situation .
RE: Thyristor as switch off device .
Here is an example, Siemens relays are available worldwide, but maybe scarce in Iraq at the moment:
Siemens Function Relays The one you could use is shown on pages 8 and 9; the 3UG4622-1AW30. For only a 3A load you could switch your load directly with the contacts of this relay, but I would recommend using this relay to switch another cheaper one that actually switches your power. That way if there is a problem with your power or the suppliers power, it damages only the cheaper relay. There are a lot of other similar products on the market, your challenge will be to find one that you can get your hands on.
Good luck, I feel for you.
RE: Thyristor as switch off device .
I would like to build or buy 6 SSR that are normally closed and trigger on with a 120v input 120 v 2amp out.
Basically I am looking for a NOT circuit for a 120v plug.
I will be using these as a part of a Christmas light show doubling my 6 channels by inverting the output of the prebuilt GE lights and sounds of Christmas. 2 amps should be more than enough for the LED lighting I am using.
any pointers to cheap and easily accessible parts?
RE: Thyristor as switch off device .
I should have typed " SSR that are normally closed and trigger off with a 120v input for 120v 2amp out.
RE: Thyristor as switch off device .
I do not know of any SSRs that are AC input DC output.
I think you need to come up with an alternative solution.
Can you not use mechanical relays for this short lived application? Most have normally open AND normally closed contacts so you get your inversion automatically.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Thyristor as switch off device .
I have concidered mechanical relays. but what I am really doing is expermenting with this circuit to determine the number of channels and ratings I will need for the one I wish to build next year.
I'm not sure were you got the Idea of Dc out,perhaps the LED load. but the load is a 120v 60hz A/C load. well technicly The LED's will only draw in one direction I don't want to create a latched circuit.
Thank you for taking your time,
RE: Thyristor as switch off device .
Yeah, I was thinking LEDs => DC.
You can get SSRs that are AC(control) AC(output) but they still aren't negative logic.
None of this is a problem if you were building from scratch your own product but, off-the-shelf...
Okay what you need is two SSRs, one to shunt the control signal of the second. Something like:
http://w
You set up the control inputs of the the second SSR to be in series with a light bulb. So as hooked up the supply Hot runs thru the lamp to the the second SSR's control input and from the second control input to the neutral. Now just sitting there with the power applied the second SSR is ON its controlled output closed and running whatever.
Now you send your controlling signal to the control input of the first SSR. Whenever your control signal is ON the output of the first SSR is ON (more correctly, closed).
Hook the output of the the first SSR across the input terminals of the second SSR.
The idea here is that when the first is ON the input to the second is shunted or shorted. This would rob the second SSR of its control signal. The lamp is needed because if you shorted the full AC power running the second SSR it would blow something up. (A fuse hopefully)
The lamp will be dim when the first SSR is non-activated and the only current is the 2 or 4mA needed to activate the second SSR. Once the first SSR is activated, shorting the second's control inputs, the lamp will go to full brightness and the second SSR will shut OFF.
Pitfalls. The first SSR will likely need to be a snubberless output type or the current that normally leaks thru the snubber circuitry may be enough to turn OFF the second SSR's control input regardless of the control signals sent into the first SSR.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Thyristor as switch off device .
Is this the case ?
RE: Thyristor as switch off device .
Beats me JayCarp. By now he has probably grown old and died.
Mayhaps you were confused by his initial nonsensical "ON triggered ON" that he ultimately corrected to a true normally ON/OFF situation.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com