what are thryistor applications?

Answer 1

Hey cool_alien_frm_mars , you've copied your entire article from the wikipedia page : http://en.wikipedia.org/wiki/Thyristor
.Check out the Applications topic.

Why couldn't you just paste a link?

Answer 2

Thyristors [sp?] are becoming more popular, but most people don't know what they are.
A thyristor is like a transistor, but it handles AC (alternating current) power.
Thyristors are used in a device known as an Inverter, which campers and people living in the hills are probably more familiar with than you city folk. An inverter can take twelve volt DC current (from batteries and/or solar panels) and change it to 115 volt AC current. So if you don't have power lines going to where you live, you can still power devices such as a refrigerator.
Thyristors are found in the UPS (Un-interuptable Power Supply) that many computers are plugged into. Many people mistake these for an ordinary surge protector, but a UPS has batteries and an inverter with thyristors, so your computer will stay on in a blackout for at least fifteen minutes, which is long enough to save your typing or whatever data you have generated.
Thyristor based inverters are also found in emergency lighting and exit signs, which are required by building code to permit the safe evacuation of buildings in an emergency.
Thyristors are also found in the inverters which power Alternating Current Locomotives. These railroad engines may recieve DC (Direct Current) from an onboard generator, or from a third rail. The thyristors in these railroad engine inverters switch power from positive to negative up to 500 Hertz , or 500 cycles per second, which is faster than the 60 Hz current found in houses.
Thyristors are what make converting Direct Current to Alternating Current posible.

Answer 3

Thyristors are mainly used where high currents and voltages are involved, and are often used to control alternating currents, where the change of polarity of the current causes the device to automatically switch off; referred to as Zero Cross operation. The device can be said to operate synchronously as, once the device is open, it conducts current in phase with the voltage applied over its cathode to anode junction with no further gate modulation being required to replicate; the device is biased fully on. This is not to be confused with symmetrical operation, as the output is unidirectional, flowing only from cathode to anode, and so is asymmetrical in nature.

Thyristors can be used as the control elements for phase angle triggered controllers, also known as phase fired controllers.

Thyristors can also be found in power supplies for digital circuits, where they can be used as a sort of "circuit breaker" or "crowbar" to prevent a failure in the power supply from damaging downstream components. The thyristor is used in conjunction with a zener diode attached to its gate, and when the output voltage of the supply rises above the zener voltage, the thyristor opens, shorting the power supply output to ground (and in general blowing an upstream fuse).

The first large scale application of thyristors, with associated triggering diac, in consumer products related to stabilized power supplies within color television receivers in the early 1970's. The stabilized high voltage d.c supply for the receiver was obtained by moving the switching point of the thyristor device up and down the falling slope of the positive going half of the a.c supply input. The precise switching point was determined by the load on the output d.c supply as well fluctuations on the input a.c supply. They proved to be unpopular with the a.c grid power supplier companies because the simultaneous switching of many television receivers, all at approximately the same point in time, introduced asymmetry into the supply waveform and as a consequence injected d.c back into the grid with a tendency towards saturation of transformer cores and overheating. They were largely phased out in this kind of application by the end of the decade.

Snubber circuits
Because thyristors can be triggered on by a high rate of rise of off-state voltage, in many applications this is prevented by connecting a resistor-capacitor (RC) snubber circuit between the anode and cathode terminals in order to limit the dV/dt.