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What is the name of the scr or triac triggering system that triggers the output device at the same point on each ac cycle?
Diac
Why we don't use triac in case of ac controlled rectfier rather than scr?
A TRIAC does not have a symmetrical turn-on point in the opposite quadrant. This will introduce a DC bias, which you probably don't want. You can use an SCR, and then add diodes to allow it to operate in the opposite quadrant, or you can use two SCR's. Alternatively, you can use a DIAC in the TRIAC's gate circuit to balance the turn on point.
Where does a SCR differ from a power transistor in operation?
thyristor can be scr or triac scr is strictly dc a triac is back to back scr's with a common gate two scr's back to back can be gated independently scrs cost less than triacs an scr can be combined with a full wave bridge to make an equivalent to a triac but this gives an additional 1.5V forward voltage drop
What is SCRS..?
A SCR is a Silcon Controlled Recifier. It is a four layer device that can be conceptually considered to be two transistors in latch up configuration. (Though not exactly) For an SCR, there will be no conduction between anode and cathode until the gate / cathode junction is biased on. At that point, the SCR will latch up and conduct from anode to cathode, regardless of further changes on the gate. This condition will persist until the anode / cathode voltage drops to zero. The SCR can be used as a half wave dimmer in an AC circuit. If you want full wave operation, you need to use a bridge rectifier around the SCR, or use a TRIAC/DIAC circuit.
What is a DIAC?
Diac is a bidirectional electronic switch that can pass current in either directions according to the polarity applied on it.
Can ujt be used to trigger scr?
no
What is the name of the scr or triac triggering system that triggers the output device at the same point on each ac cycle?
Diac
Define latching current in scr?
Latching Current is the minimum current needed on the gate to fire or trigger an SCR.
What is the difference between a DIAC and a TRIAC?
A DIAC is simply a diode that breaks down at predictable voltage.A TRIAC is a 3 terminal device that will conduct whether the anode is at a positive or a negative potential, controlled by a gate.Another answerThey are AC versions of the SCR and diode respectively. Do you need more details?
What is minimum firing angle?
It means the minimum current can trigger the SCR to operate.
Why we don't use triac in case of ac controlled rectfier rather than scr?
A TRIAC does not have a symmetrical turn-on point in the opposite quadrant. This will introduce a DC bias, which you probably don't want. You can use an SCR, and then add diodes to allow it to operate in the opposite quadrant, or you can use two SCR's. Alternatively, you can use a DIAC in the TRIAC's gate circuit to balance the turn on point.
Application of diac?
The diac acts like an open-circuit until its switching or breakover voltage is exceeded. At that point the diac conducts until its current reduces toward zero (below the level of the holding current of the device). The diac, because of its peculiar construction, does not switch sharply into a low voltage condition at a low current level like the SCR or triac. Instead, once it goes into conduction, the diac maintains an almost continuous negative resistance characteristic, that is, voltage decreases with the increase in current. This means that, unlike the SCR and the triac, the diac cannot be expected to maintain a low (on) voltage drop until its current falls below a holding current level.
Where does a SCR differ from a power transistor in operation?
thyristor can be scr or triac scr is strictly dc a triac is back to back scr's with a common gate two scr's back to back can be gated independently scrs cost less than triacs an scr can be combined with a full wave bridge to make an equivalent to a triac but this gives an additional 1.5V forward voltage drop
Difference between diac and triac?
The diac and the triac are used to control the AC lines. The difference is that triac are bigger than diac.
What happens if voltage is constant and current is varying when an scr triggers?
Even if the current is varying,as long as the current reaches the value required to trigger the SCR, it will snap into operation. The SCR will remain in operation until the current through it drops to a value below the holding current.
What is SCRS..?
A SCR is a Silcon Controlled Recifier. It is a four layer device that can be conceptually considered to be two transistors in latch up configuration. (Though not exactly) For an SCR, there will be no conduction between anode and cathode until the gate / cathode junction is biased on. At that point, the SCR will latch up and conduct from anode to cathode, regardless of further changes on the gate. This condition will persist until the anode / cathode voltage drops to zero. The SCR can be used as a half wave dimmer in an AC circuit. If you want full wave operation, you need to use a bridge rectifier around the SCR, or use a TRIAC/DIAC circuit.
Can you use Diac and Triac for dc supply?
The diac conducts in both directions at approximately the same voltage, making it unsuitable in an AC to DC supply. The triac also conducts in both directions, based on a gate voltage which is slightly different in the two usable quadrants. That is why the diac is often used to trigger the triac - it makes the two conduction cycles more symmetric. In both cases, the diac/triac does not make sense for an AC to DC supply, but it works well in an AC voltage regulator, such as a lamp dimmer or motor speed controller.
