Question

Define: i) Firing angle ii) Conduction angle

Answer 1

(i) Firing Angle(): Firing angle is defined as the angle between the instant the SCR would conduct if it would be a diode and the instant it is triggered or fired. Firing angle or delay angle can be defined as the angle measured from the angle that gives maximum average output voltage to the angle when the SCR is actually triggered or fired by gate pulse.

(ii) Conduction Angle (β): Conduction angle is defined as the angle between the instant the SCR is triggered or turned on and the instant at which the SCR is turned off. Assuming that the SCR is turned off naturally at the end of positive half cycle, the relation between the firing or delay angle (α) and conduction angle (β) can be expressed as: 

α + β = π radian or 180^o

Answer 2

(i) Conduction Angle (β): Conduction angle is defined as the angle between the instant the SCR is triggered or turned on and the instant at which the SCR is turned off. Assuming that the SCR is turned off naturally at the end of positive half cycle, the relation between the firing or delay angle (α) and conduction angle (β) can be expressed as:

(ii) Firing Angle(α): Firing angle is defined as the angle between the instant the SCR would conduct if it would be a diode and the instant it is triggered or fired. Firing angle or delay angle can be defined as the angle measured from the angle that gives maximum average output voltage to the angle when the SCR is actually triggered or fired by gate pulse.

Answer 3

i) Firing angle: The firing angle of a thyristor is defined as the angle between the zero crossing of the applied voltage and the instant at which the thyristor is triggered or fired. It is a measure of the point in the alternating current (AC) cycle at which the thyristor begins to conduct current.

ii) Conduction angle: The conduction angle of a thyristor is defined as the angle between the instant at which the thyristor is triggered and the instant at which it is turned off. It is a measure of the duration for which the thyristor conducts current during each AC cycle.