# Firing angle Delay

#### Littlehajime

Joined Jun 21, 2007
4
i'm new into power electronic
and i'm assign to do some research about
FIRING ANGLE DELAY

anyone able to explain to me what is it ? and how does it work ?

#### Papabravo

Joined Feb 24, 2006
21,225
If you consider a sine wave, that can be represented by the function:
Rich (BB code):
V(t) = A*sin(wt)

where A is the amplitude, w is the radian frequency, and t is time.
Each value of t when multiplied by w represents an angle. To change the amount of power present in a sine wave you can change the value of A which may be undesireable or you can set the value of A to zero for some part of the cycle. The resulting waveform looks like a step function at the firing angle, and like a sine wave until the next zero crossing.

The Root Mean Square(RMS) value of the resulting waveform will be less than the RMS value of the full waveform.

#### Littlehajime

Joined Jun 21, 2007
4
woah ~~~
dont really get what u mean =)

i was told to design a circuit tat able to adjust firing angle
i don't really understand what is a FIRING ANGLE ?

#### Papabravo

Joined Feb 24, 2006
21,225
I told you what a firing angle was. It is the angle on the sine wave where a switch turns on. The switch turning on, like any switch, allows current to flow. What was wrong with the explanation? If you didn't understand it, then I think you will have great difficulty in designing a circuit.

#### recca02

Joined Apr 2, 2007
1,212
i will try though i have a little understanding of the topic.
firing angle is the angle of the signal/supply at which u switch your scr to act as normal diode. the signal might be a sinusoidal one. and as value of sine changes with angle . we can adjust the power delivered by the wave by turning the scr on at different angle of the sine wave. the portion for which it remains off no power will be delivered.

#### Papabravo

Joined Feb 24, 2006
21,225
I guess the OP will have to weigh in on the clarity of that explanation in contrast to the others.