Scr gate characteristic for the circuit what voltage

SCR | Gate Characteristic
For the circuit, what voltage is
required at point X to fire the SCR?

SCR | Gate Characteristic
For the circuit assume the supply
115vrms, I
GT
= 15mA and R
1
=3 kΩ .
What should R
2
be adjusted?
2

SCR | ON & OFF
• Turning ON :
 Supply DC voltage > VBRF.
 Supply appropriate short pulse amount at gate terminal.
 Remains ON due to Regenerative Action.
• Turning OFF :
 Anode Current Interruption  Forced Commutation

SCR | Waveform < 90 º
Conduction Angle, β
Number of degrees in AC cycle
during which the SCR is ON.
Firing Delay Angle, α
Number of degrees in AC cycle
during which the SCR is OFF.
α + β = 180
o
α β
V
AK
V
LOAD

SCR | Waveform > 90 º
?

SCR | Power Computations
Where:
V
avg
= Average Voltage (V)
V
rms
= RMS Voltage (V)
V
p
= Peak Input Supply Voltage (V)
P
avg
= Average Power (W)
P
rms
= RMS Power (W)
R
L
= Load Resistance ( Ω )
α = Firing Delay Angle ( deg or rad )
= 360 ft or 2 π ft
sin 2 α sin 2 α