How can you set up an SCR to trigger on more than 90 degrees of phase? As I understand this, you use the potentiometer to decrease the gate current relative to the AC voltage. If you set up high resistance on potentiometer, then you need more voltage to get to the switching current and because more voltage happens later in phase, thus you can switch on specific phase angle. But that should work only when the voltage slope is positive, meaning only on phase angles below 90 degrees, am I right? You cannot switch on the same voltage on the decreasing slope (angle 90 to 180), because the resistor doesn't care about the slope or angle, it only cares about the voltage and all the voltages in angle 90 to 180 happened already earlier in phase.
I had the same question, thanks. As far as I understand thyristors, the firing angle must be between 0 and 90, or on the rising voltage of the positive wave.
The DIAC breaks down at about 32V so the potentiometer slows the rate the capacitor charges. As long as the AC voltage is above 32V the capacitor continues to charge, hence you can fire the DIAC up to the point in the wave the voltage drops below 32V which is quite late in the wave. You can get to past 160 degrees and very little AC through the Triac.
If I were to control the Eddy Current from the inductance coils that you cover in the last part of this video, could I use a Variac and rectify the voltage to get a good control over the field of the coils? I am dealing with 4 big coils connected in series which has a max rating of 250vDC 30A. I figure if I use a variac and rectify the voltage, I can have good analog control over the coils field and strengthen the braking force of the Eddy current it produces to brake a flywheel that is connected to motors for testing HP output. Thank for the video, I am one step closer to figuring this out! Andrew
Can we use this approach to convert AC to DC by chopping only the lower voltage part of the sine wave cycle (using phase angle control first then the diode bridge later and a large capacitor to stabilised the DC output)?
Why all these scr circuits always show 230VAC and not one with 120VAC which is the common voltage in U.S. household. If I was watching other countries video, that is understandable.
@@justinking6541 Very good. How many 230 vac outlet is in your bedroom, your bathroom, your kitchen, your laundry room, your garage which not taken by dedicated circuits belonging to: hot water tank, dryer, heating and air conditioning and stove. If you happen to play with welder and needed power for it in your garage. You have to bring a circuit, and even upgrade your panel to make that possible.
@@alchemy1 most applications of SCR are not using 120v power, they are for heaters and motors which run on 230v. I understand there are lighting applications in residential but most commercial lighting in the US is 277v. Regardless, the voltage does not matter, the purpose of the video is to understand the principals regardless of the voltage. If you don’t have a firm grasp of electrical theory this really isn’t the place to start learning it!
His explanation is better than my university professor. Thank you !!
finally someone i can understand
good video very easy to understand and clear
Why isn't youtube promoting great vids like this? It took me a while to stumble on it.
Thank you for your explanation, keep up the good work
Great explanation very clear to understand.
top explanation. bravo!
Superb explanation
good explanation ,thanks man
Good explain
awesome explanation
How can you set up an SCR to trigger on more than 90 degrees of phase?
As I understand this, you use the potentiometer to decrease the gate current relative to the AC voltage. If you set up high resistance on potentiometer, then you need more voltage to get to the switching current and because more voltage happens later in phase, thus you can switch on specific phase angle.
But that should work only when the voltage slope is positive, meaning only on phase angles below 90 degrees, am I right?
You cannot switch on the same voltage on the decreasing slope (angle 90 to 180), because the resistor doesn't care about the slope or angle, it only cares about the voltage and all the voltages in angle 90 to 180 happened already earlier in phase.
I had the same question, thanks. As far as I understand thyristors, the firing angle must be between 0 and 90, or on the rising voltage of the positive wave.
The DIAC breaks down at about 32V so the potentiometer slows the rate the capacitor charges. As long as the AC voltage is above 32V the capacitor continues to charge, hence you can fire the DIAC up to the point in the wave the voltage drops below 32V which is quite late in the wave. You can get to past 160 degrees and very little AC through the Triac.
6:05 LOL
Thanks a bunch!
If I were to control the Eddy Current from the inductance coils that you cover in the last part of this video, could I use a Variac and rectify the voltage to get a good control over the field of the coils? I am dealing with 4 big coils connected in series which has a max rating of 250vDC 30A. I figure if I use a variac and rectify the voltage, I can have good analog control over the coils field and strengthen the braking force of the Eddy current it produces to brake a flywheel that is connected to motors for testing HP output. Thank for the video, I am one step closer to figuring this out!
Andrew
Awesome
Can we use this approach to convert AC to DC by chopping only the lower voltage part of the sine wave cycle (using phase angle control first then the diode bridge later and a large capacitor to stabilised the DC output)?
well explained
Thanks sir, if the firing angle equal 180 how can I draw the waveform of output current and voltage.
Hello,
Thank you for the video!
I have a questions
Does 2 thyristors and 2 sinus power supplies create a half wave or a full wave?
Sir This circuit is applicable for smooth start of single phase induction motor.....
Formula to find firing angle
How do you control the firing angle ?
Can we fire scr at 0 degree
Why all these scr circuits always show 230VAC and not one with 120VAC which is the common voltage in U.S. household.
If I was watching other countries video, that is understandable.
230 vac is in every household of America!
@@justinking6541 Very good.
How many 230 vac outlet is in your bedroom, your bathroom, your kitchen, your laundry room, your garage which not taken by dedicated circuits belonging to: hot water tank, dryer, heating and air conditioning and stove.
If you happen to play with welder and needed power for it in your garage. You have to bring a circuit, and even upgrade your panel to make that possible.
@@alchemy1 most applications of SCR are not using 120v power, they are for heaters and motors which run on 230v. I understand there are lighting applications in residential but most commercial lighting in the US is 277v. Regardless, the voltage does not matter, the purpose of the video is to understand the principals regardless of the voltage. If you don’t have a firm grasp of electrical theory this really isn’t the place to start learning it!