# Triac RC Calculation

Discussion in 'Electronics Resources' started by gr13, Feb 20, 2012.

Nov 16, 2009
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2. ### gr13 Thread Starter New Member

Nov 16, 2009
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In this circuit, a series resistor-capacitor network creates a phase-shifted voltage for the "gate" terminal of a power-control device known as a TRIAC. All portions of the circuit except for the RC network are ßhaded" for de-emphasis:

Calculate how many degrees of phase shift the capacitor's voltage is, compared to the total voltage across the series RC network, assuming a frequency of 60 Hz, and a 50% potentiometer setting.

Answer :EC phase shift = -76.7 degree

Please let me know involved steps; I am not from electronics - tried 1/2∏fC, but answer was something different than provided in hints!

Thanks

3. ### Jony130 AAC Fanatic!

Feb 17, 2009
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gr13 likes this.
4. ### gr13 Thread Starter New Member

Nov 16, 2009
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Thanks
should we simply put a negative sign for capacitive reactance?

books simply say that it's 90 degree phase shift - is that statement wrongly interpreted by most of us? Or it's only me who is confused

5. ### Jony130 AAC Fanatic!

Feb 17, 2009
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Yes we should.

Yes you are right the books say 90 degree phase for capacitor alone.
So we have 90° phase shift between capacitor current and capacitor voltage. The capacitor current leads the voltage in capacitor.