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David
Joined: 03 Oct 2006
Posts: 12
Location: Houston, Texas
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 Posted:
Tue Jan 16, 2007 2:34 am Post subject:
How can current get ahead of voltage? |
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How can current get ahead of voltage, and can you give me an idea of
what this would do to the functionality of a circuit?
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neon
Joined: 25 Feb 2006
Posts: 570
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Wed Jan 17, 2007 7:56 pm Post subject:
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ANGLE OF LEAD when an AC circuit contains capacitance ONLY the voltage lags the current by 90 degrees. or can be stated as the the current leads the voltage by 90 degrees. have your pick.
ANGLE OF LEAD when an AC circuit contain inductance ONLY the changes in current take 90 electrical degrees later then the changes in the voltage. this more comonly expressed as, the current lags the voltage by 90 degrees
either way there is no perfect capacitance or inductance because of actual small resistance therefore there is inpedance to as cos degrees L=RL/ZL.
hope this help you anderstand as a basic for leads/lags. |
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David
Joined: 03 Oct 2006
Posts: 12
Location: Houston, Texas
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Fri Jan 19, 2007 2:23 am Post subject:
How can current get ahead of voltage? |
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Ok, so in order to get them back in sync you'd have to add additional inductance or capacitance which would also add a slight bit more resistance (via impedance) to the circuit. But what affects could this 'unsynced' condition have on a circuits operation?
Thanks,
David
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neon
Joined: 25 Feb 2006
Posts: 570
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Fri Jan 19, 2007 4:23 pm Post subject:
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Tuber
Joined: 06 Mar 2007
Posts: 3
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Sun May 06, 2007 7:43 am Post subject:
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Capacitor:
q=Cv
dq/dt=i=Cdv/dt
The max current to a capacitor occurs at max rate of change of voltage not at max voltage.
With a sinasoidal wave form having peaks above and below zero the same, peak current occurs at zero voltage. Current leads voltage by 90-degrees.
Inductor:
v=Ldi/dt
The max voltage across an inductor occurs at max rate of change of current not at max current. Same form conditions as above, max rate of change of current occurs at zero current. Current lags voltage by 90-degrees. |
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neon
Joined: 25 Feb 2006
Posts: 570
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Fri Jun 01, 2007 2:53 pm Post subject:
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| i hate to tell you tuber but after i read your coments 5 times i still had no idea of what are you saying. you got the formula correct ok but the rest ? i guess i cannot get 45 degree lead or lag only 90 degrees hummmmmm. |
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