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home | newest check | boards | help index | log | ps | userlogin | send sysop | slog | status forward | bcm news | users | version | remove cookieG8MNY > TECH 13.05.24 15:56l 88 Lines 4453 Bytes #9 (0) @ WW BID : 7626_GB7CIP Subj: AC Theory Path: JH4XSY<JE7YGF<LU4ECL<LU9DCE<GB7YEW<GB7CIP Sent: 240513/0650Z @:GB7CIP.#32.GBR.EURO #:7626 [Caterham Surrey GBR] $:7626_GB From: G8MNY@GB7CIP.#32.GBR.EURO To : TECH@WW By G8MNY (Updated Mar 08) (8 Bit ASCII graphics use code page 437 or 850, Terminal Font) RMS is the DC equivalent power of AC, & for a sine wave is 70.7% of the peak value. e.g. the peak value is ū2 (1.414) time bigger than the RMS meter reading! 325V PK_+ _ + 230V____³ /' `\ Sine Wave 230V DC_³__________ RMS ³ ³50 Hz³ MAINS ³ D C 0vÄ“³- - - -³- - - -³ 0vÄ“- - - - - - ³ A C ³ ³ ³ - \._./ - 0 10mS 20mS Time POWER V x I POWER V x I ³ _ _ ³ ³ / \ / \ ³ MEAN_³ Ž Ż Ž Ż _³__________ ³ Ż Ž Ż Ž ³ ³_/_ _ _\_/_ _ _\_ ³_ _ _ _ _ _ Power Sine Wave @ 2x Frequency Unlike DC circuits in AC circuits the power is the mean of the Instantaneous Power which is made from the instantaneous Voltage X instantaneous Current. For complex non resistive power loads it is usual to use a term Power Factor to describe the rating factor to be applied to the RMS Volts X RMS Amps to get the true power rating. Some items are rated in Watts & some in VA depending on which is the safer limit for that item. e.g. a kettle is rated in watts & a transformer is rated in VA. At power stations the amount of Volt Amp Reactive (VARS) is monitored as an indication of how much wasted energy flows to & from the customers, just heating up the transmission system. As the transmission lines are capacitive some inductive power factor is a good idea as it tunes out this capacitance. ____ ===== ___ ===== ÄÄÄ“____ĆÄÄÄ ÄÄÄÄ“ĆÄÄÄÄ ÄÄÄ())))ÄÄÄÄ ÄÄ“___ĆÄÄ())))ÄÄ Pure Resistive Pure Capacitor Pure Inductor Complex V _ _ _ _ ³ /' `\ ³ /' `\ ³ /' `\ ³ /' `\ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ “³ - - - ³ - - - ³ “³ - - - ³ - - - ³ “³ - - - ³ - - - ³ “³ - - - ³ - - - ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ \._./ -³ \._./ ³ \._./ ³ \._./ I IN PHASE I LEADING 90ų I LAGGING 90ų I @ SOME ANGLE I _ _ _ _ _ ³ /' `\ ³ `\ /' ³ /' `\ ³ /' `\ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ “³ - - - ³ - - - ³ “ - -³ - - - ³ Å - -³ - - - ³ - - Å ³ - - - ³ - - - ³ ³ ³ ³ ³ ³ ³ ³ ³ ³³ ³ ³ ³ \._./ ³ \._./ ³_./ \._ ³ \._./ No Current @ 0V + max current @ 0V - max current @ 0V Some current @ 0V Power_ _ + & - Power - & + Power - & + Power ³ / \ / \ +³ Zero Net power +³ Zero Net Power +³ _ _ ³ Ž Ż Ž Ż ³ _ _ ³ _ _ ³ / \ / \ ³ Ż Ž Ż Ž ³ / \ / \ ³ / \ / \ ³ Ž Ż Ž Ż ³_/_ _ _\_/_ _ _\_ ³ _ Ż _ Ž _ Ż _ ³ _ Ž _ Ż _ Ž _ Ż ³ Ż _ Ž _ Ż _ Ž _ ³ Always Positive ³ Ž Ż Ž Ż ³ Ż Ž Ż Ž ³/ \_/ \_/ ³ ³ \_/ \_/ ³ \_/ \_/ ³ some net power ³ -³ Equal + - power -³ Equal + - power -³ Power Factor 1.0 Power Factor 0.0 Power Factor 0.0 Power Factor 0.7 PHASE I Current <-. /³\ Current ŚÄÄÄÄÄÄÄ>V Lagging Rotation `\ ³ Leading ³90ų Current ,ÄÄÄÄÄÄÄÄ>V | ³90ų ³ Lagging `-._ ķ Angle o ÄÄÄÄÄÄÄ>V & I ĄÄÄÄÄÄÄÄÄ>V \³/ `->I I See my Tech buls "Maplin Mains Meter 2000MU-UK", "UK 13A Fused Mains Plug", & "Tuned Circuit Scope Demo". Why Don't U send an interesting bul? 73 De John, G8MNY @ GB7CIP
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