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G8MNY  > TECH     13.05.24 15:56l 88 Lines 4453 Bytes #8 (0) @ WW
BID : 7626_GB7CIP
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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 �2 (1.414) time bigger than the RMS meter
reading!

325V PK_+    _                                     +
230V____ｳ  /' `\ Sine Wave                 230V DC_ｳ__________
RMS     ｳ ｳ50 Hzｳ  MAINS                           ｳ  D C
     0vﾄｴｳ- - - -ｳ- - - -ｳ                      0vﾄｴ- - - - - -
        ｳ   A C   ｳ     ｳ                          ｳ
        -          \._./                           -
        0      10mS     20mS Time

     POWER   V x I                               POWER  V x I
        ｳ    _       _                             ｳ
        ｳ   / \     / \                            ｳ
   MEAN_ｳ  ﾞ   ﾝ   ﾞ   ﾝ                          _ｳ__________
        ｳ  ﾝ   ﾞ   ﾝ   ﾞ                           ｳ
        ｳ_/_ _ _\_/_ _ _\_                         ｳ_ _ _ _ _ _
          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.

        ____                                  =====             ___   =====
    ﾄﾄﾄｴ____ﾃﾄﾄﾄ        ﾄﾄﾄﾄｴﾃﾄﾄﾄﾄ         ﾄﾄﾄ())))ﾄﾄﾄﾄ      ﾄﾄｴ___ﾃﾄﾄ())))ﾄﾄ
    Pure Resistive     Pure Capacitor       Pure Inductor         Complex
V    _                   _                   _                   _
ｳ  /' `\            ｳ  /' `\            ｳ  /' `\            ｳ  /' `\
ｳ ｳ     ｳ           ｳ ｳ     ｳ           ｳ ｳ     ｳ           ｳ ｳ     ｳ
ｴｳ - - - ｳ - - - ｳ  ｴｳ - - - ｳ - - - ｳ  ｴｳ - - - ｳ - - - ｳ  ｴｳ - - - ｳ - - - ｳ
ｳ         ｳ     ｳ   ｳ         ｳ     ｳ   ｳ         ｳ     ｳ   ｳ         ｳ     ｳ
ｳ          \._./   -ｳ          \._./    ｳ          \._./    ｳ          \._./

    I IN PHASE          I LEADING 90�       I LAGGING 90�     I @ SOME ANGLE
I    _               _               _           _                _
ｳ  /' `\            ｳ `\           /'   ｳ      /' `\        ｳ   /' `\
ｳ ｳ     ｳ           ｳ   ｳ         ｳ     ｳ     ｳ     ｳ       ｳ  ｳ     ｳ
ｴｳ - - - ｳ - - - ｳ  ｴ - -ｳ - - - ｳ      ﾅ - -ｳ - - - ｳ - -  ﾅ ｳ - - - ｳ - - -
ｳ         ｳ     ｳ   ｳ     ｳ     ｳ       ｳ   ｳ         ｳ     ｳｳ         ｳ     ｳ
ｳ          \._./    ｳ      \._./        ｳ_./           \._  ｳ           \._./
 No Current @ 0V     + max current @ 0V  - max current @ 0V   Some current @ 0V

Power_       _        + & - Power         - & + Power         - & + Power
ｳ   / \     / \    +ｳ Zero Net power   +ｳ Zero Net Power   +ｳ   _       _
ｳ  ﾞ   ﾝ   ﾞ   ﾝ    ｳ  _       _        ｳ      _       _    ｳ  / \     / \
ｳ  ﾝ   ﾞ   ﾝ   ﾞ    ｳ / \     / \       ｳ     / \     / \   ｳ ﾞ   ﾝ   ﾞ   ﾝ
ｳ_/_ _ _\_/_ _ _\_  ｳ  _ ﾝ _ ﾞ _ ﾝ _    ｳ  _ ﾞ _ ﾝ _ ﾞ _ ﾝ  ｳ ﾝ _ ﾞ _ ﾝ _ ﾞ _
ｳ Always Positive   ｳ    ﾞ   ﾝ   ﾞ   ﾝ  ｳ    ﾝ   ﾞ   ﾝ   ﾞ  ｳ/     \_/     \_/
ｳ                   ｳ     \_/     \_/   ｳ \_/     \_/       ｳ some net power
ｳ                  -ｳ Equal + - power  -ｳ Equal + - power  -ｳ

  Power Factor 1.0    Power Factor  0.0   Power Factor 0.0    Power Factor 0.7

PHASE                  I                                        Current
      <-.             /ｳ\ Current           ﾚﾄﾄﾄﾄﾄﾄﾄ>V          Lagging
Rotation `\            ｳ  Leading           ｳ90� Current      ,ﾄﾄﾄﾄﾄﾄﾄﾄ>V
           |           ｳ90�                 ｳ    Lagging       `-._  � Angle
   o ﾄﾄﾄﾄﾄﾄﾄ>V & I     ﾀﾄﾄﾄﾄﾄﾄﾄﾄ>V         \ｳ/                     `->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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