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G8MNY > TECH 09.07.08 18:42l 126 Lines 5726 Bytes #999 (0) @ WW
BID : 61545_GB7CIP
Read: GUEST OE7FMI
Subj: AC 3 Phase Power
Path: DB0FHN<DB0FOR<DF0ANN<DB0MRW<DB0ERF<DB0FBB<DB0IUZ<DB0OVN<DB0GOS<ON0AR<
GB7CIP
Sent: 080709/0859Z @:GB7CIP.#32.GBR.EU #:61545 [Caterham] $:61545_GB7CIP
From: G8MNY@GB7CIP.#32.GBR.EU
To : TECH@WW
By G8MNY (Updated Feb 08)
(8 Bit Graphics use code page 437 or 850)
3 PHASE POWER
This is how AC power is normally generated & distributed, it is more efficient
than other AC systems, except for DC that is the most efficient, but difficult
& costly to transform the voltage at high power.
The wire colour scheme may differ between countries & also the voltage!
The phase angle between phases is 120ø, because of this the voltages are added
up vectorialy, so at first sight 2x 230V does not make 415V between 2 lives.
You divide by û3 (1.732) to get the line to neutral voltage.
Line
BROWN ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ STAR LOADS DELTA LOADS
(red) /³\ /³\ /³\ o
415V | | Brown Brown
\³/ 415V | Load o
BLACK ÄÄÄÄÄÄÄÄÄÄÄÄÄ | ³ /60ø\
(yellow) /³\ | /³\ | 120ø o 120ø 400V 400V
415V | | | / \ Load Load
\³/ \³/ | | Grey 120ø Black / 60ø 60ø \
GREY ÄÄÄÄÄÄÄÄÄ | | Load Load o______ 400V ______o
(blue) /³\ | | o o Grey Load Black
230V 230V 230V If loads balanced No Neutral
\³/ \³/ \³/ centre = neutral &
BLUE ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ loads all get 230V
(black) (neutral)
NEW COLOUR HAZARDS !
New EU colours are Brown Black Grey for Lives & Blue Neutral
replace red yellow blue for Lives & black Neutral. Green/Yel earth.
N.B. the lethal change for both BLACK & BLUE colours!
Also note the colour layout of new 3 phase 4 core cable means, that a joint can
not be straight to an old cable & bigger joints casings will be needed to allow
for at least 2 cores to be bridged!
Single phase will change from Red live, Black Neutral to Brown & Blue
respectifully. But highly confusing in a 3 phase board with both old black
wire loads for Neutrals & Black Bus feed for live! Brown & Blue sleeves are to
be used over Red & Black wires!
3 PHASE TRANSFORMERS
Like any transformer the voltage can be changed, or isolated etc. The
difference being that 3 legs of the transformer carry the windings rather than
just the middle. ÚÄÄÄÄÄÄÄÄÄÄÄ¿ The winding connections can be either STAR or
³ ÚÄÄ¿ ÚÄÄ¿ ³ DELTA or combinations of both.
ÚÁÄÁ¿ÚÁÄÁ¿ÚÁÄÁ¿ When cross connected star-delta a rotation of
Windings->³ 1 ³³ 2 ³³ 3 ³ 90øin phase occurs. (eg 30ø from other phases)
ÀÂÄÂÙÀÂÄÂÙÀÂÄÂÙ .
Laminated ³ ÀÄÄÙ ÀÄÄÙ ³ | or / \ becomes _ / or /'³
Core ->ÀÄÄÄÄÄÄÄÄÄÄÄÙ / \ '---' \ '\,³
(due to magneto striction audio the hum given off from the steel is @ 300Hz)
3 PHASE RECTIFICATION
With rectification 3 diodes gives about 30% ripple at 150Hz (3x supply) the
ripple is not much as singe phase, as some of the 120ø voltages overlap.
___________________
_³_ _³_ _³_ /|\
/_\ /_\ /_\ | 100% ´ _.-._ _.-._ _.-._ Â Ripple
R ÄÄÄÙ ³ ³ Raw 70%_³ / \ / \ / Á
³ ³ DC ³ ³ ³ ³
Y ÄÄÄÄÄÄÄÄÄÙ ³ | ³ ³ ³ ³ ³ ³
³ | ³³ ³ ³ ³ ³
BÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ | ÅÄÄÄÄÄÄÄÄÂÄÄÄÂÄÄÄÂÄÄÄÂÄÄÄÂÄ
\³/ 0ø 120 180 240 310 360ø
NÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
3 PHASE BRIDGE RECTIFIERS
Only 6 diodes produce a 3 phase bridge & that gives about 14% @ 300Hz (6x
supply) ripple peak to peak, as more of the 60ø voltages overlap.
________________
_³_ _³_ _³_ /|\
/_\ /_\ /_\ | 100% ´ _.-._.-._.-._.-._.-._ Â Ripple
R ÄÄÄ´ ³ ³ | 86% /³ / / \ / \ / \ / \ / ^
³ ³ ³ | ³ ³ ³ ³ ³ ³ ³
Y ÄÄÄ)ÄÄÄÄÄ´ ³ Raw ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³
³ ³ ³ DC ³³ ³ ³ ³ ³ ³ ³
BÄÄÄÄ)ÄÄÄÄÄ)ÄÄÄÄÄ´ | ÅÄÄÄÄÂÄÄÄÂÄÄÄÂÄÄÄÂÄÄÄÂÄÄÄÂÄ
_³_ _³_ _³_ | 0ø 60 120 180 240 310 360ø
/_\ /_\ /_\ \|/
ÀÄÄÄÄÄÁÄÄÄÄÄÁÄÄÄÄ
12 PHASE RECTIFIERS
With push pull or 3 phase bridge system, & using both star & delta windings
there can effectively be 12 lives that are only 30ø apart. This can also be
achieved with push pull phase on each leg of the transforner.
| \ / \ | /
* + * = *
/ \ | / | \
Using 2x 3 phase bridges or 12 winding & diodes the resultant ripple is only
about 3.6% @ 600Hz, assuming all the voltages are equal! Very little filtering
is then needed for say a 100kW Tx HT supply.
________________________
_³_ _³_ _³_ _³_ _³_ _³_ /|\
Floating /_\ /_\ /_\ /_\ /_\ /_\ |
. RDÄÄÄ´ ³ ³ ³ ³ ³ | 100% ´ _.-.-.-.-.-.-.-.-. = Ripple
/ \ YDÄÄÄ)ÄÄÄ´ ³ ³ ³ ³ | 96% /³ / / /\/\/\/\/\/\/\
'---' BDÄÄÄ)ÄÄÄ)ÄÄÄ´ ³ ³ ³ | ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³
Windings ³ ³ ³ ³ ³ ³ Raw ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³
RSÄÄÄ)ÄÄÄ)ÄÄÄ)ÄÄÄ´ ³ ³ DC ³³ ³ ³ ³ ³ ³ ³ ³ ³ ³ ³
| YSÄÄÄ)ÄÄÄ)ÄÄÄ)ÄÄÄ)ÄÄÄ´ ³ | ÅÄÄÂÄÂÄÄÄÂÄÄÄÂÄÄÄÂÄÄÄÂÄ
/ \ BSÄÄÄ)ÄÄÄ)ÄÄÄ)ÄÄÄ)ÄÄÄ)ÄÄÄ´ | 0ø 30 60 120 180 240 310ø
_³_ _³_ _³_ _³_ _³_ _³_ |
/_\ /_\ /_\ /_\ /_\ /_\ \|/
ÀÄÄÄÁÄÄÄÁÄÄÄÁÄÄÄÁÄÄÄÁÄÄÄÄ
Why Don't U send an interesting bul?
73 De John, G8MNY @ GB7CIP
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