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1. 전압 ( Voltage )전압은 AC측정의 가장 기본이다. 간단하게 말해서, 전압은 전원과 부하를 교차하여 측정된파형의 크기이다. 거기에는 다섯 종류의 AC 전압 측정값이 있다.즉, 첨두값, 첨두에서 첨두의 값, 평균값, RMS값과 순시값이다.물론 RMS값이 가장 보편적인 것이다.전압을 측정하거나 그것을 거론할 때 가장 일반적으로 사용하는 것은 RMS 값이다.
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C. Voltage )
AC . ,
. AC .
, , , , RMS .
RMS .
RMS .
. Current ) . .
.
. Frequence ) AC .
, 1 .
. Phase Angle and Power Factor ) AC .
(0~360 ) (0~2 ) .
, (volt) 0-360 2 .
.
0-360 2 .
.
( ) ( ) ,
( ) ( ) .
.
(degree) (phase angle).
.
AC , (cos) .
PF = cos 0 90 Radians .
. Watts and Vars ) (P) .
(P=EI).
X X (cos)
. (P=EIcos).
( )
2
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.
X ( ) .
0 ( ) cos 1 P=EI .
.
.
( ) .
.
, ?
. . Watthours) Varhours)
,
. ,
.
.
100 watt 1 100wh .
10,000vars(10Kvars) 24 240KVARHs
.
.
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AC
.
AC
. , , , , ,
.
AC
.
AC , , , AC
.
1. ?
* .
* .
* .
* .
2. ?
*
* PT CT
*
*
*
*
*
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Cccuracy ) : .
pparent Power ) : (Cos ) (VA) verage Value ) :
. , 0.637 .
alanced Load ) : 2 (1 3 , 3 3 , 3 4 ) AC .
Burden : . .
I x Z= VA I =
Z =
. .
E / Z= VA
E =
Z =
.
CT : AC . (Current Transfomer)CT Ratio : 2 1 .Error : ( ) .Frequence : 1 . (cycle/second)Harmonic :
.
Harmonic distortion : .
SCR Triac .
Hertz :High Voltage : 15KV 250KVHorse Power : 1HP = 746Watts .
.
Inductor : ( ) .
. , .
Killowatt : 1000Watt :WKillowatthour : 1 1000wattLagging Current : .
90 . , ,
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.
Leading Current : . 90 .
Low Voltage : 600voltMidium Voltage : 600volt 15kvOhm s Law : DC
V = I R, I = R/V
AC
Power Factor = COS = P/V x I
Z = V/I = P / I x C OS
I = V/Z = P/V x COS
V = IZ = P /I x C OS
P = I x Z x COS = V x I x COS Phase Angle : , . -
0 P.F = 1 .
-
90 P.F = 0 .
0 COS = 1, P=VI .
90 COS = 0, P=0 .
P = V x I x COS . COS power factor .
Power Factor P.F) : P.F AC cosin
VICOS P.F =
VI
P.F :
VICOS :
VI :
V :
I :
Primary : . ( 1 )
Reactive Power : . (VAR )VAR = V x I x SIN
R M S : Root mean square . . RMS ( ) watt .
DC .
RMS = 0.707 x
R T U : Remote Terminal Unit .
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. RTU SCADA SYSTEM .
SCADA : supervisory control and data aquisition.
.
Secondary : . ( 2 )
Sinusoidal Voltage and Current : : 0.707 x = RMS
: 0.637 x
True Power : . watt .WATT = V x I x COS
nbalanced Load ) : 2 (1 3 , 3 3 , 3 4 )
.
V.A : Volt Ampare . volt ampare .
VAR : VA . wattWATT : 1 1
1A 1 .
watt . "W"
Watthour : 1 watt 1 . "WH" .
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C .
.
: ,
, .
AC .
AC .
. .
2 .
(220)volts .
, (220)VAC 110V .
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. 220VAC ,
1/2 . 180 .
.
.
3HP 3 3 .
(A B, B C, A C) 220VAC 440VAC .
(Y) .
AC .
. , 3
.
) : 380VAC (A-B, B-C, A-C) : 380/ 3 = 220VAC (A-N, B-N, C-N)
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) AC
AC .
.
) AC
AC AC .
Ohm's Law : = X (E=IR). ,
.
AC 10ohm 15ohm 110 Volt AC
.
E= IR
110 VAC = I ( 10 Ohm) + (15 Ohm)
110 VAC = I ( 25 Ohm)
110VAC= I
25Ohm
4.4 Amps = I 4.4 A .
:
E= IR
E= ( 4.4 Amps) (10 Ohm) = 44 Volts AC
E= ( 4.4 Amps) (15 Ohm) = 66 Volts AC
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Kirchoff's Voltage Law .
0 .
44 VAC + 66 VAC = 110 VAC ( )
110 VAC .
,
.
( ),
.
. 1 . 1 .
CT AC .
.
CT 2 0-1mA DC 4-20mA DC DC
.
DC , , AC
.
. .
( ) VA VA .
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: 10 : 1 : VAp = Ep x Ip = 1000 VA
Ep = 100 VAC VAs = VAp - = 1000 VA
Ip = 10Amps AC Es = Ep / 10 = 10 VAC
= 0 Is = VAs / 10 = 100 Amps
2 2 .
CT :
2 VA .
. : 0.1 Ohm ( )
VA in = 50000 VA ( 100 V, 500 A ) : 1
E = IR, E = 5 Amps x 0.1 Ohm = 0.5 Volts : 2
CT CT , 0
.
CT CT 2
.
100 VAC x CT
500100 VAC x
5
100 VAC x 100 = 10,000 Volts
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CT (arc)
CT , ,
CT 2 .
.
.
:
Motor
) .
(PT) .
DC
(0 1 mA DC 4~12~20 mA DC) .
. 60Hz 5Hz 1 mA DC
60Hz 0 mA DC . 55 Hz -1 mA DC , 65 Hz
+1 mA DC .
4~20 mA DC . 60Hz 12 mADC
(12 mADC 4 mA DC 20 mA DC ) ,
55 Hz 4 mA DC 65 Hz 20 mA DC
) Watt Transducer ) " " . .
.
1 watt 1ohm 1volt 1 amp 1 volt .
AC
P= V x I x .
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,
.
fullscale
.
. 85-150 VAC 0-5
Amp . 0
150 VAC x 5 Amps x 1 = 750 watts .
, 110VAC 150volts
CT .
, (per element)
full scale 500watts .
. (single element) fullscale 500 watts , .
output range x 0.616 = 308 watts
* 0~1 mA DC
1 mA DC x 0.616 = 0.616 mA DC
* 4~20 mA DC16 mA DC x 0.616 = 9.856 mA DC + 4 mA DC = 13.856 mA DC .
( 0 )
uti-Element Transducer fullscale2 Element Transduce
2 3 3 .
Measured watts 308= = 0.616
fullscale watts 500
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2 2 . 1 500watts
1000 watts .
3 : P = 3EIcos .
, 2
. fullscale 1000watts 951watts
3 Element Transducer
3 3 4 . .
.
full scale 1500 watts . 1666, 2000, 4000watts
.
) . ;
VAR = V x I x sin .
30 (Lagging) .
P= VI x cos (cos ) ,
, .
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watts .
.
.
1, 2 3 . ,
PT's CT's .
.
. motor
0.6 (Lagging)
.
.
.
. , .
, . ,
.
.
, .
) .
.
, 1000 KWH/day .
.
? (
) .
15 . 15
X KWH , Y .
,
.
,
.
, (
) . (Load shedding) .
.
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.
.
( ) ( )
.
) . 1 VARH 1 VAR 0.1
10 VAR
15
.
,
.
, .
.
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C
.
AC
AC .
AC
. , , AC-DC
.
AC . , .
.
.
, .
,
.
.
,
.
, 1
.
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,
.
.
.
90 , 0 .
90 0
.
.
, .
,
.
.
.
.
.
, .
.
, .
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11 .
.
.
,
2% .
50 70 Hz .
AC
.
.
.
5 volt ,
.
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.
?
1. .
2. .
3. .
4. 50 70 Hz
1% 3% .
5. AC 6 7
.