l29 3 ph-ac
DESCRIPTION
TRANSCRIPT
THREE PHASE CIRCUIT ANALYSIS:Unbalanced loads
ELE101/102 Dept of E&E,MIT Manipal 2
Unbalanced delta connected load
240
;120
; 0
phBR
phYB
phRY
VV
VV
VV
BR
BRBR
YB
YBYB
RY
RYRY Z
VI;
Z
VI;
Z
VI
YBBRBRYYBYBRRYR III ;III ;III
BRBRBR
YBYBYB
RYRYRY
ZZ
ZZ
ZZ
ˆ
ˆ
ˆ
ELE101/102 Dept of E&E,MIT Manipal 3
Unbalanced 4 wire star connected load
BBB
YYY
RRR
ZZ
ZZ
ZZ
The line voltages are symmetrical and balanced
ON
R
Y
B
RNV
YNVBNV
BIYI
RI
ROV RZ
yZBZ
B
BNB
Y
YNY
R
RNR Z
VI;
Z
VI;
Z
VI
BYRN IIII
Neutral current
ELE101/102 Dept of E&E,MIT Manipal 4
Unbalanced 3 wire star connected load
BBB
YYY
RRR
ZZ
ZZ
ZZ
240
;120
; 0
phBN
phYN
phRN
VV
VV
VV
The line voltages are symmetrical and balanced
ON
R
Y
B
RNV
YNVBNV
BIYI
RI
ROV RZ
yZBZ
ELE101/102 Dept of E&E,MIT Manipal 5
Method (1) Conversion of star connected load to delta
AZ
BZCZ
ABZ
BCZ
CAZ
B
ACACCA
A
CBCBBC
C
BABAAB
Z
ZZZZZ
Z
ZZZZZ
Z
ZZZZZ
.
.
.
Application of analysis of unbalanced delta connected load
ELE101/102 Dept of E&E,MIT Manipal 6
Illustration:
4510Z 3012Z 012Z CBA
120VV , 0VV ,120VV LCALBCLAB
are connected in star across a 3Φ, 3 wire, 416 volt supply system, the voltages being
Three impedances
Find line currents IA, IB and IC by star delta transformation method
A84.235.15IB
A5.6326A21.11646.26IC
;A993.23IA
Ans: