12-
38
750/760 Feeder Management Relay
GE Power Management
12.5 SENSITIVE GROUND CURRENT
12 S5 PROTECTION
12
c) SAMPLE APPLICATION
The CTs used in this example are 3000/1, 10P10, 15 VA, and the transformer used in the example is an 11
kV / 400V, 2000kVA. At 10P10 the voltage at which the CT will saturate will be 10 x 15 = 150 V. An equivalent
IEEE description for this CT would be 3000/1, C150.
Figure 12–17: SAMPLE APPLICATION
R
CT
= 3.7
Ω
R
L
= 0.954
Ω
assuming 600 feet of #12 wire
X
(
%
) = impedance of transformer = 7% = 0.07
Rated transformer current through wye windings:
Maximum fault current is:
Therefore, the secondary full load current is:
and the maximum secondary fault current is:
A
V
K
/
V
S
ratio of 2 is assumed to ensure operation.
V
S
=
I
f
(
R
CT
+ 2
R
L
) = 77.05 V
V
K
= 2
V
S
= 154.1 V
I
P
2000 kVA
3 400 V
⋅
----------------------------
2887 A
=
=
I
MAXf
I
P
X
%
( )
--------------
2887 A
0.07
-------------------
41243 A
=
=
=
I
SFLC
2887 A
3000
-------------------
0.962 A
=
=
I
Smax
0.962 A
0.07
---------------------
13.74 A
I
f
=
=
=
Содержание 750
Страница 2: ......
Страница 4: ......
Страница 124: ...8 14 750 760 Feeder Management Relay GE Power Management 8 12 INSTALLATION 8 S1 RELAY SETUP 8 ...
Страница 144: ...10 14 750 760 Feeder Management Relay GE Power Management 10 10 MISCELLANEOUS FUNCTIONS 10 S3 LOGIC INPUTS 10 ...
Страница 152: ...11 8 750 760 Feeder Management Relay GE Power Management 11 3 OUTPUT RELAYS 3 7 AUXILIARY 11 S4 OUTPUT RELAYS 11 ...
Страница 216: ...12 64 750 760 Feeder Management Relay GE Power Management 12 9 BREAKER FAILURE 12 S5 PROTECTION 12 ...
Страница 484: ...17 78 750 760 Feeder Management Relay GE Power Management 17 10 PLACING THE RELAY IN SERVICE 17 COMMISSIONING 17 ...
Страница 488: ...A 4 750 760 Feeder Management Relay GE Power Management A 1 FIGURES AND TABLES APPENDIXA A ...
Страница 490: ...B 2 750 760 Feeder Management Relay GE Power Management B 1 EU DECLARATION OF CONFORMITY APPENDIXB B ...
Страница 492: ...C 2 750 760 Feeder Management Relay GE Power Management C 1 WARRANTY INFORMATION APPENDIXC C ...
Страница 502: ...x 750 760 Feeder Management Relay GE Power Management INDEX ...
Страница 503: ...GE Power Management 750 760 Feeder Management Relay NOTES ...