GE Power Management
745 Transformer Management Relay
5-47
5 SETPOINTS
5.6 S4 ELEMENTS
5
The basic operating principle of the percent differential element can be described by the following diagram and
its associated equations:
Figure 5–6: PERCENT DIFFERENTIAL OPERATING PRINCIPLE
Restraint current calculations have been changed from
average
to
maximum
to provide better
security during external faults.
where
I
restraint
= per-phase maximum of the currents after phase, ratio, and zero-sequence correction
I
differential
= per-phase vector sum of currents after phase, ratio, and zero-sequence correction
In the above equations, the 180° phase shift due to the wiring connections is taken into account, hence
the + sign to obtain the differential current.
Figure 5–7: PERCENT DIFFERENTIAL – DUAL SLOPE CHARACTERISTIC
Basic Operating Principle (3-winding):
Basic Operating Principle (2-winding):
Percent
Diff
Element
CT1
CT2
CT3
V1
V2
V3
I
1
I
2
I
3
NOTE
I
r
I
restraint
max
I
1
I
2
I
3
,
,
(
)
=
=
I
d
I
differential
I
1
I
2
I
3
+
+
=
=
%slope
I
d
I
r
----
100%
×
=
I
r
I
restraint
max
I
1
I
2
,
(
)
=
=
I
d
I
differential
I
1
I
2
+
=
=
%slope
I
d
I
r
----
100%
×
=
NOTE
100%
OPERATE
REGION
RESTRAINT
REGION
SLOPE 1
25%
SLOPE 2
100%
200%
50%
I
(x CT)
restraint
I
(x CT)
differential
15%
0.05
1.00
PICKUP 0.30
2.0
KNEEPOINT
Содержание 745 TRANSFORMER MANAGEMENT RELAY
Страница 30: ...2 8 745 Transformer Management Relay GE Power Management 2 3 SECURITY 2 GETTING STARTED 2 ...
Страница 150: ...5 100 745 Transformer Management Relay GE Power Management 5 10 INVERSE VOLTS PER HERTZ CURVES 5 SETPOINTS 5 ...
Страница 210: ...7 36 745 Transformer Management Relay GE Power Management 7 2 BLOCK DIAGRAMS 7 SCHEME LOGIC 7 ...
Страница 322: ...9 12 745 Transformer Management Relay GE Power Management 9 3 USING 745PC 9 745 PC SOFTWARE 9 ...
Страница 392: ...11 24 745 Transformer Management Relay GE Power Management 11 1 COMMISSIONING SUMMARY 11 SETPOINT TABLES 11 ...
Страница 396: ...A 4 745 Transformer Management Relay GE Power Management A 1 FIGURES AND TABLES APPENDIXA A ...
Страница 398: ...B 2 745 Transformer Management Relay GE Power Management B 1 EU DECLARATION OF CONFORMITY APPENDIXB B ...
Страница 400: ...C 2 745 Transformer Management Relay GE Power Management C 1 WARRANTY INFORMATION APPENDIXC C ...
Страница 406: ...vi 745 Transformer Management Relay GE Power Management ...
Страница 407: ...GE Power Management 745 Transformer Management Relay NOTES ...