GE Power Management
745 Transformer Management Relay
5-95
5 SETPOINTS
5.9 TIME OVERCURRENT CURVES
5
5.9.5 IAC CURVES
The curves for the General Electric type IAC relay family are derived from the formula:
where:
T
= Operate Time (seconds)
M
= Multiplier Setpoint
I
= Input Current
I
pkp
= Pickup Current Setpoint
A
,
B
,
C
,
D
,
E
= Constants
Table 5–14: IAC CURVE CONSTANTS
IAC CURVE SHAPE
CONSTANTS
A
B
C
D
E
IAC EXTREME INVERSE
0.0040
0.6379
0.6200
1.7872
0.2461
IAC VERY INVERSE
0.0900
0.7955
0.1000
–1.2885
7.9586
IAC INVERSE
0.2078
0.8630
0.8000
–0.4180
0.1947
IAC SHORT INVERSE
0.0428
0.0609
0.6200
–0.0010
0.0221
T
M
A
B
1.03
C
–
----------------------
D
1.03
C
–
(
)
2
-----------------------------
E
1.03
C
–
(
)
3
-----------------------------
+
+
+
, for 1
I
I
pkp
---------
1.03
<
≤
×
M
A
B
I I
pkp
⁄
C
–
-------------------------
D
I I
pkp
⁄
C
–
(
)
2
---------------------------------
E
I I
pkp
⁄
C
–
(
)
3
---------------------------------
+
+
+
, for 1.03
I
I
pkp
---------
20.0
<
≤
×
M
A
B
20.0
C
–
----------------------
D
20.0
C
–
(
)
2
-----------------------------
E
20.0
C
–
(
)
3
-----------------------------
+
+
+
, for
I
I
pkp
---------
20.0
≥
×
=
Summary of Contents for 745 TRANSFORMER MANAGEMENT RELAY
Page 30: ...2 8 745 Transformer Management Relay GE Power Management 2 3 SECURITY 2 GETTING STARTED 2 ...
Page 210: ...7 36 745 Transformer Management Relay GE Power Management 7 2 BLOCK DIAGRAMS 7 SCHEME LOGIC 7 ...
Page 322: ...9 12 745 Transformer Management Relay GE Power Management 9 3 USING 745PC 9 745 PC SOFTWARE 9 ...
Page 396: ...A 4 745 Transformer Management Relay GE Power Management A 1 FIGURES AND TABLES APPENDIXA A ...
Page 400: ...C 2 745 Transformer Management Relay GE Power Management C 1 WARRANTY INFORMATION APPENDIXC C ...
Page 406: ...vi 745 Transformer Management Relay GE Power Management ...
Page 407: ...GE Power Management 745 Transformer Management Relay NOTES ...