Voltage restraint – Rockwell Automation 1407-CGCM Combination Generator Control Module User Manual
Page 168
168
Rockwell Automation Publication 1407-UM001G-EN-P - April 2013
Appendix A
Time Over-current Characteristic Curves
The CGCM unit has a maximum time dial setting of 9.9. The CGCM unit’s
equivalent time dial setting for the electromechanical maximum setting is
provided in the cross reference table even if it exceeds 9.9. This allows
interpolation as noted above.
CGCM unit time-current characteristics are determined by a linear
mathematical equation. The induction disk of an electromechanical relay has a
certain degree of non linearity due to inertial and friction effects. For this reason,
even though every effort has been made to provide characteristic curves with
minimum deviation from the published electromechanical curves, slight
deviations can exist between them.
In applications where the time coordination between curves is extremely close, we
recommend that you choose the optimal time dial setting by inspection of the
coordination study.
Voltage Restraint
In Voltage Restraint mode, when the generator voltage is between 100% and 25%
of nominal voltage, the CGCM unit automatically reduces the selected
over-current setpoint linearly according to this formula:
Adjusted over-current setpoint = original over-current setpoint * generator
voltage / voltage restraint setpoint
The range of the voltage restraint setpoint is 0…200%. A setting of zero disables
the voltage restraint.
Table 36 - Characteristic Curve Cross-reference
Curve
Equivalent To
Page
Electromechanical Relay Time Dial Setting
0.5
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
11.0
Factory Equivalent Time Dial Setting
1
ABB CO-2
169
0.3
0.8
1.7
2.4
3.4
4.2
5.0
5.8
6.7
7.7
8.6
9.7
3
ABB CO-5
171
0.4
0.8
1.5
2.3
3.3
4.2
5.0
6.0
7.0
7.8
8.8
9.9
5
ABB CO-6
173
0.5
1.1
2.0
2.9
3.7
4.5
5.0
5.9
7.2
8.0
8.9
10.1
6
ABB CO-7
174
0.4
0.8
1.7
2.5
3.3
4.3
5.3
6.1
7.0
8.0
9.0
9.8
7
ABB CO-8
175
0.3
0.7
1.5
2.3
3.2
4.0
5.0
5.8
6.8
7.6
8.7
10.0
9
ABB CO-9
177
0.3
0.7
1.4
2.1
3.0
3.9
4.8
5.7
6.7
7.8
8.7
9.6
11
ABB CO-11
179
0.3
0.7
1.5
2.4
3.2
4.2
5.0
5.7
6.6
7.8
8.5
10.3
8
GE IAC-51
176
0.6
1.0
1.9
2.7
3.7
4.8
5.7
6.8
8.0
9.3
10.6
10
GE IAC-53
178
0.4
0.8
1.6
2.4
3.4
4.3
5.1
6.3
7.2
8.4
9.6
2
GE IAC-55
170
0.2
1.0
2.0
3.1
4.0
4.9
6.1
7.2
8.1
8.9
9.8
4
GE IAC-66
172
0.4
0.9
1.8
2.7
3.9
4.9
6.3
7.2
8.5
9.7
10.9
12
GE IAC-77
180
0.5
1.0
1.9
2.7
3.5
4.3
5.2
6.2
7.4
8.2
9.9