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6 F 2 S 0 8 2 8
Ln
= natural logarithm
Figure 2.7.1.1 illustrates the IEC60255-8 curves for a range of time constant settings. The
left-hand chart shows the ‘cold’ condition where an overload has been switched onto a previously
un-loaded system. The right-hand chart shows the ‘hot’ condition where an overload is switched
onto a system that has previously been loaded to 90% of its capacity.
Thermal Curves (Cold Curve -
no prior load)
0.01
0.1
1
10
100
1000
1
10
Overload Current (Multiple of I
AOL
)
O
p
erate Time (minutes)
Thermal Curves (Hot Curve -
90% prior load)
0.001
0.01
0.1
1
10
100
1000
1
10
Overload Current (Multiple of
I
AOL
)
O
p
erate Ti
me (mi
nutes)
Figure 2.7.1.1 Thermal Curves
2.7.1 Scheme
Logic
Figure 2.7.1.2 shows the scheme logic of the thermal overload protection.
The thermal overload element THM has independent thresholds for alarm and trip, and outputs
alarm signal THM ALARM and trip signal THM TRIP. The alarming threshold level is set as a
percentage of the tripping threshold.
The alarming and tripping can be disabled by the scheme switches [THMAL] and [THMT]
respectively or binary input signals THMA BLOCK and THM BLOCK.
τ
100
50
20
10
5
2
1
τ
100
50
20
10
5
2
1
Содержание GRL150-100 Series
Страница 149: ... 148 6 F 2 S 0 8 2 8 ...
Страница 150: ... 149 6 F 2 S 0 8 2 8 Appendix A Programmable Reset Characteristics and Implementation of Thermal Model to IEC60255 8 ...
Страница 154: ... 153 6 F 2 S 0 8 2 8 Appendix B Signal List ...
Страница 180: ... 179 6 F 2 S 0 8 2 8 Appendix C Binary Output Default Setting List ...
Страница 182: ... 181 6 F 2 S 0 8 2 8 Appendix D Details of Relay Menu ...
Страница 195: ... 194 6 F 2 S 0 8 2 8 ...
Страница 196: ... 195 6 F 2 S 0 8 2 8 Appendix E Case Outline ...
Страница 199: ... 198 6 F 2 S 0 8 2 8 ...
Страница 200: ... 199 6 F 2 S 0 8 2 8 Appendix F Typical External Connections ...
Страница 223: ... 222 6 F 2 S 0 8 2 8 ...
Страница 228: ... 227 6 F 2 S 0 8 2 8 Appendix I Return Repair Form ...
Страница 232: ... 231 6 F 2 S 0 8 2 8 Appendix J Technical Data ...
Страница 238: ... 237 6 F 2 S 0 8 2 8 Appendix K Symbols Used in Scheme Logic ...
Страница 241: ... 240 6 F 2 S 0 8 2 8 ...
Страница 242: ... 241 6 F 2 S 0 8 2 8 Appendix L Inverse Time Characteristics ...
Страница 248: ... 247 6 F 2 S 0 8 2 8 Appendix M IEC60870 5 103 Interoperability ...
Страница 260: ... 259 6 F 2 S 0 8 2 8 Appendix N Resistor Box Option ...
Страница 263: ... 262 6 F 2 S 0 8 2 8 ...
Страница 264: ... 263 6 F 2 S 0 8 2 8 Appendix O Ordering ...
Страница 267: ......