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20
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6 F 2 S 0 8 2 8
2.3 Phase Fault Overcurrent Protection
GRL150 provides three phase overcurrent protection with four independent overcurrent
thresholds OC1 to OC4. The first threshold OC1 may be set for inverse time or definite time
operation. If inverse time is selected, then any one of nine curves may be chosen, including IEC
and IEEE/ANSI standard characteristics.
OC1 has a programmable reset feature, selectable for instantaneous, definite time or dependent
time reset. This feature can be used to protect against flashing fault conditions, or to grade
correctly with electromechanical overcurrent relays.
The other overcurrent thresholds OC2 to OC4 may be set for definite time, or instantaneous
operation. These elements are immune to the effects of transformer magnetising inrush and dc
offset transient over-reach.
All elements can be inhibited by binary input signals for operation in blocked overcurrent
schemes.
2.3.1 Inverse Time (IDMT) Operation
The overcurrent protection element OC1 has the IDMT characteristics defined by equation (1):
( )
⎪⎭
⎪
⎬
⎫
⎪⎩
⎪
⎨
⎧
+
⎥
⎥
⎥
⎦
⎤
⎢
⎢
⎢
⎣
⎡
−
×
=
c
Is
I
k
TMS
t
a
1
where:
t = operating time for constant current I (seconds),
I = energising current (amps),
Is = overcurrent setting (amps),
TMS = time multiplier setting,
k, a, c = constants defining curve.
Nine curve types are available as defined in Table 2.3.1.1. They are illustrated in Figure 2.3.1.1.
Detail curves for each IDMT are shown in Appendix L.
Any one curve can selected for each IDMT element by scheme switches [M
∗∗∗
] and [M
∗∗∗
C-
∗∗
].
Table 2.3.1.1 Specification of IDMT Curves
Curve Description
Operating characteristic
Resetting characteristic
k a c kr b
IEC Normal Inverse (NI)
0.14
0.02
0
-
-
IEC Very Inverse (VI)
13.5
1
0
-
-
IEC Extremely Inverse (EI)
80
2
0
-
-
UK Long Time Inverse (LTI)
120
1
0
-
-
IEEE Moderately Inverse (MI)
0.0515
0.02
0.114
4.85
2
IEEE Very Inverse (VI)
19.61
2
0.491
21.6
2
IEEE Extremely Inverse (EI)
28.2
2
0.1217
29.1
2
US CO8 Inverse
5.95
2
0.18
5.95
2
US CO2 Short Time Inverse
0.02394
0.02
0.01694
2.261
2
Note: kr, b are used to define the reset characteristic. Refer to equation (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: ......