Download  Print this page

GE UR Series Instruction Manual Page 278

Line differential relay.
Hide thumbs
   
1
2
3
4
Table of Contents
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470

Advertisement

8.1 OVERVIEW
The sum of the first and the third term of the severity equation is analogous to the operate quantity of a conventional
approach, and the last term is analogous to the restraint quantity of a conventional approach. The second term arises from
the orientation of the ellipse. The equation yields an adaptive elliptical restraint characteristic. The size, shape, and orienta-
tion of the ellipse adapt to power system conditions. The computed severity is zero when the operate phasor is on the ellip-
tical boundary, is negative inside the boundary, and positive outside the boundary. Outside of the restraint boundary, the
computed severity grows as the square of the fault current. The restraint area grows as the square of the error in the mea-
surements.
It is interesting to compare the severity equation with conventional approaches that are based on operate and restraint
terms. For example, one typical operating characteristic based on restraint and operating quantities is shown in Figure 8–1.
The restraint current in the conventional approach is derived from the sum of the magnitudes of the terminal currents, and
is analogous to the last term in the elliptical severity equation. The operating current for the conventional scheme is derived
from the sum of the currents, and is analogous to the first and third term of the elliptical severity equation.
Another way of plotting the conventional restraint curve as a region in the complex plane is shown in Figure 8–2. The
restraint region is the area inside the circle. Whenever the sum of the current phasors falls within the circle, the conven-
tional approach is restrained. The diameter of the circle depends on the restraint current.
8
Figure 8–2: CONVENTIONAL RESTRAINT CHARACTERISTIC IN TERMS OF PHASORS
The adaptive elliptical restraint has several advantages over the conventional approach. Although both the adaptive
approach and the conventional approach have a restraint region that changes size, the adaptive elliptical restraint region
more accurately reflects the sources of measurement error. For example, the conventional approach does not take into
account the effects of traveling waves and switching surges on the accuracy of measurements. The adaptive elliptical
restraint region provides the best statistical confidence and is more sensitive and more secure than the conventional
approach.
8-4
Operating Zone
Restraint Current
Figure 8–1: CONVENTIONAL RESTRAINT CHARACTERISTIC
L90 Line Differential Relay
Imaginary
current
Real current
8 THEORY OF OPERATION
GE Power Management

Advertisement

Table of Contents

   Also See for GE UR Series

   Related Manuals for GE UR Series

This manual is also suitable for:

L90

Comments to this Manuals

Symbols: 0
Latest comments: