CHAPTER 4: SETPOINTS
PROTECTION
869 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL
4–177
the variable must be reduced. Two types of this resetting operation are available:
“Instantaneous” and “Timed”. The “Instantaneous” selection is intended for applications
with other relays, such as most static relays, which set the energy capacity directly to zero
when the current falls below the reset threshold. The “Timed” selection can be used where
the relay must coordinate with electromechanical relays.
IEEE CURVES
The IEEE Time Overcurrent curve shapes conform to industry standards and the IEEE
C37.112-1996 curve classifications for extremely, very, and moderately inverse. The IEEE
curves are derived from the formula:
Where:
T = operate time (in seconds)
TDM = Multiplier setting
I = input current
I
pickup
= Pickup Current setting
A, B, p = constants
T
RESET
= reset time in seconds (assuming energy capacity is 100% and RESET is
“Timed”)
t
r
= characteristic constant
Table 4-25: IEEE INVERSE TIME CURVE CONSTANTS
Table 4-26: IEEE CURVE TRIP TIMES (IN SECONDS)
IEEE CURVE SHAPE
A
B
P
t
r
IEEE Extremely Inverse
28.2
0.1217
2.000
29.1
IEEE Very Inverse
19.61
0.491
2.000
21.6
IEEE Moderately Inverse
0.0515
0.1140
0.02000
4.85
MULTIPLIER
(TDM)
CURRENT (I/I
pickup
)
1.5
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
IEEE EXTREMELY INVERSE
0.5
11.341
4.761
1.823
1.001
0.648
0.464
0.355
0.285
0.237
0.203
1.0
22.682
9.522
3.647
2.002
1.297
0.927
0.709
0.569
0.474
0.407
2.0
45.363
19.043
7.293
4.003
2.593
1.855
1.418
1.139
0.948
0.813
4.0
90.727
38.087
14.587
8.007
5.187
3.710
2.837
2.277
1.897
1.626
6.0
136.090
57.130
21.880
12.010
7.780
5.564
4.255
3.416
2.845
2.439
8.0
181.454
76.174
29.174
16.014
10.374
7.419
5.674
4.555
3.794
3.252
10.0
226.817
95.217
36.467
20.017
12.967
9.274
7.092
5.693
4.742
4.065
IEEE VERY INVERSE
0.5
8.090
3.514
1.471
0.899
0.654
0.526
0.450
0.401
0.368
0.345
1.0
16.179
7.028
2.942
1.798
1.308
1.051
0.900
0.802
0.736
0.689
2.0
32.358
14.055
5.885
3.597
2.616
2.103
1.799
1.605
1.472
1.378
4.0
64.716
28.111
11.769
7.193
5.232
4.205
3.598
3.209
2.945
2.756
6.0
97.074
42.166
17.654
10.790
7.849
6.308
5.397
4.814
4.417
4.134
8.0
129.432
56.221
23.538
14.387
10.465
8.410
7.196
6.418
5.889
5.513
10.0
161.790
70.277
29.423
17.983
13.081
10.513
8.995
8.023
7.361
6.891
IEEE MODERATELY INVERSE
Summary of Contents for 869
Page 10: ...VIII 869 MOTOR PROTECTION SYSTEM INSTRUCTION MANUAL ...
Page 127: ...CHAPTER 3 INTERFACES SOFTWARE INTERFACE 869 MOTOR PROTECTION SYSTEM INSTRUCTION MANUAL 3 49 ...
Page 129: ...CHAPTER 3 INTERFACES SOFTWARE INTERFACE 869 MOTOR PROTECTION SYSTEM INSTRUCTION MANUAL 3 51 ...
Page 538: ...4 406 869 MOTOR PROTECTION SYSTEM INSTRUCTION MANUAL TESTING CHAPTER 4 SETPOINTS ...
Page 578: ...6 22 869 MOTOR PROTECTION SYSTEM INSTRUCTION MANUAL FLEXELEMENTS CHAPTER 6 METERING ...
Page 592: ...7 14 869 MOTOR PROTECTION SYSTEM INSTRUCTION MANUAL CLEAR RECORDS CHAPTER 7 RECORDS ...