GE MM3, Instruction Manual, Page: 92 / 230

5–12 MM3 MOTOR MANAGER 3 – INSTRUCTION MANUAL
S2 PROTECTION CHAPTER 5: SETPOINTS
For example, given the following motor information: motor full load current (FLC) = 100 A,
actual motor current = 80 A, LRT Hot = 7 seconds, and LRT Cold = 10 seconds, the thermal
capacity used can be determined from the
HOT/COLD CURVE RATIO
as follows:
(EQ 5.1)
Therefore:
(EQ 5.2)
The trip time for the standard GE Multilin overcurrent curves are shown below.
K+E 11” × 17” format for the GE Multilin standard time overcurrent curves are available
from factory upon request.
Table 5–1: Standard Overload Curve Trip Times (in Seconds)
Overload
level
Curve number
1 2 3 4 5 6 7 8
1.05 7200 7200 7200 7200 7200 7682 10243 12804
1.10 416 833 1250 1666 2916 3750 5000 6250
1.20 198 397 596 795 1392 1789 2386 2982
1.30 126 253 380 507 887 1141 1521 1902
1.40 91 182 273 364 638 820 1093 1367
1.50 70 140 210 280 490 630 840 1050
1.75 42 84 127 169 297 381 509 636
2.00 29 58 87 116 204 262 350 437
2.25 21 43 64 86 150 193 258 323
2.50 16 33 50 66 116 150 200 250
2.75 13 26 39 53 93 119 159 199
3.00 10 21 32 43 76 98 131 164
3.50 7.8 15 23 31 54 69 93 116
4.00 5.8 11 17 23 40 52 69 87
4.50 4.5 9 13 18 31 40 54 68
5.00 3.6 7.2 10 14 25 32 43 54
5.50 3 6 9 12 20 26 35 44
6.00 2.5 5 7.5 10 17 22 30 37
6.50 2.1 4.2 6.3 8.4 14 19 25 31
7.00 1.8 3.6 5.4 7.2 12 16 21 27
7.50 1.6 3.2 4.8 6.4 11 14 19 23
8.00 1.4 2.8 4.2 5.6 9.8 12 16 20
HOT/COLD CURVE RATIO
LRT Hot
LRT Cold
---------------------
100
×
7 sec.
10 sec.
-----------------
100
×
70%
= = =
hermal capacity used
actual motor current
FULL LOAD CURRENT
-----------------------------------------------------
100% HOT/COLD CURVE RATIO
–
( ×
=
80 A
100 A
--------------
100% 70%
–
( ) ×
=
24%
=
NOTE