Cooling Rate - GE MM300 Instruction Manual

CHAPTER 5: SETPOINTS
PICKUP STANDARD CURVE MULTIPLIERS
(× FLA)
× 1 × 2 × 3
4.00 5.83 11.66 17.49
4.25 5.12 10.25 15.37
4.50 4.54 9.08 13.63
4.75 4.06 8.11 12.17
5.00 3.64 7.29 10.93
5.50 2.99 5.98 8.97
6.00 2.50 5.00 7.49
6.50 2.12 4.24 6.36
7.00 1.82 3.64 5.46
7.50 1.58 3.16 4.75
8.00 1.39 2.78 4.16

Cooling rate

MM300 MOTOR MANAGEMENT SYSTEM – INSTRUCTION MANUAL
× 4 × 5 × 6 × 7
23.32 29.15 34.98 40.81
20.50 25.62 30.75 35.87
18.17 22.71 27.25 31.80
16.22 20.28 24.33 28.39
14.57 18.22 21.86 25.50
11.96 14.95 17.94 20.93
9.99 12.49 14.99 17.49
8.48 10.60 12.72 14.84
7.29 9.11 10.93 12.75
6.33 7.91 9.49 11.08
5.55 6.94 8.33 9.71
The following tables illustrate the relation between GE Multilin MM2 and MM3 curve
numbers, NEMA curves, and the MM300 curve multipliers.
Table 5-2: MM2 and MM3 curve numbers and MM300 curve multipliers
MM2 and MM3 curve number
MM300 curve multiplier
Table 5-3: NEMA curves and MM300 curve multipliers
NEMA curve
MM300 curve multiplier
The model causes the thermal capacity used to decrease exponentially when the steady-
state thermal capacity used value is less than the actual thermal capacity used. This
simulates motor cooling. As a stopped motor normally cools significantly slower than a
running motor, the relay has two cooling time constant setpoints, one used when the
motor is off (stopped, tripped, locked out, pre-contactor, etc.), the other used when the
motor is on (starting, running, stopping). In each case, the time constant is time in minutes
for the motor temperature to cool by 63% of the difference between the initial
temperature and ambient temperature.
Figure 5-30: Thermal model cooling following a trip at t = 0
100%
75%
50%
25%
0%
× 8 × 9 × 10 × 11
46.64 52.47 58.30 64.13
41.00 46.12 51.25 56.37
36.34 40.88 45.42 49.97
32.44 36.50 40.55 44.61
29.15 32.79 36.43 40.08
23.91 26.90 29.89 32.88
19.99 22.48 24.98 27.48
16.96 19.08 21.20 23.32
14.57 16.39 18.21 20.04
12.66 14.24 15.82 17.41
11.10 12.49 13.88 15.27
1 2 3
1 2 3
Class 10 Class 15
4 6
Cool time constant = 30 minutes
0 30 60 90
Time (minutes)
PROTECTION ELEMENTS
× 12 × 13 × 14
69.96 75.79 81.62
61.50 66.62 71.75
54.51 59.05 63.59
48.66 52.72 56.77
43.72 47.36 51.01
35.87 38.86 41.85
29.98 32.48 34.97
25.44 27.55 29.67
21.86 23.68 25.50
18.99 20.57 22.15
16.65 18.04 19.43
4 5 6 7
4 7 9 12
Class 20 Class 30
8 12
120 150 180
853732A1.CDR
× 15
87.45
76.87
68.14
60.83
54.65
44.84
37.47
31.79
27.32
23.74
20.82
8
15
5–39