CHAPTER 5: SETPOINTS
PROTECTION ELEMENTS
MM300 MOTOR MANAGEMENT SYSTEM – INSTRUCTION MANUAL
5–39
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
Table 5-3: NEMA curves and MM300 curve multipliers
Cooling rate
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
4.00
5.83
11.66
17.49
23.32
29.15
34.98
40.81
46.64
52.47
58.30
64.13
69.96
75.79
81.62
87.45
4.25
5.12
10.25
15.37
20.50
25.62
30.75
35.87
41.00
46.12
51.25
56.37
61.50
66.62
71.75
76.87
4.50
4.54
9.08
13.63
18.17
22.71
27.25
31.80
36.34
40.88
45.42
49.97
54.51
59.05
63.59
68.14
4.75
4.06
8.11
12.17
16.22
20.28
24.33
28.39
32.44
36.50
40.55
44.61
48.66
52.72
56.77
60.83
5.00
3.64
7.29
10.93
14.57
18.22
21.86
25.50
29.15
32.79
36.43
40.08
43.72
47.36
51.01
54.65
5.50
2.99
5.98
8.97
11.96
14.95
17.94
20.93
23.91
26.90
29.89
32.88
35.87
38.86
41.85
44.84
6.00
2.50
5.00
7.49
9.99
12.49
14.99
17.49
19.99
22.48
24.98
27.48
29.98
32.48
34.97
37.47
6.50
2.12
4.24
6.36
8.48
10.60
12.72
14.84
16.96
19.08
21.20
23.32
25.44
27.55
29.67
31.79
7.00
1.82
3.64
5.46
7.29
9.11
10.93
12.75
14.57
16.39
18.21
20.04
21.86
23.68
25.50
27.32
7.50
1.58
3.16
4.75
6.33
7.91
9.49
11.08
12.66
14.24
15.82
17.41
18.99
20.57
22.15
23.74
8.00
1.39
2.78
4.16
5.55
6.94
8.33
9.71
11.10
12.49
13.88
15.27
16.65
18.04
19.43
20.82
PICKUP
(× FLA)
STANDARD CURVE MULTIPLIERS
× 1
× 2
× 3
× 4
× 5
× 6
× 7
× 8
× 9
× 10
× 11
× 12
× 13
× 14
× 15
MM2 and MM3 curve number
1
2
3
4
5
6
7
8
MM300 curve multiplier
1
2
3
4
7
9
12
15
NEMA curve
Class 10
Class 15
Class 20
Class 30
MM300 curve multiplier
4
6
8
12
0%
25%
50%
75%
100%
0
30
60
90
120
150
180
Time (minutes)
Cool time constant = 30 minutes
63%
Thermal
capacity
used
853732A1.CDR
Summary of Contents for Multilin MM300
Page 20: ...1 14 MM300 MOTOR MANAGEMENT SYSTEM INSTRUCTION MANUAL SPECIFICATIONS CHAPTER 1 INTRODUCTION ...
Page 184: ...6 8 MM300 MOTOR MANAGEMENT SYSTEM INSTRUCTION MANUAL COMMANDS CHAPTER 6 DIAGNOSTICS ...
Page 198: ...A 6 MM300 MOTOR MANAGEMENT SYSTEM INSTRUCTION MANUAL REPAIRS CHAPTER A APPENDIX A ...
