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Minimum fuse size for protection of 3-phase motors
The maximum size is determined by the requirements of the switchgear or overload relay.
The rated motor currents are for standard 1500 r.p.m. 3-phase enclosed ventilated and totally enclosed fan-cooled motors.
D.O.L. starting:
Maximum starting current 6 x rated motor current. Maximum starting time 5 s.
Y/D starting:
Maximum starting current 2 x rated motor current. Maximum starting time 15 s.
Set overload relay in the phase lead to 0.58 x rated motor current.
Rated fuse currents for Y/D starting are also valid for 3-phase motors with slip-ring motors.
For higher rated currents, starting currents and/or longer starting times, larger fuses are required.
Table is valid for "slow" and/or "gL" fuses (DIN VDE 0636).
For NH fuses with aM characteristics, fuses = rated current is selected.
500 V
Rated
motor
Motor rating
current
cos ϕ
η %
kW
A
0.06
0.7
58
0.09
0.7
60
0.12
0.7
60
0.18
0.7
62
0.25
0.7
62
0.37
0.72
66
0.55
0.75
69
0.75
0.79
74
1.1
0.81
74
1.5
0.81
74
2.2
0.81
78
3.0
0.82
80
4.0
0.82
83
5.5
0.82
86
7.5
0.82
87
11.0
0.84
87
15.0
0.84
88
18.5
0.84
88
22.0
0.84
92
30.0
0.85
92
37.0
0.86
92
45.0
0.86
93
55.0
0.86
93
75.0
0.86
94
90.0
0.86
94
110.0
0.86
94
132.0
0.87
95
160.0
0.87
95
200.0
0.87
95
250.0
0.87
95
315.0
0.87
96
400.0
0.88
96
450.0
0.88
96
500.0
0.88
97
560.0
0.88
97
630.0
0.88
97
ALL DIMENSIONS SHOWN ARE IN MILLIMETERS.
Cat. No. J09E-EN-01A
102
Low Voltage Switch Gear
600 V
Fuse
Rated
starting
motor
D.O.L.
Y/∆
current
A
A
A
0.17
2.0
-
0.25
2.0
-
0.33
2.0
-
0.48
2.0
-
0.70
2.0
-
0.90
2.0
2
1.20
4.0
2
1.50
4.0
2
2.1
6.0
4
2.9
6.0
4
4.0
10.0
4
5.3
16.0
6
6.8
16.0
10
9.0
20.0
16
12.1
25.0
16
17.4
32.0
20
23.4
50.0
25
28.9
50.0
32
33.0
63.0
32
44.0
80.0
50
54.0
100.0
63
65.0
125.0
80
79.0
160.0
80
107.0
200.0
125
129.0
200.0
160
157.0
250.0
160
114.0
184.0
250.0
200
134.0
224.0
315.0
250
162.0
279.0
400.0
315
202.0
349.0
500.0
400
253.0
436.0
630.0
500
316.0
547.0
800.0
630
396.0
615.0
800.0
630
446.0
-
-
-
491.0
-
-
-
550.0
-
-
-
618.0
In the interest of product improvement, specifications are subject to change without notice.
Appendix
Fuse
starting
D.O.L.
Y/∆
A
A
0.12
2.0
-
0.18
2.0
-
0.24
2.0
-
0.35
2.0
-
0.50
2.0
-
0.70
2.0
-
0.90
4.0
2
1.10
4.0
2
1.5
4.0
2
2.1
6.0
4
2.9
10.0
4
3.8
10.0
4
4.9
16.0
6
6.5
16.0
10
8.8
20.0
10
12.6
25.0
16
17.0
32.0
20
20.9
32.0
25
23.8
50.0
25
32.0
63.0
32
39.0
80.0
50
47.0
80.0
63
58.0
100.0
63
78.0
160.0
100
93.0
160.0
100
200.0
125
250.0
160
250.0
200
315.0
250
400.0
315
500.0
400
630.0
400
630.0
630
630.0
630
800.0
630
800.0
630
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