Technical Data
Effective: May 1998 Page 25
TD.44A.01.T.E
Cutler-Hammer
Magnum DS
Metal-Enclosed
Low-Voltage Switchgear
Application
Application of Magnum DS Power Circuit Breakers
With Standard Three-Phase Transformers – Fluid Filled and Ventilated Dry Types,
Continued
Transformer Base
(100%) Rating
Secondary Short-Circuit Currents
RMS Symmetrical Amperes
Minimum Size Breakers for Selective
Trip Systems
kVA and
Percent
Impedance
Amperes➀ Maximum Short Circuit
kVA Available from
Primary System
Through
Transformer
Only
Motor
Contribution
Combined Main
Breaker
Short Delay
Trip
Feeder
Breaker
Short Delay
Trip
Feeder
Breaker
Instantaneous
Trip
Table A4 – 600 Volts Three-Phase — 100% Motor Load
500
5.0%
481 50000
100000
150000
250000
500000
Unlimited
8000
8700
9000
9300
9400
9600
1900 9900
10600
10900
11200
11300
11500
MDS-408 MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
750
5.75%
722 50000
100000
150000
250000
500000
Unlimited
10000
11100
11600
11900
12200
12600
2900 12900
14000
14500
14800
15100
15500
MDS-408
➁ MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
1000
5.75%
962 50000
100000
150000
250000
500000
Unlimited
12400
14300
15000
15600
16200
16700
3900 16300
18200
18900
19500
20100
20600
MDS-616 MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
1500
5.75%
1443 50000
100000
150000
250000
500000
Unlimited
16500
20000
21400
22700
23900
25100
5800 22300
25800
27200
28500
29700
30900
MDS-616
➁ MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
2000
5.75%
1924 50000
100000
150000
250000
500000
Unlimited
19700
24800
27200
29400
31300
33500
7700 27400
32500
34900
37100
39000
41200
MDS-620
➁ MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
MDS-408
2500
5.75%
2406 50000
100000
150000
250000
500000
Unlimited
22400
29200
32400
35600
38500
41800
9600 32000
38800
42000
45200
48100
51400
MDS-632
➁ MDS-408
MDS-408
MDS-408
MDS-608
MDS-608
MDS-608
MDS-408
MDS-408
MDS-408
MDS-608
MDS-608
MDS-608
3000
5.75%
2886 50000
100000
150000
250000
500000
Unlimited
24600
33000
37300
41500
45500
50200
11500 36100
44500
48800
53000
57000
61700
MDS-632
➁ MDS-408
MDS-608
MDS-608
MDS-608
MDS-608
MDS-608
MDS-408
MDS-608
MDS-608
MDS-608
MDS-608
MDS-608
3750
5.75%
3608 50000
100000
150000
250000
500000
Unlimited
27200
38000
43700
49800
55500
62800
14400 41600
52400
58100
64200
69900
77200
MDS-840
➁ MDS-408
MDS-608
MDS-608
MDS-608
MDS-808
MDS-808
MDS-408
MDS-608
MDS-608
MDS-608
MDS-808
MDS-808
➀ At transformer self-cooled rating.
➁ Next larger frame size main breaker may be
required for 55/65°C rise and/or forced air-
cooled (FA) transformer. Check Transformer
Secondary Ampere Rating.
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