SM-SMLSM and SML Power Fuses

SM and SML Power Fuses are especially suited for protecting cables and medium-to-large power transformers on utility, as well as industrial, commercial, and institutional power systems through 34.5 kV. They incorporate precision-engineered nondamageable silver or nickel-chrome fusible elements with time-current characteristics that are precise and permanently accurate — assuring not only dependable performance, but also continued reliability of system coordination plans.

S&C’s SM and SML Power Fuses are manufactured in accordance with a quality system certified to ISO9001:2000.

Features

With SM and SML Power Fuses, source-side devices may be set for faster operation than practical with other power fuses or circuit breakers, thereby providing better system protection without compromising coordination.

SM and SML Power Fuses are offered with maximum continuous current ratings of 200, 300, 400, and 720 amperes, in a variety of fault-interrupting ratings. They’re available in a wide variety of ampere ratings, in five different speeds: S&C “K”, Standard, Slow, Very Slow, and Coordinating. This broad selection of ampere ratings and speeds permits close fusing to achieve maximum protection and optimum coordination.

SML Power Fuses, further, include Uni-Rupter®, which provides 200-ampere single-pole live switching of single-phase and three-phase circuits on distribution systems through 25 kV. Uni-Rupter offers the ultimate in live-switching simplicity: a firm, steady opening pull on the fuse with a hookstick is all that is required for circuit interruption. Since circuit interruption is internal to Uni-Rupter, there’s no external arc or flame.

Ratings

SM Power Fuses are available in the following ratings:
Fuse Type kV Amperes, RMS, Symmetrical
Nominal Maximum BIL Maximum Interrupting
60 Hz 50 Hz
SM-20 13.8
25
34.5
17.0
27
38
95
125
150
200E or 200K
200E or 200K
200E or 200K
14 000
12 500
8 450
11 200
10 000
6 760
SM-40 4.8
13.8
25
5.5
17.0
29
60
95
150
400E
400E
400E
25 000
25 000
20 000
20 000
20 000
16 000
SM-4Z 4.8
13.8
25
34.5
5.5
17.0
27
38
60
95
150
200
200E
200E
200E
200E
17 200
12 500
9 400
6 250
13 760
10 000
7 520
5 000
SM-5S 4.8
13.8
25
34.5
5.5
17.0
27
38
60
95
150
200
400E or 720E
400E or 720E
300E
300E
27 000
25 000
20 000
17 500
27 000
25 000
20 000
17 500
SM-5SS 13.8 15.5 95 400E 34 000 25 000

 

 

SML Power Fuses are available in the following ratings:
Fuse Type kV Amperes, RMS, Symmetrical
Nominal Maximum BIL Maximum Live-Switching Interrupting Fault-Closing, Asym.
60 Hz 50 Hz One-Time Two-Time
SML-20 13.8
25
17.0
27
95
125
200E or 200K
200E or 200K
200
200
14 000
12 500
11 200
10 000
22 400
20 000
13 000
13 000
SML-40 13.8
25
17.0
27
95
125
200E
200E
200
200
12 500
9 400
10 000
7 520
20 000
15 000
13 000
13 000

Style

SM-SML-style