S&C Instruction Sheet 662-510
27
Appendix B
Table 3. Ratings and Capabilities for S&C Power Fuses with Uni-Rupter Interrupters
Fuse Type
Voltage, kV
Current, Amperes, RMS
Nom.
Max
BIL
Max
Interr.
(Sym.)
Live Switching
Load Splitting
(Parallel or Loop
Switching)
Load
Dropping
Duty-Cycle Fault-
Closing
RMS, Sym.
SML-20
14.4
17.0
95
200E or 200K
14 000
200
200
14 000
●
25
27
125
200E or 200K
12 500
200
200
12 500
■
SML-4Z
14.4
17.0
95
200E
12 500
200
200
12 500
●
25
27
125
200E
12 500
▲
200
200
12 500
■
Fault Fiter
14.4
17.0
95
200
14 000
200
200
14 000
●
25
29
125
200
12 500
200
200
12 500
■
●
Three-time duty-cycle fault-closing capability
■
Two-time duty-cycle fault-closing capability
▲
Applicable to solidly ground-neutral systems only, with fuses
connected by single-conductor, concentric-neutral-type cable to a
transformer or transformers. Rating is 9,400 amperes, RMS,
symmetrical for all other applications.
Table 2. Ratings for S&C Mini-Rupter Switches
Voltage, kV
Current, Amperes
Nom.
Max
BIL
Cont.
Live Switching
Three-Time Duty-Cycle Fault-Closing
Short-Circuit
Load-Splitting
(Parallel or
Loop Switching)
Load
Dropping
Peak
RMS, Sym.
Peak
Withstand,
Peak
One-Second
Short Time
Withstand,
RMS, Sym.
14.4
17.5
95
600
600
600
36 400
14 000
36 400
14 000
25
29
125
600
600
600
32 500
12 500
32 500
12 500
Ratings for S&C Mini-Rupter Switches
Complete ratings for Mini-Rupter Switches as applied
in S&C Manual PMH Pad-Mounted Gear are shown in
Table 2. In addition to the load-dropping ratings shown,
Mini-Rupter Switches are capable of interrupting
transformer magne tizing currents associated with
the applicable loads, as well as line-charging and
cable-cha rging cur rents ty pical for distr ibution
systems of these voltage ratings. For applications on
Ratings for S&C Power Fuses with Uni-Rupter
Interrupters
Complete ratings and capabilities of S&C Power Fuses
with Uni-Rupter Interrupters as applied in S&C Manual
PMH Pad-Mounted Gear are shown in Table 3. Uni-Rupter
Interrupters are also capable of carrying and interrupting
load currents up to and including the emergency peak-load
capabilities of the associated SML Power Fuses. In addition
to the load-dropping capabilities shown, Uni-Rupter
Interrupters are capable of interrupting transformer
magnetizing currents associated with the applicable
systems rated higher than 7.2 kV and involving load
current with high harmonic content (such as rectifier load
currents), refer to the nearest S&C Sales Office. The three-
time duty-cycle fault-closing ratings shown for Mini-Rupter
Switches define the ability to close the Mini-Rupter Switch
three times against a three-phase fault with asym metrical
current in at least one phase equal to the rated value,
with the switch remaining operable and able to carry and
interrupt rated current.
loads, as well as line-charging and cable-charging currents
typical for distribution systems of these voltage ratings.
The duty-cycle fault-closing capabil ities shown for S&C
Power Fuses with Uni-Rupter Interrupters repre sent the
fault-closing capabilities of the fuse with a Uni-Rupter
Interrupter when the fuse is closed with a purposeful
thrust without hesitation. Following the specified number
of such closings (two or three), the Uni-Rupter Interrupter
will remain opera ble and able to carry and interrupt rated
current.
