Switching With Uni-Rupter; Installing And Closing The Fuse - S&C PMH Instructions For Operation Manual

S&C Source-Transfer PMH Pad-Mounted Gear
Outdoor Distribution (14.4 kv and 25 kv)

SWITCHING WITH UNI-RUPTER

Installing and Closing the Fuse

Before proceeding with the instructions on installing
d
and closing the fuse, refer to the "DANGER" on pages
4 and 5.
Ç
DANGER
When working in the high-voltage compartments,
always maintain proper clearance from energized
components. Failure to maintain proper clear-
ance will result in serious injury or death.
Always use an S&C Grappler (Catalog Number
4423) attached to a suitable universal pole (1 ¹ ⁄₄ inches
in diameter) to handle barriers and to install, remove,
open, or close fuses. The universal pole must be at
least 4 feet long (S&C Catalog Number 4451R2-E, or
equal) for 14.4-kv gear or at least 6 feet long (S&C Cata-
log Number 4452R2-E, or equal) for 25-kv gear.
Use an S&C Grappler attached to and in line with a
suitable universal pole l to perform the procedures listed
below:
1. Open the appropriate fuse-compartment door and
secure it with the door holder. See Figure 12. The adja-
cent compartment door should be closed and latched
to minimize exposure to high voltage.
2. If optional inner barrier panels (Catalog Number Suffix
"-G7") are furnished, loosen the pentahead bolts and
remove the panel.
Door holder
Figure 12. Dual-purpose front barriers for fuses in their
normal, suspended positions. Note that door holder is in
place.
663-503 INSTRUCTION SHEET
Page 16 of 35
August 14, 1995
S&C Grappler in
storage position
Storage rack for S&C
SMU-20 Fuse Units or
SM-4 Refill Units
With Micro-AT
Then remove only the dual-purpose front barrier
associated with the fuse mounting into which the fuse
is to be installed. See Figure 13. Insert the barrier into
the "slide-in" position using the Grappler as illustrated
in Figure 14. Note that the barrier is supported on the
Grappler prongs and held there by engagement of the
lifting ring with the Grappler cone.
Ç
WARNING
Do not leave dual-purpose front barriers in the "slide-in"
position for more than one week. These barriers are in-
tended for temporary use to isolate the fuse from the
contacts of the Uni-Rupter while work is being per-
formed. If the barriers are left in the "slide-in" position
for an extended period of time, there is the possibility
of corona discharge to the barriers. Prolonged expo-
sure to corona discharge can damage the barriers
and result in a flashover, injury, and equipment
damage.
d Although the operations as described in this section often refer sim-
ply to "fuses," the procedures apply to S&C Type SML-20 and SML-4Z
Power Fuses, S&C Fault Fiter Electronic Power Fuses, and current-limit-
ing fuses used in Fault Fiter Electronic Power Fuse Mountings with Uni-
Rupter.
l If the enclosure is furnished with an optional base spacer (or is
attached to a higher than normal mounting pad), it may be desirable, for
easier handling at the increased height, to reposition the Grappler on the
universal pole at a favorable angle.
Figure 13. Removing or replacing dual-purpose front
barrier with the S&C Grappler.
S&C ELECTRIC COMPANY
®
Control
s