S&C PMH Instructions For Operation Manual page 21

SWITCHING WITH UNI-RUPTER — Continued
4. Pull the fuse vigorously through its full travel without
hesitation at any point. See Figure 20. A downward
force should be maintained on the universal pole
through the fuse-opening operation to counteract any
tendency the fuse may have to bounce toward the
closed position.
NOTE: The Uni-Rupter is designed to require a hard
pull to unlatch the fuse, thus reducing the possibility of
an incomplete opening operation.
5. Remove the Grappler from the fuse pull ring.
Ç
The fuse and fuse mounting (Uni-Rupter, load-side
hinge, and terminals) may be energized by backfeed
even when the fuse is in the fully open position. Always
assume that both terminals of a fuse are energized un-
less proved otherwise by test, by visual evidence of
open-circuit conditions on both terminals, or by ob-
serving that both terminals are grounded. Failure to
follow these precautions can result in serious
injury or death.
Figure 20. Opening the fuse.
s
S&C ELECTRIC COMPANY
DANGER
Ç
Do not close a door on a fuse in the open position. The
door will strike the fuse pull ring which will inter-
fere with door closing. The door may be closed if the
fuse is removed from its mounting.
6. Place the dual-purpose front barrier associated with
the fuse to be removed in the "slide-in" position. Use
the Grappler for this, as illustrated in Figure 21. 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
intended 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.
Figure 21. Inserting dual-purpose front barrier into the
"slide-in" position using Grappler.
INSTRUCTION SHEET
NOTICE
663-503
Page 21 of 35
August 14, 1995