627-500
17
INSTALLATION
Preparing for Service
Step 19
The bus construction in PMX Switchgear is
typically aluminum, as are the terminal pads
of components. Such connections employ
Belleville (formed spring-steel) washers. See
Figure 11. Check these connections, but do not
tighten factory-made connections employing
Belleville washers unless they are visibly loose;
they have been correctly torqued to 50 foot-
pounds at the factory.
NOTE:
For modules furnished with copper
bus, silver-to-silver connections are provided.
These connections employ brass fl at washers
rather than Belleville washers and should
be torqued to 35 foot-pounds since they may
have loosened during shipment. Check bus
connections and, where necessary, correctly
tighten the connecting hardware.
NOTE:
For modules employing enhanced
fuse handling construction,
do not
attempt to
remove the fuse access panel. Follow Steps 3
and 4 on page 12 to remove the rear access panel.
Also remove the hanging barrier. The main bus
can now be accessed.
For inter-module splices in the main bus
and ground bus, splice-plate kits have been
provided. These kits contain splice plates, bolts,
nuts, washers, a sheet abrasive paper, a tube of
Penetrox® A compound, and instructions. For
modules furnished with aluminum bus, both bus
ends and splice-plates have been pre-abraded
and coated with a thin layer of oxidation-
inhibiting grease at the factory.
Figure 11. Main bus with Belleville washers (if applicable).