150-454-111-06
Appendix B - Technical Reference
HRE-454
February 25, 2000
25
HRE-454 E
NCLOSURE
I
NFORMATION
All HRE-454 units have access to an order wire pair shown in
and
enclosure mounting plate allows the unit to be tilted 31° from its vertical position (see
). This
reduces the headroom required in manhole installations from10 inches to 3 inches and the amount of valuable air
space required for such underground applications.
To pivot the enclosure out from its vertical position, perform the following steps:
1
Loosen the four bolts that connect the pivot bracket to the enclosure baseplate and loosen the housing up
slightly.
2
Pull the housing out until the top two pivot bracket bolts rest against the end of the two pivot bracket slots.
Stainless Steel Dome
A stainless steel dome cover fits over the card cage and protects the enclosure from heat and other harmful
environmental effects. The dome seals the inner assembly when clamped to the baseplate, providing a seamless,
corrosion-resistant, easily-removed protective cover. The stainless steel cover V-retainer, equipped with a T-bolt,
is used to tighten the dome firmly against the O-ring on the baseplate. The purpose of the O-ring is to create a
pressure-tight seal between the dome and the baseplate. There is also a locking cover over the T-handle which
prevents unauthorized access to the enclosure. This cover accepts a padlock with a maximum shackle diameter of
0.3-inch (0.76 cm). The V-retainer T-bolt should be torqued between 10 and 15 inch-pounds for proper sealing.
Card Cage
The card cage (
) inside the enclosure has four mounting positions which hold up to four
doubler or remote units. There is also a retainer bar on top of the card cage that extends the width of the cage. The
retainer bar is used for:
•
Writing down the circuit ID number on the label attached to the bar.
•
Preventing the doubler or remote units from disconnecting when the enclosure is subjected to severe
vibrations or mounted in non-vertical planes.
•
Accessing the doubler or remote units by loosening the side wingnuts and rotating the retainer bar forward.
The enclosure has a mechanism that enables the card cage to tilt up approximately 45°. This provides easy access
to the rear of the card cage for servicing the Line Protection Unit (LPU) board. Two knobbed retainer screws at
the base of the card cage (one on each side) lock the card cage in its normal level position. This helps prevent it
from tilting during severe vibrations. The cable stubs shield is grounded through a braided shield ground wire
which is connected to the card cage base (see
for wire location). The card cage itself is grounded through
a ribbon ground connected between the card cage base and the side.
