Technical Data
Effective: May 1998
Page
34
TD.44A.01.T.E
Cutler-Hammer
Magnum DS
Metal-Enclosed
Low-Voltage Switchgear
Features – Bus
Buses and Connections — Vertical and
cross bus ratings in Magnum DS
Switchgear are based on a UL and
ANSI standard temperature rise of
65
°
C above a maximum ambient air
temperature of 40
°
C.
Bus Ampacities — Vertical and cross
bus ratings in Magnum DS are 2000,
3200, 4000, and 5000 amperes. In addi-
tion, a 6000 ampere cross bus rating
is available.
Bus Bracing — Unique vertical bus
configuration provides an optional
industry leading short circuit withstand
rating of 200,000 amperes without the
need for preceding current limiting
fuses. Standard bracing is 100,000
amperes. The “U” shaped bar is the
heart of the Magnum DS vertical bus.
This configuration provides a much
higher mechanical strength. To further
demonstrate the strength and rigidity
of this bus sustem, it has been verified
through testing to withstand 85,000
amperes short circuit for a full 60
cycles.
Silver Plating — Bolted, silver-plated
copper main buses are standard. The
plating is over the entire length of the
bar, not just at the joints. Optional tin-
plated copper buses are available.
Bus Joints — All joints are bolted and
secured with Belleville-type spring
washers for maximum joint integrity.
These washers reduce the potential of
joint hardware loosening during the
change of joint temperature associated
with variations of the loads.
Full Neutral — For 4-wire applications
the neutral bus is rated 100% of main
bus rating as standard. Half (50%) neu-
trals and neutral ratings up to a maxi-
mum of 6000 amperes are available as
an option.
Ground — A ground bus is furnished
the full length of the switchgear
assembly and is fitted with terminals
for purchaser’s connections.
Glass Reinforced Polyester and Ultra-
mid Stand-Off Insulation System —
Glass reinforced polyester has been
used on both low- and medium-volt-
age switchgear for decades. By com-
bining this industry proven material
with Ultramid insulation, a total system
providing exceptional mechanical and
dielectric withstand strength, as well as
high resistance to heat, flame, and
moisture, is produced. Substantial test-
ing to demonstrate accelerated effects
of heating and cooling on the mechani-
cal and dielectric properties of this
system prove it to provide superior
performance for decades of trouble-
free operation.
Optional Conductor Insulation
Covering — For applications requiring
additional bus protection in harsh envi-
ronments, Magnum DS Switchgear is
designed for the addition of optional
conductor insulation covering, in addi-
tion to providing full UL air clearance
without insulation. This material is
applied during the assembly of the bus
and covers all vertical and horizontal
phase bus bars. Removable boots pro-
vide access to section-to-section bus
joints for inspection and maintenance
purposes.
Optional Insulated Bus
Barriers — Optional grounded metal
barriers isolate the main bus and con-
nections from the cable compartment
providing added safety to the workers
while reducing the potential of objects
falling into the bus compartment.
Optional Bus Compartment Barriers
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