I N S TA L L AT I O N , O P ER AT I O N S A N D M A I N T EN A N C E M A N UA L
19
High heat loss components, including certain solid
state power devices, may require removal of excess
heat to the MCC exterior environment. This is
accomplished by the utilization of exhaust fans
mounted on unit doors along with filters. These
fans and filters are factory installed.
Main incoming power cables
Refer to the motor control center drawings for the
location of the main disconnect or incoming line
terminals and the direction (top or bottom) of
cable entry. Cable-bending room provided within
the vertical section will meet or exceed National
Electrical Code requirements.Incoming line
sections are provided with cable supports.
Incoming cables must be firmly secured to
withstand the significant forces that may
be generated during a short circuit.
Cables secured at each support, as illustrated in
Figure 15B (600A example), will adequately brace
cables for faults of 100K RMS symmetrical
amperes, based on horizontal bus bracing.
However, cables should always be secured at
the first support inside the enclosure and at
the support nearest to the incoming terminals.
Insulated bushings are also recommended at
conduit terminations.
Lashing scheme for connecting cables in 2500A,
3000A, and 3200A main bus configurations. Add
5 wraps for every additional 12" of incremental
unit height.
Note:
In addition to using Type 12 exhaust
fans and filters, arc-resistant design will
also have a vented fan shield on the exterior
of the door (Figure 13C). For details on inlet
filter maintenance, see Filter Maintenance
on page 33.
—
14
—
14
Typical top entry of main
cables to the incoming-
line lug compartment
(600A shown)
—
15A
—
15B
—
15A
Typical bottom entry or
main cables to
the incoming-line
lug compartment
(600A shown)
—
15B
Cables secured at each
support (600A example),
will adequately brace
cables for faults of
100K RMS symmetrical
amperes, based on
horizontal bus bracing
5 wraps
5 wraps (x3)
10 perimeter wraps
Cable lugs
6.0"
max
5 wraps (x2)
18/24”
9”
8”
1½”
8”
18/24”
