Model 6 Motor Control Centers 80459-641-01E
Section 1—About the Model 6 Motor Control Center 10/2012
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ENGLISH
Section 1—About the
Model 6 Motor Control Center
Motor control centers (MCCs) provide the most suitable method for
grouping electrical motor control and other related devices in a compact,
economical, and free-standing installation. A motor control center is made of
standardized vertical sections consisting of totally enclosed, dead front,
free-standing structures bolted together. These sections support and house
control units, a common bus bar for distributing power to the control units,
and a network of wire trough and conductor entrance areas to
accommodate outgoing load and control wires.
The control units consist of components such as combination motor
starters, branch feeder devices, and lighting panelboards. Each is mounted
in an individual, isolated compartment having its own cover. When
front-of-board unit arrangement is selected, all units are mounted on the
front side of the MCC. A 15 in. (381 mm) or 20 in. (508 mm) deep section is
provided for front-of-board mounting. The standard MCC width is 20 in.
(508 mm) with a 4 in. (102 mm) wide vertical wireway.
An optional 25 in. (635 mm) wide section with a 9 in. (229 mm) wide
wireway is also available. Larger sections are available for mounting larger
equipment. When a back-to-back arrangement is selected, the units are
mounted on both the front and rear of 31 in. (787 mm) or 41 in. (1041 mm)
deep structures. Approximately 1 in. (25 mm) of space is between
back-to-back sections. The standard height of all MCC structures is 91.5 in.
(2324 mm) without the 3 in. (76.2 mm) lifting angle.
Model 6 MCCs are available with an arc-rated option that provides an arc
containment rating tested per ANSI C37.20.7 guidelines. Additional
reinforcement and pressure relief features are added to the Model 6 MCC to
meet the arc containment rating. Refer to ANSI C37.20.7 for the specific test
requirements to which the arc-rated Model 6 MCC has been subjected.
The arc-rated Model 6 MCC can provide enhanced arc containment in case
of an arcing fault inside the MCC. This is a valuable feature along with other
arc flash enhancements available with Model 6 MCCs. Contact your local
Schneider Electric representative for more information on Model 6 MCC arc
flash options.
A Model 6 MCC with the arc-rated option includes a label (Figure 1) which
states the performance and requirements necessary to maintain the rating.
The arc containment rating is applicable to the front, sides, and rear of the
MCC (defined as Type 2 in ANSI C37.20.7).
This instruction bulletin contains specific instructions on maintaining,
modifying, and expanding an arc-rated Model 6 MCC. These instructions
must be followed to maintain the arc containment rating of the MCC. To
achieve the labeled arc containment rating, the additional "100 Millisecond,
Arc-Rated MCC, Upstream Over-Current Protection Device (OCPD)
Requirements" on Page 11 must be met.
NOTE: Application of the arc-rated option in Model 6 MCCs meeting the
requirements of IEEE C37.20.7 does not eliminate the requirements for use
of personal protection equipment (PPE).
Figure 1: Model 6 MCC 100 ms Arc-Rated
Option Label and Typical
Location on Enclosure
Arc Rating Information
This Motor Control Center has been tested and meets the requirements of
ANSI C37.20.7 to the following level:
•Type 2 accessibility
•Protection from an internal arcing event is DEVICE LIMITED
•The maximum clearing time for the protective device shall be 50 milliseconds
•Maximum short circuit current is 65,000 amperes RMS symmetrical
•Arc duration of 100 milliseconds
Attention
The above ratings apply when all the following conditions are met:
•All factory-supplied installation, operational and maintenance instructions are
followed
•Equipment shall be electrically coordinated and protected by a circuit breaker
or fuses as described in document 80459-641-01
•All units mounted in the Motor Control Center are labeled as “Arc Rated Unit”
•If spliced to another section, it must be a Model 6 Motor Control Center that
has been certified to meet the requirements of ANSI C37.20.7
•All doors are closed and all provided hardware is engaged
•All exterior covers and panels are secured using all the hardware provided
•All internal barriers are installed and secured using all the hardware provided
•Voltage does not exceed the rating indicated on the nameplate
•No modifications have been made to the factory-supplied power circuit or
unit/section structural components
•For any damage to this equipment, please contact Schneider Electric Services
to arrange for repair of the equipment
.
For further information, refer to instruction bulletin 80459-641-01.
= Arc-rated Label
= MCC Section Nameplate
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