Power-Zone 4 Low Voltage Drawout Switchgear Structures
Introduction
Power-Zone 4 switchgear with MasterPacT circuit breakers provides the optimal switchgear solution in an industrial environment. The switchgear is designed for ease of use, system selectivity, system uptime, and low maintenance. The switchgear is easy to operate and maintain due to the technological advances in communications, power quality monitoring, and measuring capabilities.
The switchgear with drawout MasterPacT circuit breakers provide overload, short-circuit, and ground fault protection for circuits up to 635 Vac maximum. All trip unit and circuit breaker functions are operational from the front without opening the circuit breaker compartment door. MasterPacT circuit breakers carry the highest available interruption ratings without fuses, and require minimal space.
All MasterPacT circuit breakers can be equipped with MicroLogic electronic and programmable trip units to provide a choice of expanded information, power quality measurement, protection, and communication capabilities. Additionally, the optional high-end MicroLogic trip units are compatible with the optional EcoStruxure Power communications system.
The optional PowerLogic data communications system can be used in addition to MicroLogic trip units. The PowerLogic system uses highly accurate circuit monitors that work in conjunction with its system manager software to manage and control the electrical distribution system.
Power-Zone 4 switchgear is commonly found as the electrical service in the following applications:
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Airports
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Chemical refinery
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Data centers
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Oil and gas
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Heavy assembly plants
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Hospitals
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Mining
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Manufacturing
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Semi-conductor manufacturing
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University facilities
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Wastewater and water treatment facilities
Structure Design
The switchgear assembly is composed of vertical sections arranged according to customer requirements. Each section is divided into a maximum of four compartments when using MasterPacT circuit breakers, or a maximum of eight compartments when using MasterPacT MTZ1/NT circuit breakers. One or more of these compartments can be used as an auxiliary instrument compartment containing potential transformers, meters, relays, and control devices.
A horizontal secondary wireway containing the accessory terminal blocks, is directly above each circuit breaker. A spacious vertical wireway is on the right side of each circuit breaker compartment to allow wire routing through the switchgear (see Secondary Wiring System). At the top and bottom on the front of each section are horizontal wireways forming a continuous path for control (top wireway) and communications (bottom wireway) along the entire lineup.
Switchgear (Side View)
Power-Zone 4 switchgear offers compartmentalized construction. Each vertical section consists of three compartments: a front compartment (including secondary wireway), a bus compartment, and a rear cable compartment. The front compartment is divided into a maximum of four (MTZ2/NW) or eight (MTZ1/NT) compartments or auxiliary equipment. If desired, all compartments may be used for auxiliary equipment, circuit breakers, or a combination. The circuit breaker is positioned to allow ample room for control and communications wiring. Hinged doors on the auxiliary instrument compartment are available for mounting meters, relays, or other control equipment, when it does not contain a circuit breaker. A Power Quality Meter display may be mounted on the hinged door of a compartment containing a main circuit breaker.
Power-Zone 4 Switchgear Assembly
The examples below depict a typical Power-Zone 4 switchgear assembly.
Rear Cable Compartment
The rear cable compartment is located behind the bus compartment. It provides room for rear access cable installation. As standard, silver plated copper load bars extend from the load side of the circuit breaker’s stationary connecting contacts into the cable compartment. Cable terminations on the load bars permit cables to exit through either the top or bottom of the vertical sections.
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Standard Features
Available Options |
Lugs
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Mechanical cable lugs are standard for customer cable connections. Optional compression lugs (shown) are available with Power-Zone 4 switchgear. Optional cable supports (not shown) provide additional assistance in customer wiring. NOTE: Optional 45 degree lugs are available.
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Bus Compartment
The bus compartment contains the horizontal and vertical bus, and is located between the circuit breaker compartment and the cable compartment. The bus compartment is separated from the circuit breaker compartment with grounded steel barriers. The optional side and rear barriers isolate the bus compartment from the rear cable and the bus compartment in the adjacent section. In addition, service entrance barriers provide isolation around the incoming lines to meet UL and NEC requirements. Optional insulated bus helps protect the bus in harsh environments.
On four-wire systems, a neutral bus extends the length of the line-up and includes taps for the neutral cables in each vertical section. Feeder circuit breaker neutral sensors (current transformers) are provided on these taps, when ground fault protection is supplied. A removable link to the ground bus is furnished, but not connected, in the main vertical section for grounded, four-wire systems. The ground bus is a plated copper bus bar that is bolted to the rear bottom of the cable compartment and extends the entire length of the switchgear. Standard ground bus is silver plated with tin plated available as an option.
All bus joints consist of SAE Grade 5 hardware and conical spring (e.g. Belleville) washers to withstand mechanical forces exerted during short circuits. All primary bus joints consist of a minimum of 2 bolts. The ground bus contain one bolt per joint. All horizontal bus is rated to the full ampacity of the system. The vertical bus is rated to the total ampacity of the feeder circuit breakers and prepared spaces within a given vertical section per ANSI C37.20.1. As an option, vertical bus fully rated to the system ampacity can be supplied. All vertical and cross bus ratings in Power-Zone 4 switchgear are based on a standard temperature rise of 149°F (65°C) above a maximum ambient air temperature of 104°F (40°C).
Bus Compartment
 Bus Compartment (Rear View) |
Standard Features
Available Options
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 Bus Compartment (Side View) |