Sometimes called "e-houses" and "electrical homes", electrical buildings are prefabricated enclosures that can be used to protect sensitive electrical or mechanical equipment. This article will cover the design and construction of electrical houses, their integration, and applications. It also includes maintenance and repair considerations.
Engineering and Design
Understanding the intended function of the equipment is the first step in designing an e-house. It could be used to provide remote power, protect VFDs or control a line of pumps. After the equipment has been defined and described, it needs to be integrated into a line.
Every e-house design is unique and will vary depending on the customer's specifications and regulatory standards. Design considerations include equipment spacing, provision, wiring and structural design.
Equipment Spacing and Provisions
NEC (National Electrical Code), spacing requirements must be met for electrical equipment installations. Space requirements are necessary to protect equipment and users from accidental energization.
For cut-outs that are to accommodate wiring, provisions must be made. The cut-out size and style of wiring will depend on whether the cable entry comes from the top or the bottom. The following are some common wire styles:
- Non-Metallic (NM), Sheathed Cable
- Underground Feeder (UF) Cable.
- THHN/THWN Wire.
Access floors allow cables to be inserted into an electrical system. It is determined by the cable entry point that determines which access floor is best.
Cables can enter from the bottom by either running underneath the structural skid, or, if space or project requirements allow, through a computer floor. A computer floor (also known as a raised floor) provides extra space for cable runs. A computer floor is a frame that has removable panels. This creates an opening for cables. There are two main types of computer floor: traditional and low profile. Low profile floors require a lower ceiling height (6 inches) and are lightweight and easy to build. It is not suitable for all applications due to its low underfloor height.
Computer floors of the past were higher than 6 inches, with an average height of 12 inches. These floors are rugged and durable, giving wires/cables plenty of space. They are however not as flexible as or as simple to use as low-profile floors. This type of floor requires the removal of access panels to manage the cables. Both types offer an efficient way to hide electrical services and allow for easy routing, but they are more expensive.
Top entry wiring allows for the passage of electrical systems through ceilings of the e-house using raceways and cable tray. Cable runs that are raceway-compliant may include conduit, tubing and other wire enclosures. Cable tray is classified as a structural support and not a raceway according to code. The cable tray support and structure must meet the requirements for strength calculations.
However, the best entry point depends on the design of your panel and how much space you have.
Programmable Logic Controllers (PLC) are industrial computers that control industrial processes and provide system control. They are responsible for electrical system operations in e-houses. They give orders and transmit information to the equipment. Through control wiring, wires are interconnected within the e-house equipment and PLC. The control wiring is the "nervous system", and receives signals through a PLC. Before construction can begin, it is necessary to determine the correct size and length of the cable. The acceptable loss, voltage, amps, and length of the cable are factors that can be used to determine the right size.
The design of an e-house depends on the customer's requirements and the project. There are many designs available: fixed, mobile, semi-mobile and onboard. The basic design of all types is the same: a frame, a skid/wheel-mounted base, walls and ceilings, as well as a door or window.
These parameters will help you design the frame for your e-house.
- The e-house is light in weight
- Wind load
- Seismic factors (earthquake situation)
- The e-house's weight and position.
- Quantity of supports available for e-house installations
These parameters are used to calculate the structural stress and deformation of the e-house frame (to which it will be subject during installation, shipment, and lifting)
A frame is only necessary for non-critical applications. The framing includes the walls for blast-resistant protection.
FAT (Factory acceptance Testing) is a method of ensuring that the system works as intended. FATs can require equipment energization, in which case additional generators are required. Additional testing may be required before shipment.
- Visual and dimensional inspection
- Electric continuity
- Insulation resistance
- Test for withstand voltage
- Routine equipment tests
- Functional tests of complete assemblies (electrical panels boards, air conditioning, etc.
Forklifts, overhead cranes or gantry cranes are used to transport the e-house to its final destination. You can also order additional equipment, such as ladders, handrails, railings and platforms separately.
Most major electrical equipment arrives pre-wired and wired at the jobsite. E-Houses require only input power and field connections. All other interconnections must be installed and tested at the site before shipment. External connections can be used with overhead and underground conduit systems.
The e-house will typically have the wiring for its power source, motor leads, and field devices installed once it reaches its destination. By placing the e-house close to the control process, cable runs can be reduced.
E-houses that are fully operational and maintained can be used for a variety of systems including the following:
- Transformer unit
- Panel unit
- IT/Operation Room
- Automation room
- Restroom (requires Air Change calculations).
- Battery room (requires Air Change calculations).
- HVAC room
- Locker room
E-houses are a solid construction option for sensitive equipment which requires protection.
Take Into Account Repair and Maintenance Considerations
It is important to maintain e-houses regularly, as minor problems can lead to serious complications. Also, it is difficult to find a technical expert immediately. These maintenance steps are highly recommended to prevent complications.
- Regular structural integrity checks are recommended. This could include checking for fastener tightness, water intrusion and floor deflection.
- Inspection of wires and all other associated electrical components
- Verify all materials for signs of degradation.
Regular maintenance can lead to operability loss, fluid leakage and material degradation. This can lead to expensive repairs. Proper e-house maintenance will ensure smooth operation for many decades.
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