Learning Journal Electrical System Design FOR HIGH-RISE Building PDF

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Learning Journal Electrical System Design FOR HIGH-RISE Building...

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ELECTRICAL SYSTEM DESIGN FOR HIGH-RISE BUILDING

Professor Roger C. Flores of Central Mindanao University's department of Electrical Engineering, which specializes in EE-86 (High Rise Building Design), discusses Electrical System Design for High Rise Building (Chapter 1 – Part 1). He will

assist the viewer in creating electrical blueprints and systems for a high-rise structure. The first chapter of the subject is system design for high-rise buildings, in which we will

explore various insights and suggestions for designing the building. He then offered several instances of high-rise buildings, including the complex building, the commercial complex building, residential condominiums, and the merging of business and

residential buildings.

He introduces the first chapter by stating that high-rise structures generally relate to

occupancy for general offices, commercial businesses, hotels/condominiums, or their mixtures. The definitions of the number of levels and areas differ from one party to the next. In terms of the electric usage equipment installed and the number of storeys,

these structures differ significantly from industrial buildings for production. Because of operating needs and limits, the latter are generally single or two-story structures. The

balleros for accumulating materials or final items are exceptions. He told us ahead of time that we would be designing a 20-story skyscraper for the video, and he emphasized the phrase silos, which are used to transport materials to a higher level and

then gravity pulls them down.

General Lighting & Power light includes general illumination, seeing tasks,

decorative features, hallways and stairways, others power for appliances and office machines, then Heating, Ventilation & Air-conditioning (HVAC) System air-conditioning for temperature control blowers and fans ventilation heaters for humidity control then

Transportation System elevators and escalators conveyors, dumbwaiters, others and Water Pumps, potable and non-potable water Intercom for the PABX telephone system

of the Communication System. In the Automatic Doors, there are access and exit points for pedestrians, garages, and freight. The Central Computer System, CPU, and peripherals Terminals for the Auxiliaries of a high-rise building intrusion and hold-up

control system, fire suppression and alarm system, background music and paging,

sound reinforcement and video facilities, and noise masking and acoustics, among others. We should keep in mind that the later components might be integrated into the

building automation system as specified in the design. These are the essential prerequisites for designing a high-rise structure.

The second topic he covered was the components of high-rise building systems.

He characterized a high-rise building electrical system as being consisting of hundreds of components that are developed and combined into a safe, effective power delivery

system. It depicts a typical building electrical system riser diagram, which demonstrates how the electrical system of the building is linked to the utility system. It is a padmounted transformer in this example, but it might be a bank of transformers located aloft

on a utility pole in other circumstances (for a demand less than 1,000 KVA).

The underground service connects the utility system to the building's main distribution panel (MDP). The main building over-current device, or main disconnect, is

located within the MDP, as are separate over-current devices for the system components that are linked to the MDP. The MDP may additionally include provisions for

utility metering as well as instruments for measuring system voltage and current. The main disconnect device can be either a circuit breaker or a fused switch. This main

device frequently has specific circuitry for monitoring low-level faults (e.g., ground faults for more than 1,000 Amp main) that would otherwise go undetected. The MDP might be regarded as the building's electrical nerve center. It is often situated near the building's

outer wall and as close to the utility transformer as feasible in order to reduce the expense of main service feeders. As a result, all system components must be carefully

selected based on design criteria and must perform safely, both under normal operating settings and during abnormal situations such as short circuits.

The following slide showed an electrical system riser diagram of a high rise building in which he eleaborated each of the electrical equipments placements such as

the main circuit breaker, over current protective system, vertical bus waj system or the bus way this is where the big copper conductors ways to its corresponding places because for a high rise building we usually use copper bass bar where it usually thick

and big wires because of the electrical load that will be used. As the video progresses, he continues to describe each component and its role in the supplied riser diagram. He

also emphasizes the need for separate power supplies for the different motor loads.

The franchise utility power business serves at a nominal level of 230/115-volt, single- or three-phase, two-, three-, or four wires depending on the kind of load and as

long as it does not exceed 1,000 KVA for the power supply system. Multiple conductors may be utilized for exceptionally high service entry current. Similarly, several

protective/disconnect devices, no more than six (6) in number, may be connected in parallel for the service entry (as stated by P.E.C.). The power company requires a load center unit sub-station for the establishment of loads bigger than 1,000 KVA, as most

commercial and industrial users do, and supplies electricity at the primary line

distribution level of 13.8 or 34.5k Volts, or whatever potential level is available in the neighborhood. The intended connected load and allowances for future expansion of the

institution determine the size of the load center; its configuration, on the other hand, is determined by the utility company's requirements and available facilities. He added that the load center's principal components are as follows: high-voltage switchgear; primary

side, power transformer section, low-voltage switchgear; secondary side metering equipment.

In large installations with private load centers, the standard practice is to utilize 208/120-volt for ordinary lighting and electricity, and 460-volt for motors. This looks to be the more cost-effective and feasible option. Three-phase electric motors are typically

dual-voltage, i.e. 460/230 volts, and employing the higher 460-volt rating results in half the ampere demand, resulting in smaller cables, a lower circuit breaker rating (despite

higher voltage), and a smaller starting unit. For lighting and appliances, a 460-volt line can also be utilized, however fixtures for such a potential may be difficult to get, such as 265-volt ballasts for fluorescent and convenience outlet with built-in unit transformers of

50 to 100 VA, 460-230/115-volt ratings.

The power supply is just 208/120 volts or 230/115 volts for total loads of 1,000 KVA or less. In some cases, and for temporary construction power, the power company

would serve 460-volt for use of construction equipment, subject to their requirements, rules, and regulations. For Load Center Configuration, if the customer enterprise is required to provide its own load center unit substation, several options are available,

again subject to the power utility company's approval.

The speaker or instructor then offered us three potential options to be used on

the following slides. He went through each slide with us so that we could fully comprehend it. He also discusses how several alternatives might aid us in our electrical design or which solution is best suited for a certain circumstance.

The power supply is just 208/120 volts or 230/115 volts for total loads of 1,000

KVA or less. In some circumstances, including for temporary construction power, the power company might provide 460-volt electricity for construction equipment usage,

according to its standards, rules, and restrictions. Any of these layouts will suit the objective of converting the utility company's incoming high-voltage line to an appropriate utilization equipment level. The ultimate decision on the desired system is usually

influenced by cost and equipment availability. Power transformers are classified as either dry or oil-immersed. The inflexibility of all of the load center arrangements

mentioned above is a common drawback. In the event that any of the primary

components, such as high or low-voltage switchgear mains, or the transformer itself, fail, the entire system will be shut down.

While a "fail-safe" system could not be implemented due to its high cost, some degree of system flexibility and dependability can be fairly achieved. The load center can be divided into two (2) equal or identical units to service the evenly divided electrical

loads, to the greatest extent possible. In the event that any of the major components of either unit fails, the remaining half remains operational: system selectivity can be

achieved, either on the primary or secondary sides, or both, by using "tie-breaker" A properly coordinated interlocking system should be provided between the tie and main breakers to prevent accidents. The load centers stated in the preceding paragraph will

be served on two (2) independent ends, resulting in the unit being referred to as "doubleended." Typically, the power provider supplies this sort of load center via two (2)

different distribution feeder lines to improve system selectivity. Figure 3.3 depicts a single-line design of a typical "double-ended" system based on Option 3. The same can be done for Option 1 and 2. One of the main points in this topic is the

mechanical/electrical interlock, which will prevent turning "ON" the tie-breaker until

either of the main breakers is turned "OFF"; metering CT's and PT's are to be installed in both high-voltage incoming lines 1 and 2.

Finally, there is an emergency power system. The power company can provide the building's power requirements at an appropriate level, continuity, and characteristics.

However, there are times when electricity may be stopped owing to a system failure or limitations, some of which are inherent in power transmission and distribution. Longer

disruptions will be extremely inconvenient for the building's residents and may even be hazardous to life and limb. Losses in terms of wasted man-hours and lost business opportunities may also be significant. A stand-by diesel engine-generator set or sets, in

addition to self-contained battery-powered emergency lighting, is offered as a solution. Because of the enormous expenses of the generator set or sets to be utilized in

relatively brief periods of main power disruptions, providing 100 percent back-up or stand-by power is not economically sensible, and is certainly bad engineering practice.

For Part 2 of Chapter 1 of the video, the same presenter from Part 1 introduced

himself again for the continuation of the subject for greater understanding and knowledge for the electrical design of a high rise structure. In the event of a power

outage, the most critical loads in the building will be supplied with emergency power. Normally, these are the following: airways and corridors lights for safety nter spaces for public transactions er pumps and fire pumps.

One or two elevators for physically disabled people, a computer system, rooms or suites for senior executives, and power transfer to a stand-by generator that can be done manually using a double-throw transfer switch or automatically using an automatic

transfer switch (ATS). For the latter, the feeder/s or line/s servicing the essential loads must not include any non-essential facilities. Separate emergency lines and panel

boards will be provided only for this reason. Picture 4.1, adapted from figure 3.3, is a common one-line diagram.

When the main power voltage drops below 70 to 80 percent of its normal level, the ATS immediately starts the generator and raises it to its rated output voltage; after 20 seconds, the ATS automatically transfers the mergency feeder mains to the generator.

When main power is restored to its rated level, the ATS immediately transfers the load back to the main power feeder; after 1 or 2 minutes of main power stable

circumstances, the generator set automatically shuts down.

The ATS could also be programmed to automatically "exercise" or operate the generator at no-load for 15-minute periods twice a week in order to keep the set and

auxiliaries in good running condition. The voltage level and time setting as mentioned may be adjusted to the desired level of the user, but instant transfer from main to standby wer is not possible because it will require time for the generator age to build-up

or uninterruptible power supply as may be required. The next paragraphs will go through it.

For the power supply for a computer system, computer hardware and operations require a regulated environment in terms of temperature, humidity, and dust for optimum performance. The same may be said for its electric power supply. Power spikes and

dips, which are common occurrences in an alternating current power supply, can occasionally exceed the computer's tolerated limitations. Some gear cannot handle

power disturbances that exceed one-fifth of a cycle of standard 60 Hz electricity. While specifically constructed automatic-voltage regulators (AVR) may fulfill the purpose, the challenge will be in the reaction time to remedy the anomalies, not to mention actual

power disruptions. When there is a power outage, the time it takes for the emergency

generator to build up and deliver power through the ATS is far longer than the computer's recovery time. As a result, the computer will shut down, needing to be reset

and restarted. If the machine is set up for long-batch runs, it may be essential to re-run the batch (i.e. program) from the beginning. There is also the possibility of mistakes and damage to computer hardware and software, which might be quite costly.

The D-C bus is supplied by the rectifier-charger, which is powered by an

emergency feeder through a "RCB" breaker. The battery is charged while also supplying power to the inverter, which converts direct current (DC) to alternating current (AC) for

the computer load. The battery's charging is properly regulated. The inverter circuit

breaker "ICB" safeguards the output feeder line to the computer. In the event of a power supply or system failure, hits and dips will not be reflected in the A-C output lines since

they are absorbed solely by the rectifier / charger; the UPS effectively filters the power to the computer. When power is lost, the floating battery will supply the D-C bus, ensuring that the inverter does not lose power; the battery bank is generally rated to

supply power for 10 to 15 minutes, which is adequate time to assemble and connect the emergency generator. The battery bank is made up of 100 to 150 industrial heavy duty

units, each with a rated terminal voltage of 2 to 2 12 Volts for larger capacity units.

When the UPS fails, the static-transfer switch "SS" will automatically transfer the

output to the by-pass line; the transfer is of the make-before-break type, so the A-C output will not detect the switch made; manual transfer to the by-pass line can also be

made via the commercial circuit breaker "CCB." There are various suppliers of imported and locally built UPS that may aid consumers in picking the configuration most suited to their unique objectives. There are several Redundancy features available to improve the

system's dependability. Another UPS system layout is a rotary type combination of an

alternating current motor-driven alternator and a stand-by diesel engine prime mover with a "flywheel," as seen in fig. This is known as a "dynamic UPS" system in some

circles. In the event of a power breakdown, the flywheel stores and supply the alternator with spinning power (i.e. kinetic energy) before the stand-by prime mover takes over the A-C motor driving operations. This is comparable to the revolving regulator method used

to keep a D-C generator running at a constant speed.

Feeder line can be bus way (bus bar trunking) or insulated conductors or a mix of both for the feeder number and sizes. The former is more adaptable and attractive, but it

is somewhat more expensive. Bus routes are quite popular, particularly for high ampere capacity lines. It can transport up to 7,000 Amps compared to wires with a maximum capacity of 540 Amps per set Bus ways, however, should not be utilized in extremely

corrosive environments such as battery rooms, in concealed areas, or where it may be susceptible to mechanical harm such as hoist ways. Only insulated conductors in sturdy

steel conduit will serve in these instances All feeder runs will end in low-voltage switchgear, which will be protected by adequately rated circuit breakers or fuses. There are no restrictions on the number of feeders, their maximum load, or the circuit

protection that goes with them. The individual's impression of flexibility, utility, and economy determines this.

The first thing to consider in Feeders and Protections is flexibility. While a single feeder may adequately serve various locations, floors, or weights, the extent of impacts situations breakdown. For a high-general rise's lighting and power system, some

examples include: Feeder 1- to service the ground level, Feeder II to serve the

basement, Feeder III to serve the 10th floor, and so on; if the floor is sufficiently vast, it may be and supplied from several feeders. The idea is to reduce the number of feeders

by using a single feeder breakdown; this principle could be applied to air conditioning. Determine the location and estimated sizes of the various electric supply equipment such as load centers, switchboards, electrical panel boards, rooms or enclosures; this

will allow the architect to allocate spaces for these equipment. After the comprehensive drawings are completed, the predicted space needs may be evaluated and altered as

needed. After consulting with the architect and lighting designer on the type of luminaires, ceiling and wall finishes, create the lighting system using either the lumens or point-by-point methodologies. The lighting design, which is largely a reflection of the

ceiling, is separated from the power layout exhibiting the floor plans for clarity. Auxiliaries may have their own sets of plans, i.e. Fire alarms, hold-up and burglar

alarms, paging and background music, noise masking, and other similar devices. Assign circuits for all lighting and power systems, including emergency lines, to suitable panels, and compute panel loads. In addition, Mr. Flores shares some of the important

takeaways that might assist us in determining various aspects in our electrical architecture utilizing these tables:...