Diseño de Sistemas Eléctricos I: Residencial y Comercial

Diseño de Sistemas Eléctricos I: Residencial y Comercial

Dr. Lionel R. Orama Exclusa, PEenero de 2006

18-Jan-2006 INEL 4407 © L.R.Orama/ A. Irizarry 2006

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Introducción al DiseñoI. ¿Qué es diseño?

A. Trabajo en equipo (arq., inci, inme, inel)B. Interesante, pero con complicaciones

1. el papel aguanta todo2. el campo no3. la sociedad tampoco

C. Limitaciones (“constraints”) que cumplirD. Certificado por Ingeniero LicenciadoE. Existen Códigos y ReglamentosF. Ética

INEL 4407 © L.R.Orama/ A. Irizarry 2006

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Puerto Rico’s Laws• Electrical Design must be certified by a

licensed engineer

• Graduate from a Credited University

• Board Exams (“reválida”) must be approved

•Fundamental, Professional

• Active Member of CIAPR

•Two years of supervised engineering

experience

• The design must comply with:• National Electrical Code (NEC)

• “Reglamento Complementario al Código

Eléctrico Nacional (AEE)”


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Proceso de DiseñoII. Proceso

A. Propuestas de diseño, arq. Solicita costos de electricidad para el proyecto

B. En general, INEL último en comenzar y terminar una vez se aprueba la propuesta

C. La AEE tiene que Endosar el proyecto1. Si la carga computada >50kVA (200A)2. Pasos para solicitar endoso

a. Estudio de campo; líneas y voltaje disponiblesb. Proyectos grandes, estudio de corto circuito

c. Punto de conexión, donde se conectaran las líneas del edificio con las de la AEE


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Electrical Design for Buildings• Electrical systems do not exist on a vacuum

– They are part of a product, a sub-system of an equipment or an structure

• In this course we will confine ourselves to design of electrical systems for buildings– Residential - small and large dwellings units, multiple

dwellings (apartments)– Commercial – general purpose units, offices, dining– Industrial – basic, light industrial facilities


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El diseño en sí

A. Computo de cargas1. Tablas para estimados (RS Means-Electrical Cost Data,

otros), para propuesta2. Por diseño, utilizando como guía el NEC

B. Circuitos ramales de iluminaciónC. Circuitos ramales de receptáculos D. Circuitos ramales para cargas de potencia

1. Acondicionadores de aire2. Elevadores y escaleras automáticas3. Otros, equipos de cocina, etc.

E. Alimentadores y paneles de distribuciónF. Subestación y bases de contadores


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National Electrical Code (NEC)• National Fire Protection Association (NFPA) &

the American National Standards Institute

(ANSI) regards the Code as purely advisory

• States make it mandatory i.e. it becomes Law

with the exceptions, provisions, clarifications

that the State decides to adopt, hence the

“Reglamento Complementario al Código

Eléctrico Nacional” in Puerto Rico

• Can be difficult to read and understand– Reading the NEC from beginning to end is worst

than reading a dictionary from beginning to end


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NEC Article 90 - Introduction

90-1 Purpose

a) Practical Safeguarding. The purpose of the

code is the practical safeguarding of persons

and property from hazards arising from the

use of electricity

b) Adequacy – compliance (with the Code) and

proper maintenance will result in an

installation free from hazard but not

necessarily efficient, convenient or adequate

for good service or future expansion of

electrical use.


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National Electrical CodeArticle 90 - Introduction

90-1 Purpose

c) Intention. This Code is not intended as a

design specification nor an instruction

manual for untrained persons.

90-2 Scope

a) Covered1. Installation of electric conductors and equipment

within or on public and private buildings or other

structures (mobile homes, recreational vehicles,

floating bldg, yards, carnivals, parking, other lots,

and industrial substations.


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90-2 Scope

b) Not Covered1. Installations in ships, watercrafts other than

floating bldg, railway rolling stock, aircraft, or

automobile vehicles other than mobile homes and

recreational vehicles.

2. Installations underground in mines

3. Installations of railways for generation,

transformation, transmission, or distribution to

operate rolling stock, signaling and

communications


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90-2 Scope

b) Not Covered

4. Installations of communication equipment under

the exclusive control of communication utilities

located outdoors or in building spaces

exclusively for such installations.

5. Installations under the exclusive control of

electric utilities for the purpose of

communications, metering, generation, control,

transformation, transmission or distribution of

electric energy.


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90-3 Code ArrangementIntroduction and nine chapters

Ch. 1-4 apply generally

Ch. 5-7 special occupancies, special equipment or

other special conditions. Ch. 1-4 apply except as

amended by Ch. 5-7 for the particular conditions.

Ch. 8 covers communications systems and it is

independent of the other chapters except where

they are specifically referenced therein.

Ch. 9 are Tables


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90-8 Wiring Planninga) Future Expansion and Convenience.

• Future expansion via ample space in raceways

• Convenience via readily accessible distribution

centers

b) Number of Circuits in Enclosures.

• The number of wires and circuits confined in a

single enclosure will be varyingly restricted.

• Limiting the number of circuits in a single

enclosure will minimize the effects from a short

circuit or ground fault in one circuit.


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Reglamento Complementario al Código Eléctrico Nacional (AEE)

• Published by the Puerto Rico Electric Power Authority (PREPA) – the authority having jurisdiction

• Defines electrical constructions in three types

1. Tipo 1 – instalaciones eléctricas interiores y exteriores2. Tipo 2 – distribución eléctrica – urbanizaciones o lotes3. Tipo 3 – extensiones de líneas eléctricas – instalaciones

de líneas para llevar facilidades eléctricas desde líneasde la AEE hasta urbanizaciones, lotes y edificios

*For every installation over 50kVA it includes substations


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Reglamento Complementario al Código Eléctrico Nacional

Seccion II Disposiciones GeneralesArtículo A. PropósitoEstablece, junto al NEC, las normas y requisitos mínimos

necesarios para garantizar la seguridad de personas y estructuras en la instalación de conductores y equipoeléctrico en Puerto Rico.


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ANSI Std Y32.9 – 1972 (1989)The standard provides a basis for1) Showing the general physical location and

arrangement of the sections of the required wiring system

2) Identifying the physical requirements for various types of materials needed to provide the electrical installation in buildings


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Drafting Graphic Symbols• Electrical layouts shall be drawn:

– to an appropriate scale or figure dimensions noted– on drawing sheets separate from the architectural

or structural drawings or the drawing sheets for mechanical or other facilities.

– Clearly. DO NOT lay out on the same drawing sheet all different electrical systems to be installed in the same building area. Use separate drawing sheets for different systems such as signal system outlets and circuits vs. lighting and power branch circuit wiring.


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Drafting Graphic Symbols

• Outlet and equipment locations with respect to the building should be shown as accurately as possible on the electrical drawing sheets to reduce reference to architectural drawings.

• All branch circuits, control circuits, and signal system circuits shall be laid out in complete detail on the electrical drawings, including identification of the number, size, and type of all conductors.


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Complete drawings of the design shall have:• Floor plan layout, to scale, of all outlet and

equipment locations and wiring runs• A complete schedule of all of the symbols used with

appropriate description of the requirements• Riser diagram showing the physical relationship of

the service, feeder and major power runs, unit substations, isolated power transformers, switchboards, panel boards, pull boxes, terminal cabinets, and other systems and equipment.


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4) Where necessary for clearness. a single line diagram showing the electrical relationship of the component items and sections of the wiring system.

5) Where necessary to provide adequate information, elevations, sections and details of equipment and special installations, anddetails of special lighting fixtures and devices

6) Sections of the building or elevation of the structure showing floor-to-floor, outlet, and equipment heights, relation to the established grade, general type of building construction, etc. Where practicable, suspended ceiling heights indicated by figure dimensions on either the electrical floor plan layout drawings or on the electrical building section or elevation drawings


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7) Where necessary to provide adequate information, plot plan to scale, showing the relation of the building or structure to other buildings or structures, service poles, service manholes, exterior area lighting, exterior wiring runs, etc

8) In the case of exterior wiring systems for street and highway lighting, area drawings showing the complete system

9) Any changes to the electrical layout should be clearly indicated on the drawings, when such changes are made after the original drawings have been completed, and should be identified on the drawing by a revision symbol


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Examples of Electrical Symbols on an Architectural Plan

Outlet (“salida”)– a point on a

wiring system where current

is taken to supply utilization

equipment

• receptacle outlet – an

outlet where one or more

receptacles are installed

single

duplex

Insulated GroundIG

receptacle outlets symbols

WPWater Proof

GFCIGround Fault Circuit

Interrupter

triplex

RRange

DClothes Dryer

F

C

Fan

Clock

Floor Outlet

Floor Single

Floor Duplex

Single

Floor Special

Purpose


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lighting outlet – an outlet

intended for the direct

connection of a lampholder,

lightning fixture, or a

pendant cord terminating in

a lampholder.

incandescent

incandescent

wall

lighting outlets symbols

X

RX

surface or

pendant exit

recessed exit

surface fluorescent surface fluorescent

wall

J junction box

X

RX

surface or

pendant exit (wall)

recessed exit (wall)

J junction box wall


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Switch symbols

cable or raceway

contains two wires

three wires on

cable or raceway

wiring concealed in

ceiling or wall

wiring concealed in

floor

wiring exposed

conduit only

Circuiting symbols

S single-pole

S2 double-pole

S3 three-way

S4 four-way

SD door

SDS dimmer

SK key

SWP water proofCO


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push button

buzzer

bell

telephone

(private system)

telephone

(outside line)

thermostat

motor

T

M

lighting panel

power panel

heating panel

transformer

television outlet

circuit breaker

overcurrent protection

device

T

TV


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System voltages

There may be several system voltages available to supply a given load but not all service voltages are available for any load.

• 3Ø service may not be available for residential loads• For 3Ø service a minimum load may be required• Minimum service voltage may be specified for large loads


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RC Secc IV. Artículo N: Clases de servicio

1. Monofásico, 120/240 V, 3 hilos. Es el servicio más común paracargas monofásicas.

120 V

120 V240 V

Voltaje primario de distribución - Al presente la AEE tiene 4 voltajes

de distribución: 4.16, 7.2, 8.32 y 13.2 kV. Las subestaciones de

distribución se conectan al sistema de transmisión a través de 38 ó

115 kV y sus capacidades varían desde 3.0 MVA hasta 50.0 MVA.

Toda subestación nueva se construye a 13.2 kV y su capacidad será

de 22.4 MVA si se conecta a voltaje 38 kV (estrella-estrella). Si la

subestación se conecta a 115 kV su capacidad podría ser de 33.6 ó

44.8 MVA (delta-estrella), según las proyecciones de carga.


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120 V

120 V240 V


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1Ø transf. connections

(a) and (b) show two

secondary coils

rated at 120 V

connected in

parallel to supply a

two-wire 120 V

circuit. No longer

used.

(c) and (d) show two

secondary coils

rated at 120 V

connected in series

to supply a three-

wire 120/240 V

circuit.

a b

c d


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RC Secc IV. Artículo N: Clases de servicio2. Trifásico, 208Y/120 V, 4 hilos. Común para cargas trifásicas

pequeñas.

120 V

208 V

primario en ∆

208 V

208 V

120 V

120 V

Sirve cargas trifásicas a 208 y cargas monofásicas a 208 y 120 V


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3Ø transformer connections – ∆Y four wire grounded secondary


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RC Secc IV. Artículo N: Clases de servicio3. Trifásico, 480Y/277 V, 4 hilos. Común para cargas trifásicas

mayores.

277 V

480 V

primario en ∆

480 V

480 V

277 V

277 V

Sirve cargas trifásicas a 480 y cargas monofásicas a 277 y 480 V


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Otros (NO en RC)Trifásico, 240 V (ó 480) V, 3 hilos.

240 V (ó 480 V)

primario en ∆

Sirve cargas trifásicas a 240 V (ó 480 V) entre las fases A, B y C

Sirve cargas monofásicas a 240 V (ó 480 V) entre dos fases

B

A

C

240 V (ó 480 V)


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RC Secc IV. Artículo B: Asuntos Generales

• Se requiere subestación (1Ø ó 3Ø) para cualquier tipo de edificio con carga calculada mayor de 50 kVA.

• Cualquier edificion con carga estimada que no exceda 75 kVA 1Ø ó 150 kVA 3Ø puede servirse de un transformadoro banco de transformadores instalado en poste de hormigón de 40 pies mínimo (o entre dos postes de hormigón de 40 pies mínimo o estructura de metal certificada para servir graveros, hormigoneras y edificios en construcción).

• En areas con problemas de espacio se permitirá, con permiso de la AEE, subestaciones 1Ø de 75 kVA en postesde la AEE si la subestación sirve más de un cliente.


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References1. NFPA 70, National Electrical Code, NFPA, 2005.2. Reglamento Complementario al Código Eléctrico Nacional,

AEE, 2000.3. ANSI Std Y32.9 – 1972 (1989) American National Standard

Graphic Symbols for Electrical Wiring and Layout Diagrams Used in Architecture and Building Construction. American National Standard Institute.

Documents

Diseño de Sistemas Eléctricos I: Residencial y Comercial