ELECTRICAL SYSTEM-BASICS

BUILDING SERVICES& SYSTEMS-II

LECTURE-2
02-10-2024
ZAIN ZULFIQAR
INTRODUCTION

• SINCE THE END OF THE NINETEENTH CENTURY

VIRTUALLY ALL BUILDINGS ARE PROVIDED WITH
ELECTRIC LIGHTINGS INSTALLATION FOR USE AT
NIGHT. WITH THE ADVENT OF FLUORESCENT LAMP
THAT IS COMPATIBLE WITH DAYLIGHT, CHEAP TO RUN
AND NOT EMITTING HEAT GAIN IN BUILDINGS, IT MADE
POSSIBLE TO INSTALL ELECTRIC LIGHTING
SUPPLEMENTING DAY LIGHT AND IN EXTREME CASES
PROVIDE THE ONLY SOURCE OF LIGHT IN A
WINDOWLESS ENVIRONMENT.
INTRODUCTION
INTRODUCTION

IN 1831 MICHAEL FARADAY SUCCEEDED IN PRODUCING

ELECTRICITY BY PLUNGING A BAR MAGNET INTO A COIL
OF WIRE. THIS IS CREDITED AS BEING THE ELEMENTARY
PROCESS BY WHICH WE PRODUCE ELECTRICITY TODAY.

THE FIRST USE OF ELECTRIC SUPPLY WERE

ESTABLISHED IN 1882 BY THOMAS EDISON,
THEREAFTER THERE HAVE BEEN CONSTANT EFFORT
THROUGHOUT THE WORLD TO SET-UP POWER STATIONS
FOR MORE THAN ONE PURPOSES.
ELECTRICITY GENERATION
ELECTRIC GENERATOR

• ELECTRICITY IS GENERATED FROM THE STORED ENERGY OF

WATER THAT MAKES TURBINE RUN AND GENERATE ELECTRICITY.

THE OTHER METHOD INCLUDES FUELS (COAL, DIESEL OR GAS) TO

FIRE BOILERS AND PASS STREAM AND GENERATE ELECTRICITY
THROUGH GENERATORS.

TRANSFORMER STEP UP SEVERAL THOUSANDS OR EVEN HUNDREDS OF

THOUSANDS OF VOLTS BEFORE IT IS SUPPLIED TO THE TRANSMISSION
LINES OR CABLE. BY TRANSMITTING ELECTRICITY AT HIGH VOLTAGES
LESS POWER IS LOST IN THE CABLES. AT THE RECEIVING END OF
VOLTAGE IS STEPPED DOWN BY TRANSFORMS IN LOCAL SUB-STATIONS
TO CONSUMERS AT 240 VOLTS.
ELECTRIC GENERATOR
SOURCES OF ELECTRICITY IN PAKISTAN
WHAT IS ELECTRICITY?

ELECTRICITY IS THE MOVEMENT OF ELECTRONS.

ELECTRONS CREATE CHARGE, WHICH WE CAN HARNESS

TO DO WORK. YOUR LIGHT BULB, YOUR STEREO, YOUR
PHONE, ETC., ARE ALL HARNESSING THE MOVEMENT OF
THE ELECTRONS IN ORDER TO DO WORK. THEY ALL
OPERATE USING THE SAME BASIC POWER SOURCE: THE
MOVEMENT OF ELECTRONS.
BASICS OF ELECTRICITY

TO UNDERSTAND THE WORLD OF ELECTRICITY AND

ELECTRONICS, IT IS VITAL TO START BY
UNDERSTANDING THE BASICS OF VOLTAGE,
CURRENT, AND RESISTANCE. THESE ARE THE THREE
BASIC BUILDING BLOCKS REQUIRED TO MANIPULATE
AND UTILIZE ELECTRICITY. AT FIRST, THESE
CONCEPTS CAN BE DIFFICULT TO UNDERSTAND
BECAUSE WE CANNOT “SEE” THEM. ONE CANNOT SEE
WITH THE NAKED EYE THE ENERGY FLOWING
THROUGH A WIRE OR THE VOLTAGE OF A BATTERY
SITTING ON A TABLE
 VOLTAGE, CURRENT, RESISTANCE

• THE THREE BASIC PRINCIPLES ARE

• VOLTAGE IS THE DIFFERENCE IN CHARGE BETWEEN TWO POINTS.

• CURRENT IS THE RATE AT WHICH CHARGE IS FLOWING.
• RESISTANCE IS A MATERIAL’S TENDENCY TO RESIST THE FLOW OF
CHARGE (CURRENT).

A CIRCUIT IS A CLOSED LOOP THAT ALLOWS CHARGE TO MOVE FROM

ONE PLACE TO ANOTHER.COMPONENTS IN THE CIRCUIT ALLOW US TO
CONTROL THIS CHARGE AND USE IT TO DO WORK.
VOLTAGE

VOLTAGE IN AN ELECTRICAL SYSTEM IS ANALOGOUS TO PRESSURE IN

A WATER SYSTEM. IT IS THE FORCE IN ELECTRICITY THAT OVERCOMES
FRICTION, AND MAKES POWER AVAILABLE OVER A LONG DISTANCE.

SO THE VOLTAGE IN THE WIRES BEHIND YOUR HOUSE MAY BE 20 TO

30 K IN VOLTAGE, BUT IT MUST BE REDUCED TO A PRESSURE THAT IS
USABLE FOR COMMERCIAL AND RESIDENTIAL DEVICES. THE STANDARD
POWER DELIVERED TO YOUR HOUSE IS PROBABLY 240 VOLTS, AND IN
SOME CASES MAY BE 208 VOLTS.
 TYPES OF CURRENT
Direct Current(DC):-
• ALTERNATING ❖In DC, the electrons flow steadily in a
CURRENT(AC):- single direction, or "forward.
❖ IN AC, ELECTRONS KEEP SWITCHING ❖Voltage of DC cannot travel very far
DIRECTIONS, SOMETIMES GOING "FORWARDS" until it begins to lose energy.
AND THEN GOING "BACKWARDS.“ ❖The frequency of direct current is
❖ SAFE TO TRANSFER OVER LONGER CITY zero.
DISTANCES AND CAN PROVIDE MORE POWER.
❖It flows in one direction in the circuit.
❖ THE FREQUENCY OF ALTERNATING CURRENT IS ❖It is the current of constant
50HZ OR 60HZ DEPENDING UPON THE
COUNTRY. magnitude.
❖ IT REVERSES ITS DIRECTION WHILE FLOWING
IN A CIRCUIT.

❖ IT IS THE CURRENT OF MAGNITUDE VARYING

WITH TIME.
ALTERNATING CURRENT

ALTERNATING CURRENT, ABBREVIATED AC, PUSHES THE

ELECTRONS BACK AND FORTH, CHANGING THE DIRECTION
OF THE FLOW SEVERAL TIMES PER SECOND. THE CURRENT
CHANGES DIRECTION AT A RATE OF 60 HERTZ, OR 60
TIMES IN ONE SECOND. THE GENERATORS USED IN POWER
PLANTS TO PRODUCE ELECTRICITY FOR YOUR HOME ARE
DESIGNED TO PRODUCE ALTERNATING CURRENT.
YOU'VE PROBABLY NEVER NOTICED THE LIGHTS IN YOUR
HOUSE ACTUALLY FLICKER AS THE CURRENT CHANGES
DIRECTION BECAUSE IT HAPPENS TOO FAST FOR OUR EYES
TO DETECT.
 ELECTRICAL POWER SYSTEM/POWER GRID

• AN ELECTRICAL POWER GRID IS AN INTERCONNECTED NETWORK

THAT DELIVERS THE GENERATED POWER TO THE CONSUMERS. IT
IS, SOMETIMES, ALSO CALLED AS AN ELECTRICAL POWER SYSTEM.
A POWER GRID CONSISTS OF GENERATING STATIONS (POWER
PLANTS), TRANSMISSION SYSTEM AND DISTRIBUTION SYSTEM.
 ELECTRICAL POWER TRANSMISSION SYSTEM

• ELECTRICAL ENERGY, AFTER BEING PRODUCED AT GENERATING STATIONS IS

TRANSMITTED TO THE CONSUMERS FOR UTILIZATION. THIS IS DUE TO THE FACT THAT
GENERATING STATIONS ARE USUALLY SITUATED AWAY FROM THE LOAD CENTERS.
 ELECTRIC POWER DISTRIBUTION SYSTEM

• ELECTRICAL POWER IS DOMINANT AS IT IS RELATIVELY MUCH EASIER TO TRANSMIT AND

DISTRIBUTE THAN OTHER FORMS OF ENERGY SUCH AS MECHANICAL.

• IMAGINE TRANSMITTING MECHANICAL ENERGY TO JUST 20 FEET OF DISTANCE. ISN'T IT

MUCH EASIER TO USE WIRES INSTEAD OF BELTS, CHAINS OR SHAFTS?
SINGLE LINE DIAGRAM OF AC POWER TRANSMISSION SYSTEM
 POWER DISTRIBUTION SYSTEM
• A DISTRIBUTION SUBSTATION IS LOCATED NEAR OR INSIDE
CITY/TOWN/VILLAGE/INDUSTRIAL AREA. IT RECEIVES POWER FROM A TRANSMISSION
NETWORK. THE HIGH VOLTAGE FROM THE TRANSMISSION LINE IS THEN STEPPED DOWN
BY A STEP-DOWN TRANSFORMER TO THE PRIMARY DISTRIBUTION LEVEL VOLTAGE.
PRIMARY DISTRIBUTION VOLTAGE IS USUALLY 11 KV, BUT CAN VARY DEPENDING
UPON REGION OR CONSUMER.
POWER DISTRIBUTION SYSTEM
A TYPICAL POWER DISTRIBUTION SYSTEM CONSISTS OF -
▪ DISTRIBUTION SUBSTATION
▪ FEEDERS
▪ DISTRIBUTION TRANSFORMERS
▪ DISTRIBUTOR CONDUCTORS
▪ SERVICE MAINS CONDUCTORS

ALONG WITH THESE, A DISTRIBUTION SYSTEM ALSO CONSISTS OF SWITCHES, PROTECTION

EQUIPMENT, MEASUREMENT EQUIPMENT ETC.
DISTRIBUTION FEEDERS
• ELECTRIC POWER LINES WHICH CONNECT SUB STATION TO DISTRIBUTORS ARE CALLED
FEEDERS.
• FEEDER FEEDS POWER FROM ONE POINT TO ANOTHER WITHOUT BEING TAPPED FROM
ANY INTERMEDIATE POINT. AS THERE IS NO TAPPING POINT IN BETWEEN, THE CURRENT
AT SENDING END IS EQUAL TO THAT OF RECEIVING-END OF THE CONDUCTOR.
 DISTRIBUTION TRANSFORMER
• A DISTRIBUTION TRANSFORMER, ALSO CALLED AS SERVICE TRANSFORMER, PROVIDES
FINAL TRANSFORMATION IN THE ELECTRIC POWER DISTRIBUTION SYSTEM. IT IS
BASICALLY A STEP-DOWN 3-PHASE TRANSFORMER. DISTRIBUTION TRANSFORMER STEPS
DOWN THE VOLTAGE TO 400V/230 VOLTS.
DISTRIBUTORS
• OUTPUT FROM A DISTRIBUTION TRANSFORMER IS CARRIED BY DISTRIBUTOR
CONDUCTOR.
• THE DISTRIBUTORS ARE TAPPED AT DIFFERENT POINTS FOR FEEDING DIFFERENT
CONSUMERS, AND HENCE THE CURRENT VARIES ALONG THEIR ENTIRE LENGTH.
• THE CURRENT THROUGH A DISTRIBUTOR IS NOT CONSTANT. SO, VOLTAGE DROP
ALONG THE LENGTH IS THE MAIN CONSIDERATION WHILE DESIGNING A DISTRIBUTOR
CONDUCTOR.
SERVICE MAINS

• A SERVICE MAINS IS A GENERALLY A SMALL CABLE WHICH CONNECTS THE

DISTRIBUTER TO THE CONSUMER ‘S METER.
 28

PRIMARY DISTRIBUTION

IT IS THAT PART OF AN AC DISTRIBUTION SYSTEM WHICH OPERATES AT

SOMEWHAT HIGHER VOLTAGES THAN GENERAL RESIDENTIAL CONSUMER
UTILIZATION.
COMMONLY USED PRIMARY DISTRIBUTION VOLTAGES IN MOST COUNTRIES ARE
11 KV, 6.6 KV AND 3.3 KV.
PRIMARY DISTRIBUTION HANDLES LARGE CONSUMERS SUCH AS FACTORIES AND
INDUSTRIES.
 29

SECONDARY DISTRIBUTION

• THIS PART DIRECTLY SUPPLIES TO THE RESIDENTIAL END CONSUMERS.

• DOMESTIC CONSUMERS ARE FED WITH SINGLE PHASE SUPPLY AT 230 VOLTS
(120 VOLTS IN USA AND SOME OTHER COUNTRIES).
• THREE PHASE SUPPLY MAY ALSO BE PROVIDED AT 400 VOLTS FOR BIG
PROPERTIES, COMMERCIAL BUILDINGS, SMALL FACTORIES ETC
SMART GRID

• THE SMART GRID IS THE MODERNIZATION OF THE ELECTRICITY DELIVERY

SYSTEM. A SMART GRID DIFFERS FROM THE TRADITIONAL GRID IN THAT IT
ALLOWS TWO-WAY COMMUNICATION OF ELECTRICITY DATA, RATHER THAN A
ONE WAY FLOW. SMART GRIDS ENABLE REAL TIME DATA COLLECTION
CONCERNING ELECTRICITY SUPPLY AND DEMAND DURING THE TRANSMISSION
AND DISTRIBUTION PROCESS, MAKING MONITORING, GENERATION,
CONSUMPTION AND MAINTENANCE MORE EFFICIENT.
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THANK YOU