Post on 11-Oct-2015
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Basic Electrical Terminology
AC Fundamentals
Voltage : V
Current : I Resistance: R
Power : KW
Energy : KWH Frequency - Hz
Power factorLead or Lag
AC / DC
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A.C.Fundamentals An alternating current (A.C.) is the current which
changes periodically both in magnitude & direction.
Voltages in a.c.system can be raised or lowered with
transformers. Raising of voltages in d.c.system is noteasy.
It is possible to build up high a.c.voltage, high speed
a.c.generators of large capacities. The construction
& cost of such generators are low. A.C.motors are simple in cosntruction & requires less
maintenance.
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Sine Waveform Mathematically it is very easy to write the
equations for purely sinusoidal waveform.
Any other type of waveform can be resolvedinto a series of sine & cosine waves offundamental & higher frequencies. Sum of allthese waves gives original waveform. Hencesinusoidal waveform is considered asstandard waveform.
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Sine Waveform The sine & cosine waves can pass
through linear circuits containing R,L & C
without distortion. Integration & derivative of sinusoidal
function is again a sinusoidal function.
This makes analysis of electrical circuitseasy.
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Sine Waveform
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Single Phase & Three Phase
System
Three Phase SystemAdvantages
The output of three phase machine is always greater
than single phase machine of same size by 1.5
times.
Occupies less space & less cost.
Less copper for transmission & distribution
Three phase motorsself starting
Gives steady output
Power factor is more compare to single phase
Economical
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Analogy to help understand
Electrical terms
Voltageis equiv. to the water pressure
Currentis equiv. to the Flow rate
Resistanceis like the pipe size
I = V/r
Pressure(V) Increases, Flow (I) Increases
Pipe Size Increases,r decreases & Flow(I)
increases.
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Voltage
Voltage: VVoltage is potential difference betweentwo points,
What it governs is the insulation thickness , materialto be used for particular line.
Different voltage used at different levels are generally
Residence voltageis 230 VAC, Industrial voltageis 415 VAC / 3.3 KV, 6.6 KV, 11KV Generation voltageis normally 11 KV
Transmission voltageis 400KV, 220 KV, 132KV Distribution voltagevaries from, 11 KV, 22 KV, 33 KV,66 KV, 110 KV, to 220 KV,
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Voltage levels
Voltage Levels For Motors:
LT Motors -- < 1000V
HT Motors -- > 1000V
Generally Available Voltages in India
LT220V,240V,415V,440VHT3.3KV,6.6KV,11KV
Generally Available Voltages Outside IndiaLT380V,660VHT3.0KV,6.0KV
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Current
Current: ICurrent flows through the line.
It governs
Conductor sizehigher conductor size to handle highcurrent
Conductor materialAluminum or copper conductors arecommonly used, copper handles more current,
Thumb rule is current density for aluminum is 0.8 A/ mm2and for copper it is 1.6 A/ mm2
Type of conductorstranded or solid.
Number of runsSingle run / double run / triple run etc
Higher the voltage lower is the current handling if powerremains constant. (Hence Transmission of Power is doneby Higher Voltage)
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Voltage and current parameters
R
Y
B
N
415VAC
415VAC
230VAC
Ir
Iy
Ib
In
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What is Power Factor?
To understand power factor, we will first start with the definition
of some basic terms:
KW is Working Power (also called Actual Power or Active
Power or Real Power). It is the power that actually powers the
equipment and performs useful work.
KVAR is Reactive Power. It is the power that magnetic
equipment (transformer, motor and relay) needs to produce the
magnetizing flux.
KVA is Apparent Power. It is the vectorial summation of KVARand KW.
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Power Factor
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Other way to define to Power Factor
Power factor: cos of phase angle difference betweenvoltage and current is called the power factor
Unity power factorWhen there is no phase angledifference between current and voltage
Lagging power factor- If current is lagging behindvoltage
Leading power factor- If current is leading beforevoltage
Unit p.f p.f. =cos (Lag) p.f. =cos (lead)VI V
V
I
I
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Power Factor
Unity power factor is better.
Inductance makes p.f. lagging, Inductancemeans any coil design
Capacitance make p.f. leading Industrial loads are normally inductive type,
hence p.f. is normally lagging-
Capacitors are used to improve p.f. These are
connected to the power system throughautomatic cut in/ cutoff circuit.
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Power
Power : Single phase P = V x I x cos
Three phase power P= 3 x VLx ILx cos
Where
P = Power consumption. VL = Line voltage IL = Line current. cos = Power factor
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Three Phase circuit
Star connection
VL
Vph
N
R
Y
B
VL =3 x V ph
IL = I ph
ILIph
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Three Phase circuit
Delta connection
VL
Vph
R
YB
VL = V ph
IL = 3 x I ph
IL
Iph
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Motor TerminalsStar connection
R Y B
U1 V1 W1
W2 U2 V2
Motor
T.B.
Supply Voltage
V2
W2 U2
V1
W1
U1
R
B
Y
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Motor TerminalsDelta connection
R Y B
U1 V1 W1
W2 U2 V2
Motor
T.B.
Supply Voltage
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Selection of cable size
Current flowing through the cable
Cable length
Cable typecopper or aluminum Voltage drop during motor running
shall be less than or equal to 3%
Voltage drop during motor startingshall be less than or equal to 10%
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MOTOR INTERLOCK LOGIC
STARTING INTERLOCK
Discharge Damper Closed (Fan Motors)
Discharge Valve Closed (Pump Motors)
RUNNING INTERLOCK
Deaerator Level Very Low(Pump I/L)
Drum Level Very low(Process I/L)
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(This circuit is made in MCC)
Phase Future Interlock
(Running interlock)
Stop PB
Start PB KM
Neutral
Motor contactor
coil
Basic circuit diagram of motor starter
Future Interlock
(Starting interlock or
Permissive)
KM
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These NO contacts
are used for interlocks
in MCC
Phase
Deaerator level
very low switch
This circuit is made in control Panel /PLC/DCS/SCADA
Neutral
Auxiliary
contactor
KA
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MOTOR INTERLOCK
MULTIPLE INTERLOCK SYSTEM
ID Fan
running
FD
Fan
run
ning
SA
Fan
run
ning
Drum
level
not
very
low
KA1
KA5
KA2
KA3
KA4
N
KA5KA3KA2KA1
P
KA4
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Case : Cable selection for 200
KW motor
Motor parameters are- 200 KW, 3ph,
339A,
Cable conductor- Aluminum Length of cable is 200 meters
Starter is option : DOL
Standard cable size chart
http://d/APRIL%202011%20PROGRAMMES/standard_cable_size.xlshttp://d/APRIL%202011%20PROGRAMMES/standard_cable_size.xls5/20/2018 Basics of Electricals-270213
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Motor - Selection
Following are major parameters Load GD2 Load RPM
Load MCR power consumption Test block power consumption Margin on Test block power for considering the motor
rating15% for power up to 55 KW and10% for more Standard motor rating available Look at minimumtemperature power consumption Any special accessories like VPI insulation, winding
RTD, bearing RTD, vibration sensors etc
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Motor - Selection A) DRIVEN EQUIPMENT DETAILS FOR DRIVE MOTOR SELECTION (EMS 2)
1. EQUIPMENT / APPLICATION --- FD FAN
2. MODEL --- 14144B / 1106 (TLT Engg. make)
3. METHOD OF COUPLING --- Flexible
4. RATED SPEED OF FAN --- 1480 RPM
5. GD2 AT RATED/MOTOR SPEED --- 840 kgf-m2
6. STARTING TORQUE VS. SPEED --- As enclosed
CURVE (Motor to be selected for starting with Inlet damperclosed position)
7. INSTALLATION --- Outdoor
B) DRIVE (MOTOR) DETAILS
1. MOTOR MOUNTING REQD. --- Foot (B3)
2 TYPE OF BEARINGS OF DRIVEN --- Anti friction grease lubricated
EQUIPMENT.
3. MOTOR BEARINGS --- Ball / Roller
4. DUTY CYCLE --- S1
5. SHAFT POWER AT
1) 100% MCR --- 265 kW 2) TEST BLOCK --- 334 kW @ 50 C, 374 KW @ 5 C
6. MOTOR RATING AT OPERATING --- 415 KW. CONDITION
7. CABLE SIZES FOR SIZING TERM. --- Customer to specify
BOX OF MOTORS
8. DIRECTION OF ROTATION --- Bi-directional motor
9. QUANTITY --- One
NOTE : 1) MOTOR SHALL CONFORM TO EMS1 D14-FM-CS-29480 REV. 1.
2) VENDOR SHALL SUBMIT THE MOTOR DATA SHEET & PERFORMANCE CURVES AS MENTIONED IN EMS-1.
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Motors selectionOther common
electrical parameters
Based on phases - Single phase & three phasemotors
Based on voltagesLow voltage (LT) / highvoltage (HT)
Based on working principleSquirrel cageInduction motor, Slip ring Induction motor
In Industry majority motors are Induction
motor.
Voltage, frequency, Insulation class
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MotorsImportant parameters
Enclosure /Cooling
Frame size
Duty
Fan torque speed curve
Number of starts per hour
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MOTOR PERFORMANCE
CURVES
Speed Vs Torque Curve
Thermal withstand curve
Efficiency Vs Output curve
Power factor Vs Output curve
Current Vs Starting Time / speed curve
http://d/APRIL%202011%20PROGRAMMES/motor%20curves.pdfhttp://d/APRIL%202011%20PROGRAMMES/motor%20curves.pdf5/20/2018 Basics of Electricals-270213
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MCC
MCC is a motor control center from
where individual loads can be controlled.
MCC takes one / two incoming powersupply and makes arrangement for
operating number of motors, heaters etc
with a different combination of rating.
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Electrical Components used in
MCC
Power contactors
Auxiliary contactors
Switch Fuse Unit
Air circuit Breaker
Current Transformer (CT)
Ammeter
Voltmeter
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Power Contactor
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Power Contactor
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Auxiliary (Control) Contactor
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2232
182512.518 42 to 450 Amps
2033 & 23 - 40
9.015, 14 - 23
6.010
4.57.5
3.05
23.3
1.42.3
0.91.5
0.61
0.450.75
0.30.50.20.33
22 - 32
1725
12.5- 18
8.5 - 12.5
5.5 - 8.5
4.06
3.55
2.4 - 3.6
1.8 - 2.7
1.4 - 2.1
1 - 1.5
0.67 - 1
45 - 75
30502033
66-110
Over Load relays
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Accessories
Accessories
Add - on auxiliary contact block 2 & 4 pole
Mechanical interlock (with top add-on provision)
Surge suppressor
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Electrical Components used in
MCC contd..
INCOMER BUS-BAR OUT PUT FEEDERS CABLE CHAMBER
KW / Energy meter
MCB (MINIATURE CIRCUIT BREAKER)
Panel space heater and thermostat Control transformer
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Electrical Components used in
MCC contd..
Timer
Overload relays
Push buttons Indication lamps
Selector switches ( L/R)
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Electrical Components used in
MCC contd..
Component selection based on Type 2
chart.
Fuse Protected selection Fuseless protected selection
http://d/APRIL%202011%20PROGRAMMES/Fuse_Protected.dochttp://d/APRIL%202011%20PROGRAMMES/Fuseless_Protected.dochttp://d/APRIL%202011%20PROGRAMMES/Fuseless_Protected.dochttp://d/APRIL%202011%20PROGRAMMES/Fuse_Protected.doc5/20/2018 Basics of Electricals-270213
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Electrical Components used in
MCC contd..
S.C.P.D.:Fuse / MCCB/MPCB(Isolation & Short Circuit
Protection)
Starter: contactor -Normal / overload
operations
+
Relay -Overload protectionupto locked rotor currentM
S.C.P.D.
Starter
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Electrical Components used in
MCC contd..
S.C.P.D.:Fuse / MCCB/MPCB(Isolation & Short Circuit
Protection)
Starter: contactor -Normal / overload
operations
+
Relay -Overload protectionupto locked rotor currentM
S.C.P.D.
Starter
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Type 2 Selection chart
Component selection based on Type 2
chart.
Fuse Protected selection Fuseless protected selection
http://e/Train/with%20fuse%20SG%20selection%20chart.pdfhttp://e/Train/Fuseless%20SG%20selection%20chart.pdfhttp://e/Train/Fuseless%20SG%20selection%20chart.pdfhttp://e/Train/with%20fuse%20SG%20selection%20chart.pdf5/20/2018 Basics of Electricals-270213
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Discrimination
Contactor should carry, make and break
normal and overload currents
Relay should provide protection againstsmall overloads and single phasing.
Fuse/MCCB/MPCB should provide short
circuit protection.
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Types of Co-ordination
( IS 13947 / IEC 60947 )
TYPE 1
Damage to contactor & overload relay is acceptable.No discharge beyond the enclosure is permitted.
TYPE 2No damage to overload relay or other parts isallowed. Light welding of contacts of the contactor ispermitted if they can be easily separated (e.g. by a
screw driver) without significant deformation
Di i i ti
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Discrimination
CURRENT
TIME
CONTACTOR BREAKING
CAPACITY
Relay H.R.C. Fuse
Ico
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Type 2 Co-ordination benefits
Safe and reliable performance of products
during normal and overload conditions
Proper and proven co-ordination with shortcircuit protective device
IS / IEC / EN now make verification of co-
ordination with S.C.P.D. a mandatoryrequirement
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Design parameters which
determine MCC
Rating of MCC ( Busbar rating)
Number of incomers
Number of outgoing feeders Type of feeders DOL / RDOL/ Star Delta/
Switch fuse /ACB etc.
Draw out or non draw outAmbient temp.
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Design parameters which
determine MCC contd
Temp. rise of MCC.
Operational height
Single front or double front , IPprotection
Components of MCCMicroprocessor
based relay, heavy duty relays etc
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SYMBOLS
HRC FUSE
DOL
STARTER
STARTER
STAR/DELTA
RDOLSTARTER
VOLTMETER V
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SYMBOLS
AMMETER A
CURRENTTRANSFORMER
INDICATION LAMP
SELECTORSWITCH ss
AIRCIRCUITBREAKER/MCCB
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SYMBOLSNO CONTACT
NEUTRAL LINK
OVER LOAD RELAY
NC CONTACT
CONTACTOR COIL
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SYMBOLS
DELAY)TIMER (ON
DELAY)TIMER (OFF
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MOTOR STARTERS
DOL STARTER (Direct On Line)
STAR-DELTA STARTER
AUTO TRANSFOREMR RDOL STARTER
STATOR/ ROTOR RESISTANCE
STARTER SOFT STARTER
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ELECTRICAL DRAWING
READING
Single line diagram
sld.pdf
Power and control schematic diagram for
MCC
P _C wiring.pdf
http://d/APRIL%202011%20PROGRAMMES/sld.pdfhttp://e/Train/POWER%20&%20CONTROL.pdfhttp://e/Train/POWER%20&%20CONTROL.pdfhttp://e/Train/POWER%20&%20CONTROL.pdfhttp://d/APRIL%202011%20PROGRAMMES/sld.pdf5/20/2018 Basics of Electricals-270213
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ComparisionDOL and star
Delta starter
DOL Star Delta
Starting voltage Full to the motor
phases
1/3 voltage to the motorphases
Starting current Normally 6 times the
rated current
Normally 2 times the
rated current
Starting torque Normally 2.5 times of
rated torque
Normally (2.5/3) times
the rated current
Application For lower KW rating,
Our practice is for
motor rated motorthan 37 KW.
However this is not
hard and fast rule. It
is all dependant on
power supply
system
For higher KW rating,
Our practice is for
motor rated motorthan 37 KW.
However this is not
hard and fast rule. It
is all dependant on
power supply system
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Speed Torque curve
Comparison DOL and star Delta
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VARIABLE SPEED DRIVES
Conventional method of control
Needs for drives
Types of drives DC DRIVESAC DRIVES
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DC DRIVES ADVANTAGES
HIGH STARTING TORQUE
WIDE SPEED RANGE GOOD AND PREDICTABLE CONTROLSYSTEM
VARIABLE SPEED DRIVES
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DC DRIVES DIS-ADVANTAGES
Higher Maintenance
Standard DC motor not easily available Bypass arrangement is not possible incase ofDC drive failure
VARIABLE SPEED DRIVES
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AC VARIABLE FREQUENCY
DRIVE
ADVANTAGES
SOFT STARTING OF MOTOR
STANDARD AC MOTOR CAN BE USED BYPASS ARRANGEMENT POSSIBLE POWER SAVING CAN BE USED WITH PID CONTROL LOOP
FOR PROCESS CONTROL
INCREASE IN MOTOR LIFE
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AC VARIABLE FREQUENCY
DRIVE
ADVANTAGES
DIRECTION OF MOTOR CAN BE CHANGED
NO MAINTENANCE
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Things to remember while
selecting the ACVFD drive
Current Rating of motor
Ambient temperature
IP protection of ACVFD (IP 00, IP 20, IP55)
Constant torque application or Variable
torque applicationAdditional features like Communication
with DCS (Type of protocol)
Things to remember while
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g
selecting the ACVFD drive
contd.
Number of DI / DO, AI / AO
Required protections
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BATTERY
Two different metals in certain chemical
solutions can produce electricity
Metals in cell are called electrodes Chemical solution is called electrolyte
The electrolyte reacts oppositely with
two different electrodes causing oneelectrode to lose electrons & develop
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BATTERY
positive charge & other electrode to build
up surplus of electrons & develop
negative charge The difference in potential between the
two electrode charges is cell voltage
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BATTERY
TYPES OF LEAD ACID BATTERY
SEALED MAINTENANCE FREE (SMF)
SMF VRLA TUBULAR
PLANTE
NickelCadmium (Ni-Cd)
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BATTERY
Lead Acid Battery consists of two
electrodes both made of lead sulphate
(PbSO4) Electrolytedistilled water with some
sulphuric acid
Uncharged cells does not meet anyrequirements of battery
No dissimilar metals
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BATTERY
During charging, water electrolyte breaks
down & start chemical reactions.
PbSO4 changes to spongy lead (Pb),other lead sulphate changes to lead
peroxide (PbO2)
At this, good part of water becomesH2SO4 & Battery gets charged
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BATTERY
During charging,current throbatterycauses electrolysis of water & electrolyte
changes from water to mixture of water& sulphuric acid
Water molecules breaks down in two
hydrogen (H+) ions & one oxygen (O-)
ion.
(H+) & SO4(-) produces H2SO4
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BATTERY
When battery is fully charged, electrolyte
contains high percentage of sulfuric acid
as compared to water When lead acid cell supplies current,Pb
changes to PbSO4; PbO2 changes to
lead sulphate; H2SO4 changes to H2O.
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BATTERY
During discharging, both electrodes
become lead sulphate & electrolyte
contains very less sulphuric acid.
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UPS
UPS ; Uninterrupted Power Supply
Purpose : To keep the voltage constant and tomaintain the output supply voltage even if there
is no input supply voltage Parameters for designing :
Redundant or Non redundant Static bypass required or not
Battery back up time Type of batteries (Sealed maintenance free Lead Acidetc)
Voltage, KVA rating, change over time
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Rectifier & Inverter
Rectifier : Converts AC to DC Inverter: Converts DC to AC
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Earthing
Why Earthing is important
All electrical equipment shall be double earthed
GI flats, 8 SWG wire, copper or Al. cables are used for
the earthing the equipments
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EarthingRing type
Earth
Pit
Earth
Pit
Earth Mat
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Earthing
Earth
Pit
Earth
Pit