Basic of electro mechanical arrangements for the water supply system

1. BASIC E&M ARRANGEMENTS IN WATER
AND WASTEWATER SYSTEMS

2. Preface:
The objective of this Presentation is to
understand basics on Electro-mechanical
components which are used in water supply
and wastewater systems
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3. Basic Electricity:
• CURRENT: The flow of electrons through a conductor
• Measure in Ampere
• Measured with Amp Meter
• VOLTAGE: Pressure or force that pushes current through a conductor
• Measured in volts
• Can be measured with or without current flow
• Measured with voltmeter.
• Potential difference between two points
• A battery or PV source provides a DC power source
• A rotating generator could produce AC
• Some power supplies that convert AC to DC or DC to AC
ELECTRICAL
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4. Basic Electricity:
• POWER AND POWER FACTOR
In AC circuits, the current absorbed by a load can be represented by two components:
• Active Power(KW)
• Power do the actual work in the load. Active power is measured in watts (W)
• Reactive Power(KVAR)
• The power which flows back and forth that means it moves in both directions in the
circuit, or reacts itself
• Power factor
• The ratio of active power and reactive power or Cosine angle between Voltage and
current. Represented as cosǾ
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5. Electrical Components Arrangement:
11KV HT
PANEL
LT PANEL MOTOR LOAD OTHER LOADS
APFC
PANEL
DISTRIBUTION
TRANSFORMER
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6. ELECTRICAL COMPONENTS ARRANGEMENT:
• First, we need to take a HT supply from nearest distribution sub- station
• The HT supply is step-downed using transformer
• From transformer we give connection to LT panel
• From LT panel we distribute power to different connected loads
• All components should be properly earthed for protection
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7. Types of Electrical Incoming Supply:
• HIGH TENSION SUPPLY
• Voltage range between 33 KV,11 KV,6.6 KV,3.3 KV
• Used for Large size motors Like 500 KW -2 MW
• LOW TENSION SUPPLY
• Voltage range is 415V-480V (General 3-Phase supply)
• Used for Small, Medium size motors Like 5 KW 500 KW
• Single phase supply used for 0.5 KW to 5 KW
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8. Different Type of Loads:
• Most of the electrical Loads are Inductive type of loads
• Motor Power load
• Raw power load
• Lighting load
• HVAC load
• UPS Load
• SCADA Load
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9. Load Calculation
• Load current Calculation
• Load KW P = √3 V I Cos ɸ (3ɸ) ,From this formulae we can calculate Load current
• Assume Power factor 0.8 ,Voltage 415 V
• Load Current = 100*1000/(√3*415*0.8) =173.91 A
S.No Description Load (KW) Working Standby Total (KW)
1 Pump Motor Load 30 1 1 30
2 Raw power load 20 1 0 20
3 Lighting load 10 1 0 10
4 HVAC 20 1 0 20
5 UPS 10 1 0 10
6 Scada Load 10 1 0 10
Total Load KW 100
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10. Transformer Sizing:
• The transformer sizing is depending upon connected Load(KW) and Power factor
• Calculate total connected load for different types loads like Motor Load,
Lighting Load, UPS load, SCADA load
• Transformer unit is KVA (Kilo Volt Ampere)
• Here a small calculation for transformer Sizing
Assume we have a load of 100 KW, and power factor is 0.8
The formula is
KVA=KW/Power factor
KVA=100/0.8=125
Desired transformer size is 125 KVA
*We may add 10% ~ 20 % of total load for future purpose
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11. Motors:
• In water supply systems generally, we use squirrel cage induction motor because of its constant
speed application and low maintenance
• Single phase supply and 3 Phase supply motors are used
Starting Methods Used for motors
At the time of starting motor draws 5-7 times of load current, Due to this inrush current motor
winding will damage, for preventing this we are using different type of starting methods to
reduce Motor current
*DOL starting method
*Star-delta Starting
*Variable frequency method(VFD)
*Soft starters
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12. Switch Gear and Protection:
• In an electrical network from protecting over currents, over voltages, Faults due to short circuits
we use different type of protective devices like Fuses, Circuit breakers
• Most of the electrical networks are protected by Circuit brakers because of ease of operation
• These are the different types of circuit breakers:
• MCB (Miniature Circuit Breaker) 6A-63A
• MCCB (Molded Case Circuit Breaker) 63A-800A
• VCB (Vacuum Circuit Breaker) Above 800A
• ACB (Air Circuit Breaker) Above 800A
• ELCB(Earth Leakage Circuit Breaker) < 30 mA
• Apart from this HRC(High rapturing Capacity) fuses are used for Protection for HT side
• The Ampere rating of circuit breaker is depending upon Load current
• For example, we have 100 A load current, The size of circuit breaker is 100*125% i.e., 125 A
• The 125% protection factor taken from NEC article 210.10
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13. Electrical Panel:
• The Panel is configured with MCCB’s, MCB’s and other
equipment
• Provided with provision of spare space to
accommodate possible future additional switch gear
to meet future load
• Distribute power to different Loads
• To protect and Isolate electrical system from faults
• Used friendly Operation
• It is safe and reliable
• Designed to withstand higher loads
• The Panel Configuration depends upon designed SLD
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Electrical SLD:

15. APFC(Automatic Power factor Correction Panel):
• For reduction of reactive power in connected
system
• Avoid Power Factor Surcharges & Maximum
Demand Penalties.
• It reduces the risk of Operational Issues and Power
Loss.
• Whereas it also improves the power factor
• Capacitor banks are used for improve power factor
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16. Cable:
• Different types of cable are used in electrical distribution like XLPE,
PVC,FRLS, Instrumentation cables(Copper or Aluminum)
• Armored cables are used for power distribution and for pumps
• PVC cables are used for lighting and Raw power
• PVC cables will not used in closed building because when fire
occurs it release flu gases which are harmful to humans
• Instrumentation cables are used for SCADA and PLC
• All power cables are sized based on continuous current capacity,
permissible voltage drop and short circuit current rating.
• The voltage drop shall be limited to 5 % at rated equipment current
rating
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17. Cable Laying
• Type of Cable Laying
• Under Ground Laying
• Above Ground /Conduits
• Cable trays
• Trench
• Under Ground Laying
• Armored Cable(Metal mess and Sheath) used for
under ground Laying
• Cable connected End to end through Glands for
provision of earthing
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18. Cable Laying
Cable trays
• Perforated type/Ladder type Cable trays are used Cable laying
in pump house.
• The Main Purpose of this tray is Excellent heat dispersion.
• Safe and smooth edge protects cable lines from scratch
• A Trench is Dugged in ground to laying cables
• Cable is been laid inside the trench and backfilled with soil
• Warning tape is used to avoid mechanical damages
• Separation brick should be used from cable to cable at 2
meters of distance
• Hand Holes are provided to ease of cable pulling
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19. Cable Laying
Cable Trench
• Pre-Casting trench is used for Laying
• Easy installation method
• Easy maintenance of cables
• Cable Pulling is easy
• Electrical Conduit
• Metal or PVC type conduits are used
• The conduits are not fully occupied with cables,
40% of space should be left for ventilation
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20. EARTHING SYSTEM
• The Earthing is provided to protect human from faulty
electrical system and to send unwanted current like leakage
current, short circuit current in to Earth
• The Earth Pits are designed based on Soil types
• The system is looped with GI strip to provide low resistance
and optimum earthing
• The equipment in system should be properly earthed to
reduction of electrical shock
• Pipe earthing and Plate earthing are used for system
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21. EARTHING SYSTEM
• Earthing Connections:
• For Transformer total four earth conductors are
need two for body, two for neutral and connected
through GI/Copper strip
• And every large capacity motor we need provide
earthing for Body and Neutral separately
• Generally, 25X3mm.50x6mm,75X6mm strips are
used
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22. Estimation and Costing
• From SOR( Standard of rates) we are taking desired equipment rates
S.NO DESCRIPTION AMOUNT
1 INTERNAL ELECTRIFICATION WORKS
1.1PVC CONDUIT 10,000
1.2POINT WIRING 20,000
1.3RUNS OF MAINS 25,000
1.4DISTRIBUTION BOARDS & CONTROL PANEL 50,000
1.5EARTHING 10,000
1.6FIXTURES 20,000
1.7UG CABLES 1,00,000
1.8CABLE TERMINATION 20,000
1.9RACEWAY AND TRAYS 25,000
ELECTRICAL COST 2,80,000
2 TRANSFORMER & DG SET
2.1Transformer(11kV/415V) 3,00,000
2.2DG set 1,00,000
TRANSFORMER & DG SET COST 4,00,000
TOTAL AMOUNT 6,80,000
TOTAL AMOUNT IN LAKHS 6.80
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23. THANK YOU
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