INTERNSHIP REPORTAT ELECTRICAL AND MECHANICAL DEPARTMENT OF

POWER TRANSMISSION AND DISTRIBUTION IC

LARSEN & TOUBRO LIMITED

SUBMITTED BY

B.SINDHUJA

M.G.VISHALI

Electrical and Electronics Engineering

RMD Engineering College

During the period09-06-2014 to 20-06-2014

CONTENTS

Acknowledgement

Introduction – BMRCL Project

BMRCL Specifications

Electrification of metro rail stations

Earthing philosophy

Assignment- vendor offer review report

Diesel Generator sizing

Load details and Switchgear sizing

L.V Feeder cable sizing

Distribution Transformer sizing

Electrical calculations -Lighting calculations

Cable schedule

ACKNOWLEDGEMENT

The industrial exposure that we have experienced as trainees in

Industrial Electrification Business Unit of Power transmission and

Distribution Independent Company (PT&D IC) of L&T Construction

has helped us a lot not only in improving our theoretical knowledge but

also to understand the working of a large industry and Practical

engineering.

We are sincerely grateful to the management of PT & D IC and

Mr. D. Maheswaran, GM & Head Engineering (IE&SS)- PT&D IC, for

giving us an opportunity to undergo a ten days Internship program in

their organization.

We would like to express our deepest gratitude towards Mr. Krishnan

C. Menon for associating us in this training. We also express our sincere

gratitude & thanks to Ms. Priyanka Dharamshi and Mrs. R.Sandhiya

for the guidance and encouragement at various stages during our

internship.

Last but not the least; we would like to thank L&T Construction for

providing us this opportunity and exposure to the real Industry.

BANGALORE METRO RAIL PROJECT

What is METRO Rail?

• An urban electric passenger transport system

• High capacity & high frequency of service

• Totally independent from other traffic road or pedestrianRevolution in traction systems

Electric trains came to existence with DC over headlines of 1.5kV & 3kV DC in late 19th Century.

Usage of high voltage DC would lead to electrocution and considered unsafe. Hence was restricted to low speed to overcome the same

AC traction system came to existence in mid 20th century with 15kV system feeding the DC Series motors through AC-DC rectifiers.

Due to the technical difficulty in rectifier technology 25kV AC Induction motor traction system came to existence in late 20th century.

There was revolution in DC traction system as it was more appealing for metro due to its aesthetic aspects. Due to high demand of Metro 750V DC Third rail traction system came to existence. “Third rail” Terms the rail other than two running rails which feeds power to the traction motors

Advantages & Disadvantages of 25kV over 750V DC Traction system

• 25kV AC Traction system is safer. • Used for high speed trains for longer distances• Cost effective compared to DC third rail• But causes imbalance in 3-phase supply

Delhi Metro

(Line -1, Line 2, Line 3, Line

4, Line 5 & Line 6)

Kolkata Metro(Line -1)

Bangalore Metro(Reach-1, Reach- 2,

Reach – 3 & Reach -4)

Jaipur Metro

Chennai Metro

Hyderabad Metro

Total No. of Stations

142 24 42 11 40 64

Line Length 189 kms 28kms 42 kms 9.25 kms 42 kms 72 kms

Traction System 25 kV AC 750 VDC 750 VDC 25 kV AC 25 kV AC 25 kV AC

Type of Station

Both U/G & Elevated

Both U/G & Elevated

Both U/G & Elevated

Both U/G &

Elevated

Both U/G &

ElevatedElevated

Project Status Completed** Completed Completed** Under

ExecutionUnder

ExecutionUnder

Execution

Comparison between various metro rails in India

** These projects are executed in different phases and some phases are handed over and are under commercial operation.

Characteristics of railway electrification

Two forms in which Power is supplied to moving trains:

1. Overhead line or catenary wire suspended from poles or towers along the track or from structure or tunnel ceilings

2. Third rail mounted at track level and contacted by a sliding "pickup shoe“ usually use the running rails as the return conductor but some systems use a separate fourth rail for this purpose.

Third rail : A third rail is a method of providing Electric power to a railway train, through a semi-continuous rigid conductor placed alongside or between the rails of a railway track.

The conductor rail is supported on ceramic insulators (known as "pots") or insulated brackets, typically at intervals of around 10 feet (3 metres).

Usually use the running rails act as the return conductor but some systems use a separate fourth rail for this purpose.

Benefits of Third Rail system:

• Eradicates Electromagnetic interference on electrical components

• Reduces maintenance costs.

• Offers high efficiency - a 750V dc system gives efficiency of 92-94%.

• More Rugged than an overhead contact wire

• Longer life expectancy.

• High reliability because it is fed on both sides by rectifiers from adjacent substations

• Lower comparative initial costs than an AC system.

• Cheaper Rolling stock

• Since no transformers are installed on board– Reduced Weight of the vehicles and Increased Passenger Capacity

METRO TERMINOLOGIES RELEVANT TO POWER DISTRBUTION

• RSS (Receiving Sub-Station)

• TSS (Traction Sub-Station)

• ASS (Auxiliary Sub-Station)

• Depot

• Viaduct

• Chainage

Key Features of BMRCL

Owner Bangalore Metro Rail Corporation Limited

Number of lines2 (Now)2 (Phase I Target- March 2015)4 (Phase II Target - December 2019)

Number of stations16 (Now)41 (Phase I Target - March 2015)102 (Phase II Target- December 2019)

Chief executive Pradeep Singh Kharola, MD

Operation

Began operation 20 October 2011 (2011-10-20)

Train length 3 coaches

Headway 10 – 15 minutes

Technical

System length 42.3 km (Phase I)114.39 km (Phase II)

Track gauge 1,435 mm standard gauge

Electrification 750V DC Third rail

Speed 40 km/h (Average) , 80 km/h (Top)

Other features of BMRCL

• Tunnel air conditioning

• Uses Composite DC Third rail

• Air conditioned coaches

• Automatic Train Protection System

• Derailment protection guards

• Wi-Fi enabled (the first metro in India to have this feature)

• Emergency voice communication

• Powerheart Automated external defibrillator to protect its commuters against death from sudden cardiac arrest

• Earthquake proof & rainwater harvesting

• The minimum fare is 10 and maximum fare of 15 for Reach-1

Levels of Underground station:

1. Concourse – level below the ground, that has escalators, ,ticket counters, DG rooms etc2. Platform - level below concourse that has tracks for commutation3. Undercroft- bottom most level , it consists of cable trays .

L&T’s scope of work

Electrical and Mechanical( E&M) works including Hydraulic, Fire safety systems, UPS, DG Sets for Seven Underground stations and associated tunnel sections of North-South and East-West Corridors of Bangalore Metro Rail Project-Phase-1

The seven underground stations under L&T ‘s scope are

1. City Railway, 2. Sir M Vishveshwaraya,3. VidhanaSoudha, 4. Cubbon Park, 5. Chickpete, 6. KR Market and 7. Kempegowda

I. ELECTRICAL WORKS: -- E&M Package

• Design, Preparation of Working or shop drawings

• Provision of :

1. Power & control cables

2. Main, sub main LV switchboards & rest other distribution boards

3. Interlocks & protection schemes for power distribution

4. Normal & emergency lighting arrangement

5. Plug & sockets for lighting in tunnel & station areas

6. Earthing system –Main Earth bus in ASS, Clean Earth system & Clean Earth Bus

7. Lightning protection system

• Interface & coordination with BMS contractor for development of suitable control schemes

• Ascertain power supply feeding arrangements for ECS, TVS, Lifts & Escalators ets

• Supply & Lying of GI conduits with accessories for PA, communication, Signaling systems.

II. HYDRAULIC WORKS:

• Provision of:

1. Pumping arrangements

2. Automatic control & monitoring of operation of pumps

3. Feeding arrangement of various pumps

4. Pipeline network with control valves, water treatment to suit ECS requirements

III. FIRE FIGHTING & PROTECTION WORKS

1. Complete Fire suppression system in UG stations and associated tunnel sections & ancillary buildings including hydrants, hose reels, sprinkler system, fire hose cabinets, portable extinguishers, gas based flooding system etc

2. Fire Detection & Alarm system including monitoring & control through SCADA.

Designated contractors

General Consultants: RITES-OC-PBI-SYSTRA Detail Design consultants: Mott MacDonald Civil works: CEC & SOMA Traction : ABB Telecom: Thales Signaling: Alstom HVAC: Bluestar Tunnel fans: ETA Elevators, Lifts, Escalators: Johnson

Other interfaces excluding E&M

Lifts and escalators Railways electrification( DC Traction)

Auxiliary substation( up to the provision of bus ducts from transformer to LV main switch board)

SCADA and UPS Track work and Rolling stock Signaling and telecommunication

EARTHING PHILOSOPHYEarthing:

To understand the earthing codes and practices, we have been provided with the Indian Standard 3043 (Code of Practice for Earthing). We understand various earthingphilosophies followed in industries and are briefly described here.

In electricity supply systems, an earthing system or grounding system is circuitry which connects parts of the electric circuit with the ground, thus defining the electric potential of the conductors relative to the Earth's conductive surface. The choice of earthing system can affect the safety and electromagnetic compatibility of the power supply. In particular, it affects the magnitude and distribution of short circuit currents through the system, and the effects it creates on equipment and people in the proximity of the circuit. If a fault within an electrical device connects a live supply conductor to an exposed conductive surface, anyone touching it while electrically connected to the earth will complete a circuit back to the earthed supply conductor and receive an electric shock.

Earthing methods

The choice of these methods governs the measures necessary for protection against indirect-contact hazards.

The earthing system qualifies three originally independent choices made by the designer of an electrical distribution system or installation:

The type of connection of the electrical system (that is generally of the neutral conductor) and of the exposed parts to earth electrodes.

A separate protective conductor or protective conductor and neutral conductor being a single conductor

The use of earth fault protection of overcurrent protective switchgear which clear only relatively high fault currents or the use of additional relays able to detect and clear small insulation fault currents to earth

In practice, these choices have been grouped and standardised as explained below.Each of these choices provides standardisedearthing systems with three advantages and drawbacks:

Connection of the exposed conductive parts of the equipment and of the neutral conductor to the PE conductor results in equipotentiality and lower overvoltages but increases earth fault currents

A separate protective conductor is costly even if it has a small cross-sectional area but it is much more unlikely to be polluted by voltage drops and harmonics, etc. than a neutral conductor is. Leakage currents are also avoided in extraneous conductive parts

Installation of residual current protective relays or insulation monitoring devices are much more sensitive and permits in many circumstances to clear faults before heavy damage occurs (motors, fires, electrocution). The protection offered is in addition independent with respect to changes in an existing installation

Classification OfEarthing Based On System Earthing

 TT system (earthed neutral)  TN systems (exposed conductive parts connected to the neutral)  IT system (isolated or impedance-earthed neutral)

TT system (earthed neutral)

One point at the supply source is connected directly to earth. All exposed- and extraneous-conductive-parts are connected to a separate earth electrode at the installation. This electrode may or may not be electrically independent of the source electrode. The two zones of influence may overlap without affecting the operation of protective devices.

TN systems (exposed conductive parts connected to the neutral)

The source is earthed as for the TT system (above). In the installation, all exposed- and extraneous-conductive-parts are connected to the neutral conductor. The several versions of TN systems are shown below.

TN-C system The neutral conductor is also used as a protective conductor and is referred to as a PEN (Protective Earth and Neutral) conductor. This system is not permitted for conductors of less than 10 mm2 or for portable equipment.The TN-C system requires an effective equipotential environment within the installation with

dispersed earth electrodes spaced as regularly as possible since the PEN conductor is both the neutral conductor and at the same time carries phase unbalance currents as well as 3rd order harmonic currents (and their multiples).The PEN conductor must therefore be connected to a number of earth electrodes in the installation. Caution: In the TN-C system, the “protective conductor” function has priority over the “neutral function”. In particular, a PEN conductor must always be connected to the earthing terminal of a load and a jumper is used to connect this terminal to the neutral terminal.  

Fig.: TN-C system

TN-S system The TN-S system (5 wires) is obligatory for circuits with cross-sectional areas less than 10 mm2 for portable equipment.The protective conductor and the neutral conductor are separate. On underground cable systems where lead-sheathed cables exist, the protective conductor is generally the lead sheath. The use of separate PE and N conductors (5 wires) is obligatory for circuits with cross-sectional areas less than 10 mm2 for portable equipment.

Fig.: TN-S system

TN-C-S system The TN-C and TN-S systems can be used in the same installation. In the TN-C-S system, the TN-C (4 wires) system must never be used downstream of the TN-S (5 wires) system, since any accidental interruption in the neutral on the upstream part would lead to an interruption in the protective conductor in the downstream part and therefore a danger.

Fig: TN-C-S system

Fig.: Connection of the PEN conductor in the TN-C system

IT system (isolated or impedance-earthed neutral)

IT system (isolated neutral)No intentional connection is made between the neutral point of the supply source and earth

Fig: IT system (isolated neutral)

Exposed- and extraneous-conductive-parts of the installation are connected to an earth electrode.In practice all circuits have a leakage impedance to earth, since no insulation is perfect. In

parallel with this (distributed) resistive leakage path, there is the distributed capacitive current path, the two paths together constituting the normal leakage impedance to earth .

Fig: IT system (isolated neutral)

In a LV 3-phase 3-wire system, 1 km of cable will have a leakage impedance due to C1, C2, C3 and R1, R2 and R3 equivalent to a neutral earth impedance Zct of 3,000 to 4,000 Ω, without counting the filtering capacitances of electronic devices.

Fig: Impedance equivalent to leakage impedances in an IT system

IT system (impedance-earthed neutral)An impedance Zs (in the order of 1,000 to 2,000 Ω) is connected permanently between the neutral point of the transformer LV winding and earth (see Fig. E11). All exposed- and extraneous-conductive-parts are connected to an earth electrode. The reasons for this form of power-source earthing are to fix the potential of a small network with respect to earth (Zs is small compared to the leakage impedance) and to reduce the level of overvoltages, such as transmitted surges from the MV windings, static charges, etc. with respect to earth. It has, however, the effect of slightly increasing the first-fault current level.

Step Potential

Step potential is the step voltage between the feet of a person standing near an energized grounded object. It is equal to the difference in voltage, given by the voltage distribution curve, between two points at different distances from the electrode. A person could be at risk of injury during a fault simply by standing near the grounding point.

Touch Potential

Touch potential is the touch voltage between the energized object and the feet of a person in contact with the object. It is equal to the difference in voltage between the object and a point some distance away. The touch potential or touch voltage could be nearly the full voltage across the grounded object if that object is grounded at a point remote from the place where the person is in contact with it. For example, a crane that was grounded to the system neutral and that contacted an energized line would expose any person in contact with the crane or its uninsulated load line to a touch potential nearly equal to the full fault voltage.

Reducing Step and Touch Potential Hazards

One of the simplest methods of reducing Step and Touch Potential hazards is to wear Electric Hazard Shoes. When dry, properly rated electric hazard shoes have millions of ohms of resistance in the soles and are an excellent tool for personnel safety. On the other hand, when these boots are wet and dirty, current may bypass the soles of the boots in the film of material that has accumulated on the sides of the boot. A wet leather boot can have a resistance on the order of 100 ohms. Furthermore, it cannot be assumed that the general public, who may have access to the outside perimeter of some sites, will wear such protective gear.

Another technique used in mitigating Step and Touch Potential hazards is the addition of more resistive surface layers. Often a layer of crushed rock is added to a tower or substation to provide a layer of insulation between personnel and the earth. This layer reduces the amount of current that can flow through a given person and into the earth. Weed control is another important factor, as plants become energized during a fault and can conduct hazardous voltages into a person. Asphalt is an excellent alternative, as it is far more resistive than crushed rock, and weed growth is not a problem. The addition of resistive surface layers always improves personnel safety during a GPR event.

Also it is the industrial practice to have underground earthmat which is properly designed to bring touch and step potential to tolerable limits. There are provided in switchyards, Power generation stations, Metro rail stations, etc.

BMRCL Equipment DetailsI. DG SETS

It has Diesel engine integrated with alternator, engine mounted radiator, battery, battery charger and day service tank.

Piping with fuel handling system, lube oil system, air filters, exhaust piping and residential silencer.

Power and Control cabling system

Contains steel base frame, integral sound proof enclosure (acoustic enclosure) and anti vibrating mounting pads.

Satisfies the requirements of NFPA110.

Rating

750 & 1010 kVA, 415V DG Sets.

Power Factor-0.9 lagging (average) but at rated condition, load power factor is 0.8 lagging or better.

Operating mode –Used only for standby purposes supplying the rated loads for 8 hours with the rest period not less than 30 minutes.

Overload capacity-Reserve capacity-10% for one hour in twelve hours.

Ambient conditions-Maximum temperature 45º,Maximum Humidity-75%RH attitude:1000m(Above mean sea level)

Service Interval-running full load-less than 300 hours without maintenance adjustments and for 10,000 hours between major overhauls.

Shaft Speed-Not more than 1500 rev/min

Motor Starting-Largest motor set is require to start-18KW-Star-Delta starter

Loads-Operating in conjunction with non-linear and harmonics generating electronic loads in UPS Systems.

Cold Conditions

Start automatically-full rated loads (30sec) on failure of supply.

Jacketed water heating facility before starting pre-lubrication array.

Housing

Sound proof enclosure reduces the noise level of 75 dB at one meter distance from DG set enclosure.

Diesel Engine

Four stroke, multi cylinder –dynamically balanced with electronic fuel injection systems, turbo charged and intercooled suitable for heavy duty emergency operations.

Critical speed-Crankshaft-15% rated speed.

Engine-10% over load for one hour in 12 hour running period.

Engine fitted with heavy dynamically balanced flywheel for constant speed generator-BS649 requirements.

Engine Speed maintained-BS 5514

DG set parallel to another DG set-installation of an auto synchronizing panel suitable for PCC operation.

DG set provides continuous operation at ambient temperature for 8 hours.

Basic Engine

Connecting rod-heavy duty-forged special steel for handling power tariff.

Pistons are provided with piston rings and forced lubrication is employed to avoid any hotspot development.

Cylinder-lubrication-inner side with close tolerance-efficient output.

Air Intake System

Intake-air-force from engine room.

Ventilation system-DG sound proof enclosure.

Twin heavy duty air intake-BS72266

Turbo Charger

Driven by exhaust gas from cylinder.

Intercooled System

Compressed air-turbo charger-after cooled air heat exchange.

Enhance engine performance level and pre mature requirements of maintenance.

Exhaust System

High noise reduction muffler-correct position-exhaust pipeline.

Two silencers in series, one is located inside and other one is fitted on the roof of the generator building.

Minimum wall thickness of pipes and silencers-3mm.

Installation thickness-checked in tender-Max temperature is 50ºC on outside of pipe and supporting should be provided o withstand back pressure.

Silencer reduces sound level of 25dB by one meter form DG set.

Engine Cooling System

Engine cooled-water jacket-heavy duty air blast radiator.

Separate oil cooling is provided by cooling engine oil.

Lubricating System

Engine lubrication-closed circuit-wet sump, forced feed system

Forced lubrication uses lubrication filter with a minimum time period of 300 hours or more.

Lubricating oil pressure is monitored and on any fall below the recommended value, alarm is used and engine is safely shut down.

Fuel System

High speed diesel oil-IS 1460.

2 stage fuel filtration. The Fuel system-engine speed governor of electronic type.

Governor

Governor control- isochronous type –constant speed of engine at different load-maximum rating of machine.

Requirements

Steady state speed - + 1% of nominal speed.

Transient frequency change on application-rejection of 60% of load.

Max speed drop : 8%

Performance of governor under all load conditions – class A in BS5514:part 4(ISO 3040)

Starting System and Battery Charging

Starting system compromise-24V heavy duty sealed maintenance free, has lead acid battery and electric starting motor.

Provision to start engine from remote locations-from control panel or control room.

Automatic change over-battery charging-engine driven alternator at all times-generator set is running.

Automatic changer with automatic selection unit.

Alternator

Four pole, three phase, salient pole, self excited, revolving field, brushless type, self regulating and manufactured –IEC 60034.

Screen protected, fan ventilated, Neutral dip proof-IP23.

Capable of maintaining short circuit I, three times full load for a period of 3 seconds.

Alternator winding-insulation-Class H.

Transient performance-Clause 13.18.7.

Three neutral sides CT for differential protection.

Test temperature rise test of winding-100% of rated current.

Mounting and Package Generator

Fully painted anti corrosive plate.

Noise level restricted to 70dB at 1m from canopy.

Anti vibrationmounting is spring type between bedplate and floor prevents the vibration from being transmitted.

Metering

Parameter monitoring

Electrical-system DC voltages, AC voltages, AC current, frequency, real power, reactive power, power factor.

Engine-Lubricating oil pressure, exhaust temperature, RPM

Protections

Alarms.

Over speed, alternator winding temperature, start failed alarm, low oil pressure.

Engine protection/shut off parameters.

Over speed, low oil pressure, over ranking.

Electrical protection.

Loss of excitation, over and under frequency, over current, over and under voltages.

OPERATIONS

Manual start/stop-generator set.

Local and remote selection for the operation of generator set.

Engine speed/voltage control.

Fuel transfer control.

Provisions for PLC I/Ps &O/Ps

DG Battery voltage

DG Output voltage

Generator Control Unit

Manual start/stop of generators from LPGCP

Metering & alarm

Auto start/stop of generator for generator switch gears

Performance data transmission

Load management/load based auto start/stop/paralleling

Protection of generator sets

Active and reactive load sharing for generator sets

Automatic paralleling /Synchronizing of generator sets

Control Unit: - Electrical and System Protection

Features

Over current, earth fault and under voltage

Under frequency, reverse power and standby earth fault

Differential, alternator bearing/winding temperature high

Protection Of Operations

High water/oil temperature, low lubrication oil and high pressure.

High and low speed, alternator over pressure.

Fuel Tanks

Integral fuel day tank-capacity to run for 8 hours.

Tank constructed with mild steel BS 2594.

Fuel Filters

Supply line fuel filter-BS 4552

Fuel Pipe Work and Valves

Not limited to service filling pipe.

Bulk fuel tank to service tank pipes

Service tank vent pipe.

Generate fuel supply and return pipes.

Fire Protection

Multi sensor detectors

Ventilator in generator building.

II. LIGHTING

Operate at power factor not less than 0.95 lagging.

Conduit terminations with aluminum fittings and special accessories to prevent corrosion action.

All wiring within light fitting –heat resisting low smoke, zero halogen wires for normal luminaries and fire survival wires for emergency luminaries.

All light fittings-BS 4533

Specification for general requirements and tests-BS 4533

Photometric data for luminaries-BS 5225

Requirements for electrical installations, IEE wiring regulations 17th edition-BS 7671.

Fluorescent Luminaries

Supplied with HF, electronic ballasts.

Diffuses light subjected polycarbonate/glass, injection moulded, glass-not combustion-self extinguishing.

High intensity discharge luminaries

Installation of interior luminaries.

After installation remove dirt and debris from enclosures

Clean photometric control surfaces

Exterior Luminaries

Poles shall be set in the ground to a depth of 1030 m or one fifth of length.

Pole internal copper conductor, PVC installed IS 694.

Control gear-galvanized steel case mounted on or inside pole.

Emergency Lighting

Emergency lighting installation-NFPA 101 and NEPA 130, BS 5266,BS 4553,part 101 and part 102.22.

Emergency Luminaries

Clearly marked with labels visible to persons standing on floor beneath them.

Lamp Parameters

Linear fluorescent lamp

Metal ballide

High pressure sodium

Compact fluorescent

LED

Light Emitting Diode (Led) Based Fitting

LED based luminaries, in addition to LED module, provision for heat transfer-control gear, optical conditioning, mechanical support and protection as well as aesthetic switch elements.

III. SWITCHGEARS

Standards

BS 1432, specification for copper for electrical purposes: high conductivity copper rectangular conductors with rolled edges.

IEC 60439-1/EN 60439-1: Specifications for low voltage switch gear.

Switch Boards

Low Voltage Main Switch Boards(LVBs)

IEC 60255/EN 60255:Electrical protection relays

BS 381 C/BS 4800: Colours for identification, coding and special purposes.

BS 921 :Rubber mats

BS 1432: Copper for electrical purposes.

BS 7211-Thermosetting insulating cable

BS 5685 –Electricity meters

General Requirements

Totally Type Tested Assemblies (TTTA).

All type tests-IEC 60439-1 or EN 60439-1

LV main switch boards-fault containment tests-IEC 11641

Protecting earthing configuration TN-S

Service life-30years

Separate current transformer for each device.

Quality Control

Work man ship

All suitable items of LVSBs-completely interchangeable.

Tropicalisation

Encloses required degree of protection,`

Current transformer winding are epoxy resin capsulated against ingress of mixture.

LVSB Construction

LVSB is constructed by using 2mm CRCA thick sheet steel.

LVSB front and back access has maximum height of 2.3m

Degree of IP for LVSB –IP54.

Equipment is arranged within each component

It requires normal maintenance

SB-Rated sort time with stand current of 65KA for 1 second.

BS 951 & BS7430- the component parts of SB.

Busbars

Bus bars and bus connections – not exceed 90ºC.

Short time withstand current rating is 65KA for 1sec at 415V

Bus bar and bus bar connections-IEC 60439-1 or EN 60439-1

Separate insulating covers-BS EN 60216,IEC 60085 &IEC 60216-1

Polarity

2 pole, phase pole and neutral pole reacting top to bottom/left to right.

3 Pole, Red, Yellow, Blue And Neutral/Phase.

Internal and Control Wiring

All internal and control wiring-low smoke halogen(LSZH)-BS 7211

Control wiring-single core with min of 1.5mm2.

Bus wires are fully insulated.

Control Wires Are Protected By Msb.

Instrumentation

Instruments-similar in appearance throughout LVSB

Direct reading electrical meters -1S 13779/IEC 1036,687,1286

Meter is in continuous operation - 0ºC and 50ºC

Meters operation with CT/PT-RS 485/RS 232.

Relays

All control, interlock and alarm relays –EN60255 or IEC60255.

The relays are microprocessor based with auxiliary contacts – RS232/485.

The relays are provided with dust proof cases and flush mounting.

The relays are not affected by mechanical shock or vibration or by external magnetic fields.

Operating Coils

The fine wire operating coils with wire wound resistors are vacuum impregnated with insulating varnish.

Air Circuit Breakers (ACB)

All ACBs are from IEC-609472 or EN-60947-2

Frequency-50hz

Ambient temperature-45 ºC.

All ACBs are withdrawable type.

ACB mechanically robust construction.

Overload and short circuit characteristics are front adjustable.

Safety Shutters

Shutters cover each 3 phase group of stationary isolating restarts.

Transformer Incomers

Four pole horizontal draw out automatic ACB with normal current rating are present.

Two way tripping relays are provided.

Circuit breakers close/trip control switch is of piston grid type.

Control relay and wiring for automatic changeover interlocking/voltage sensing relay for automatic changeover are present.

Moulded Case Circuit Breakers (MCCB)

MCCB comply with and be type tested-IEC 60947-2 or EN 60947-2.

Each MCCB are fixed or withdrawable type.

The trip units are easily replaceable in same MCCB without changing MCCB.

All MCCBs arrange padlocking in OFF positions with locks provided.

The degree of protection is IP3X to IEC 60529 or EN 60529.

They have an electrical endurance of 1000 operating cycles.

The MCCB in low voltage main switch board store energy motorized and suitable for remote closing by BMS.

Contractors

They comply with IEC 60947-4-1 or EN 60947-4-1.

They are electro magnetically controlled, double air-break type. they are silver or silver faced.

They are modular in design and mechanically interlocked.

The making and braking capacity of contractors IEC 947-4

They are capable of being integrated into automated system without interposing components in minimum operating condition.

IV. UNINTERRUPTIBLE POWER SUPPLY (UPS)

UPS maintain continuous AC power supply to loads-emergency category loads.

Noise from UPS during operation should not exceed 55 dB at a distance from enclosure, over load range of 10% to 100% of rated full load ISO 3756/BS 4196:Part 6.

The design life is about 20 years.

They are modular in construction to facilitate unit replacement and all electronic cards shall permit plug in type replacement.

They are dust and vermiform proof with IP-33 to IEC 60529.

The UPS are provided with RS 232 & 485 for remote monitoring to extend alarm and status indications, communications and metering to BMS system located in station control room.

The system has operating efficiency, front access and self diagnosing features.

The heat producing devices are mounted on ample heat sinks.

The UPS as a whole are mounted on heavy duty fabricated steel base frame.

The UPS has low impedance with less than 50V, touch voltage and ripple content.

The UPS output voltage is in synchronization with main supply voltage feeding the static bypass switch.

The UPS are equipped with interlocking system to prevent parallel operation.

The UPS are capable of supplying non linear types of loads.

The UPS interface for remote monitoring of status and alarms.

The surge protective devices are used for protection.

Modes

Normal mode (mains up)

Stored energy mode (mains down)

Battery recharge(mains restored)

Automatic bypass mode (static bypass switch)

Built in/manual bypass (maintenance)

The UPS on taking unbalanced load shall be provided with H class insulation.

ELECTRIFICATION OF METRO RAIL STATIONSchematic layout diagram

The SLD is the single line schematic layout that gives the plan and layout of every equipment electrification, its cable layout, earthing layout etc.

The SLD for the city railway station was studied.

The Schematic layout diagram includes the following.

General schematics Panel wise schematic- with distribution boards Circuit Breaker Interlocking Lighting layout for concourse, platform and undercroft Ancillary building layout

Chiller pump room – basement Refuse,toilet, mess ,DG room – ground floor

Power socket layout Cable tray layout Lighting layout Protection layout Earth strip layout Main earth distribution Clean earth distribution Main earth mat location Clean earth pit location Earth details

There are two substations ASS I and ASS II that powers the main distribution board. Diesel generators are used as backup during power failure. UPS system is used for powering up the emergency loads.The various Distribution boards used are

DB 100 , DB 200 ------- main supply

DB 110, DB 210 -------- small power

DB 120, DB 220 -------- lighting

DB 150, DB 250 -------- B classified loads (Essential loads)

DB 151, DB 251 --------- escalator

DB 180, DB 280 --------- UPS

DB 130, DB 230 --------- Air handling unit

DB 140, DB 240 --------- Ventilation loads

DB 290, DB 390 --------- DG set

Classification of supply

All power supply equipment will have feeds from two auxiliary substations (ASS) so that failure of any ASS or single component will not result in a supply disconnection. Certain loads will have back up supply from the diesel generator and/or from the UPS.

‘A’ Classification (Emergency)

Derived from the station UPS, with 30 minutes standby. The station UPS is provided with dual incoming supplies from ASS and backed up from the diesel generator set with auto changeover. The devices under this class are

Station And Tunnel Emergency Lights Fire Alarm Panel Supply Control Circuits Station Control Room Signage Points All Over Station SCADA System Signaling And Telecom Equipments

‘B’ Classification (Essential)

Supply from both sub stations (with automatic changeover at substation level) and backed up with diesel generator set. The devices under this class are

ECS And TVS Equipments Fire Fighting Pumps Seepage Pumps Lifts Automatic Fare Collection Escalators Sewage Pumps Cross Passage Pumps Ramp Sump Pumps

‘C’ Classification (Semi Essential)

Supply from substation with automatic changeover at substation level. No generator back-up is provided. The devices under this class are

Chiller Plant Room Equipments AHU’s And Associated Filters Water Treatment Pumps

‘D1’ Classification (Normal)

Dual supply from both sub stations at distribution board level (no generator back-up), manual changeover is provided in the event of failure of any substation. Manual transfer switches are provided. The devices under this class are

Normal Lighting Small Power Sockets Advertisement Points Storm Water Pumps

‘D2’ Classification (Normal)

Supply from any one substation only, no generator back-up and no manual changeover. The devices under this class are

GSM/CDMA Room

Cables used in metro electrification:

The type of cable used for normal supply is generally XLPE with NO SMOKE & ZERO HALOGEN characteristics. Fire resistant cables are used for UPS supplies and they power up the emergency loads .

Fire resistant and fire retardant cable sheaths are design to resist combustion and limit the propagation of flames. Low smokes cables have a sheath designed to limit the amount of smoke and toxic halogen gases given off during fire situations.

Flame Retardant - designed for use in fire situations where the spread of flames along a cable route needs to be retarded

Fire Resistant (FR) - cables are designed to maintain circuit integrity of those vital emergency services during the fire

Low Smoke and Fume (LSF) - burns with very little smoke and fumes compared to standard PVC, fumes may contain halogens

Low Smoke Zero Halogen (LSZH) - when burns there is very little smoke and fumes (compared to standard PVC the fumes contain no halogens

Alternative names for LSZH - LSZO (Low Smoke Zero Halogen), 0HLS (Zero Halogen Low Smoke), LSHF (Low Smoke Halogen Free)

Fire Survival (FS) cables - Fire survival cables are used to maintain circuit integrity for designated period of time (3 hrs. in general) under fire. Same is used for all emergency feeders in a Metro station.

A comparison of common insulating materials is as follows:

Material Advantages Disadvantages

PVC Cheap

Durable Widely available

Highest dielectric losses Melts at high temperatures

Contains halogens Not suitable for MV / HV cables

PE Lowest dielectric losses High initial dielectric

strength

Highly sensitive to water treeing Material breaks down at high temperatures

XLPE

Low dielectric losses Improved material

properties at high temperatures

Does not melt but thermal expansion occurs

Medium sensitivity to water treeing (although some XLPE polymers are water-tree resistant)

EPR

Increased flexibility Reduced thermal expansion

(relative to XLPE) Low sensitivity to water

treeing

Medium-High dielectric losses Requires inorganic filler / additive

Paper / Oil

Low-Medium dielectric losses

Not harmed by DC testing Known history of reliability

High weight High cost

Requires hydraulic pressure / pumps for insulating fluid

Difficult to repair Degrades with moisture

VENDOR OFFER REVIEW REPORT

S.no SPECIFICATIONS Powerica - DG 750 KVA REMARKS

Generator Control Unit

1. Auto/manual selection Manual push botton In Compliance

2. Separate selection facility (key operated) - Details required

3. Auto mode – controlled by SG room Remote control In compliance

4. Manual mode-lockable selector switch - Details required

5. Starting with cranking cranking 3 attempts In compliance

6. Fail to start alarm Overcrank shutdown In compliance

7. Stopping when CB is open Alarm provided In compliance

8. Cool down time cycle

(0 – 300 ms) prior to starting(0-600 ms) prior to stopping

In compliance

9. Isochronous paralleling Available in PCU In compliance

10. Auto control of V,F, phase angle and sequence

within ±1.0% for any load between no load and full load

In compliance

11. Paralleling based on microprocessor Sensor based In compliance

12. Load sharing and managementIntegrated load sharing control system

In compliance

Protection against over voltage, earth fault, under voltage, over AmpSentry protective

Metering

1, Digital type display320*240 pixels LEd with LCD backlight In Compliance

2,

Electrical parameter mounting for System DC voltage Ac voltage AC current Frequency KW KVAR PF

Digital genset metering system In Compliance

3,

Engine monitoring for RPM Oil pressure Running hours

Service hours

SAE-J1939CANEngine controller In Compliance

4, Engine monitoring for Jacket water temperature Not specified Not applicable in India

5, Engine monitoring for Exhaust temperature - Details required

Protection

6, Alarm Start failure

Overcrank shutdown with warning In Compliance

7, Winding temperature shut down alarm - Details required

8, Over speed alarm Data available Details required

9, Service tank level( high & low) alarm - Details required

10, Low oil pressureHigh coolant temperature Data available Details required

11,

Electrical Protection Over current Under voltage Over voltage Under and over frequency Reverse power

Loss of excitation

present With shut down mechanism In compliance

12, Single phase protection - Details required

Operation

13, Remote selection of operation In PCC not in GCU In compliance

14, Engine speed control Within +/- 0.25% In compliance

15, Alt. voltage control Within +/- 1.0% In compliance

16, No load and manual test facility Clock interfaced test facility In Compliance

17, Volt free contacts for remote signaling of alarm - Details required

18, Signal isolators for remote signaling - Details required

19, Anti condensation heater control -Not required for Indian climate. Details required

20, Fuel transfer pump control -Level is sensed, no control, Details required

GENERAL REQUIREMENT

1. Steel base frame ISMC-300 In Compliance

2. Integral sound proof enclosure Composite type,75 db at 1m length In Compliance

3. Power factor Avg 0.80.9 at rated load In Compliance

4. Continuous operation for 8 hours, with rest not more than 30 mins Not specified Details required

5. Ambient conditions Temp 40 deg C No mention about humidity

6. Service interval Not specified Details required

7. RPM 1500 RPM In Compliance

8. Wake up time 30 seconds Not specified Details required

9. Pre lubrication arrangement Not specified Details required

Engine Details

10. Strokes 4 In Compliance

11. Multi cylinder 12 In Compliance

12. Turbo charged Not specified Details required

13. Critical crank shaft speed within 15% of rated

15010% of rated In Compliance

14. Sustain 10% overload in 12 hour running Not specified Details required

15. lubricating oil filters 4 paper element filters of 30 microns size In Compliance

16. air cleaner

2 air cleaners with filtering capacity of 15 microns with an efficiency of 99.7%

In Compliance

17. starter 2 starters of 24 volts ,9 KW In Compliance

18. battery charger

Battery charging alternator of 35 amps with 2.33/3500 drive ratio

In Compliance

19. Flywheel SAC 14 ( dimensions = 589,89,142 mm) In Compliance

20. Bearings Replaceable Ball bearings In Compliance

21. Air filter type Paper element In Compliance

22. Twin heavy duty air intake filters Not specified Details required

23. Silencer

2 silencer of 562 mm dia.

Muffler, 3mm thick

Details required about material used, ( galvanized steel is required)

about dBA at 1 m length

about insulation and thickness

24. Radiator Air blast Oil cooled In Compliance

25. Lubricating system Min. life 300 hrs. In Compliance

26. Fuel system P/T typeDetails required about 2 stage fuel filtration

27.

Governor

Isochronous type

Steady state band of +/- 0.25%

Class A1

Details required about frequency change on load rejection.

28. Starting system

Maintainable Battery

charging with 24V lead acid battery

Automatic changeover

With stop push button

Details required about starting time off engine from the receipt of command

No mention about trickle boost facility

ALETERNATOR

29. General requirement 4 POLE, 3 PHASE, 750 KVA Stamford make

30.Short circuit current bearing must be thrice of full load current in 3 seconds

Not specified Details required

31. Voltage regulation +/- 0.5% In Compliance

32. Ingress protection IP-23 In Compliance

33. Insulation Class H In Compliance

34.Transmission voltage deviation folowin step load of, must be55% is +/- 8% and 60% is +/- 10%

- Details required

35.

Mounting and packaging

With steel base plate and anti corrosive paint

In Compliance No mention about anti vibration mounting

36. Fuel tank

Integral fuel tank -8 hours , 990 lit

Drain at lowest point ,inlet at top

Direct level indicator

In Compliance

37. Fuel filter Element type In Compliance No mention

about firesensor

Diesel Generator SizingA 415V, 3phase 50Hz, Diesel Generator sets are been provided at each underground Metro stations for the back-up electrical power supply to essential and emergency services in the event of failure of regular electrical power supply. There are three modes of operation:

Normal mode - TVF is off Congested mode - TVF is on Fire mode - TVF running in reverse ,up going escalators on

Normal mode is when the train is freely travelling between the stations, the tunnel ventilation fans are off during normal mode.

Congested mode of operation is when there is no fire in the station but the train is struck in the tunnel area between two stations and the tunnel ventilation fans and the tunnel booster fans are required to work due to sudden congestion of the tunnel area.

During the fire mode, both the tunnel ventilation fans and the fire fighting pumps are on. The tunnel ventilation fans are operated in reverse mode to extract the smoke during fire.

Among the three modes of operation the maximum demand load on the station is during congested operation mode, hence the same is considered to arrive at the DG rating.

Steps for calculating the DG size:

Step 1: Decide the maximum load. It is known from the modes that the congested mode will have the maximum load as the tunnel fans will have to work.

Step 2: Estimate the engine size in KW. The factors to be considered here is the specification given by the client and the cost.

Step 3: Estimate the alternator size in KVA.

Step 4: Check the criteria for the Transient voltage dip (TVD).

TVD < 15 % at the starting of the Tunnel ventilation fan motor.

TVD = Xd

'

Xd' +C

X d' = Transmissionreactance of the alternator (given)

C = rated KVA (to be calculated) = Totalratingof 2 DG∈¿

Starting KVA load wen TVF is started

Starting KVA when TVF is started = (starting KVA of 180 KW motor) + (base KVA load when motor is started)

Base KVA = Max. load KVA – motor load in KVA (0.86 pf TVF motor)

Step 5:

Downstream load calculation.

The downstream load distribution is calculated and tabulated in the below format.

The individual board load for every distribution board is considered.

Distribution board start

Board load

Loads connectedIn KW

Working status

Supply class

Power factor

Load frequency

Diversity factor

MD factor

Total connected load in KW

Full load current in amps

KVAR

Total connected load in KVA

Later the loads have been summarized at main board level as shown below.

Switch board

Load dissipation

Connected load in KW

Total CLKW

Connected load in KVA

Total CLKVA

Overall DF

Total MD in KW

Total MD KVA remarks

ASS I ASS II ASS I ASS II

The distribution board column indicates the various DB’s like DB 100, DB 200 etc, and their respective individual loads are considered.

Status basically specifies the mode.S = standby

W = working

Supply class gives the classification of the supply

‘A’ Classification (Emergency)

‘B’ Classification (Essential)

‘C’ Classification (Semi Essential)

‘D1’ Classification (Normal)

‘D2’ Classification (Normal)

Power factor points to that of the systems.

Total connected load refers to every load that is powered by the system.

Load Factor =Maximum demand

aperiod

Peak load∈t h at period

Diversity Factor = Individual maximum demands of variousdivisions of a system

Maximum demand of t h ew h ole system

Diversity factor on working mode will be 1 and on standby mode will be 0.

Maximum demand Factor = MaximumdemandConnected load

LOAD DETAILS AND SWITCHGEAR SIZING

Basis of Calculations-

1. Lighting and small power loads are considered as per the actual loads based on the layout drawings and distribution board details.

2. Equipment data (i.e.) the preliminary data for ECS and TVS system are provided by the GC.3. Advertisement and Commercial loads are to be received from the designer. These loads are usually assumed.4. The references are taken from National Building Code of India, Outline Design criteria (ODC).

Load calculations-

1. The sizing of LT panels is done in terms of switchgear rating and number of feeders.2. Feeder quantity and sizing is based on grouping of loads according to classification of supply.

The downstream calculations and the upstream calculations are done for ASS I and ASS II under the following conditions: Load details for ASS I:

When both ASS I and ASS II are working, feeding their respective loads.

Load details for ASS II When both ASS I and ASS II are working, feeding their respective loads.

The load details are calculated panel wise when

ASS I is working ,ASS II is failed ASS II is working , ASS I is failed

Downstream load tabulations

Distribution

board start

Board

load

Loads

connecte

d

In KW

Workin

g status

Supply

class

Power

factor

Load

frequency

Diversity

factor

MD

factor

Total

connected

load in

KW

Full load

current in

amps

KVAR

Total

connected

load in

KVA

Later the loads have been summarized at main board level as shown below.

DB Name Power factor CL load in KW CL load in KVACL load in

KVAR

Full load current

in amps

Fault Level calculations of switchgearWhen a short circuit occurs in an electric system, heavy current flows through all the sections of the system which are in the

path between the power source and the equipment. The short circuit current is limited only by the impedance of the system.

This heavy current can damage the components of the electric system if they are not properly rated. If circuit breakers are not able to interrupt the high short circuit currents in a system, arcing and explosions may occur

The Rating of the components is done based on the maximum short circuit current.The short circuit current is calculated from the fault level KVA of the System.   The Fault Level in a distribution system is a very important parameter.  The kVA at the instant of a Fault should be correctly calculated and the components of the distribution system such as bus bars, circuit breakers, isolators, etc should be properly sized

Short Circuit Current (kA) for switchgear will be selected based on the 3 phase fault level (kA) of the board. Which can be arrived based on short circuit analysis of the system.

Distribution board start

Board load

Loads connectedIn KW

Working status

Supply class

Power factor

Load freq.HZ

DFMD factor

Total connected load in KW

Full load current in amps

KVAR

Total connected load in KVA

design current

Appr,Breaker rating

3 phFault level KA

Tabulation for the same is as follows.

LV Feeder cable sizingReference standards

IS 5819-(1970) recommended Short circuit rating of high voltage PVC cables

Assumptions

Voltage drop due to source during the steady state-compensated by OLTC power transformer and 100% voltage is maintained at source.

Design inputs

Load details

Load dissipation Voltage drop at above source during steady state (%)

System Inputs

System voltage (v) Frequency (f) Short circuit current withstand capacity at switchboard (I f ) Duration of fault withstand capacity (t) Apparent power of load (s) Load power factor (cos φ) Length of the cable (L) Efficiency (η) Maximum allowable steady state voltage drop at load terminals (V da) Source reactance (X s)

Environmental details

Ambient temperature (T)

Cable data

Voltage grade (V c) Number of cores Cross sectional area (A) Conductor material (copper/aluminum) Insulation Current carrying capacity

I cair I cgnd

Resistance of the conductor (Rc) Reactance of the conductor (X s) Short circuit current withstanding capacity of conductor (I sc) Number of runs selected (n)

Checking thermal ampacity

Calculation of derating factor for laying in ground

Derating factor for variation in ground temperature = G1

Derating factor for thermal resistivity of soil = G2

Derating of depth of laying = G3

Touching or spacing or trefoil spacing = G4

Overall derating factor = K-Gnd = G1*G2*G3*G4

Calculations of Derating factor for laying in air

Derating factor for air temperature = A1

Derating factor grouping = A2

Overall derating factor = K-Air = A1*A2

Calculations

The derated current carrying capacity of cable in air

I CDRA=I c Air∗K−Air (A)

The derated current carrying capacity of cable in ground

I CDRG=I C Gnd∗K−Gnd (A)

Derating capacity of the cable selected

ICDRA∗Runs

The current carrying capacity required for full load current

I L =S

√3 . V

Checking short circuit withstand capability

Short circuit withstand capability of selected size of cable = I SC∗n√ t

Resistance of cable for length selected R= RC∗L

1000∗n

Reactance for length of the cable X= XC∗L

1000∗n

3 phase fault current at load terminal = V

√3¿¿

Checking for steady state voltage drop

From phasor diagram,

V Ph= V L+ IRcosQ+ IXcos ( 90−Q )

Steady state voltage drop V d=I ( RcosQ+XsinQ )

% V d for this length = V d∗100∗√3

1000∗V

Total voltage drop = % V d+voltage drop at source during steady state ( give n )

RESULT

The cable is selected based on the calculated values

Thermal ampacity (derated current) Short circuit withstand capacity Steady state voltage drop

DISTRIBUTION TRANSFORMER SIZINGPurpose

To select the optimum sizing of the distribution transformer

Reference

IS 2026 – part I – gives the specification of power transformer IS 325 – gives the specifications of 3 phase induction motor

I

Q

V Ph

IXsin(90-Q)IX

IXcos(90-Q)

VIR

Assumptions

Voltage drop due to source during the steady state-compensated by OLTC power transformer and 100% voltage is maintained at source.

Design inputs

HV side voltage (V H¿ LV side voltage (V L¿ Frequency (f) Total maximum demand (MD) Total connected load (TCL) Design margin (DM) System power factor LV side phase voltage (V Ph¿

Largest rating motor data

Power rating Type of motor and starter Full load power factor and Starting power factor Ratio of starting current to full load current Full load efficiency Motor cable details ( dimensions, type and material used) Number of runs Length of cable (Lm¿ Resistance of cable (R¿¿m)¿ Reactance of cable (X m¿ Source parameters (KVA) and source fault (MVA)

Steady State capacity calculations

Transformer capacity required = MD

1−DM

Based on this the size of the transformer is selected.

Checking on capacity for transient conditions

Base load

BL= MD – P*MD/TCL/Cos φ

Base load current

I m1=BL∗1000

√3 V

Full load current of motor

I fl=P∗1000

√3 V L∗cosφ∗η

Starting current of motor

I st=1.2∗K∗I fl

Total starting KVA required = STLM + BL = transformer overload withstanding capacity (200%)

Overload withstand capacity of transformer = transformer overload withstanding capacity (200%) + selected size

Checking for voltage drop during largest motor starting

Base impedance at 1 MVA and given KV (Ω ) Source fault MVA Source reactance (X s¿

Transformer parameters

% impedance (Z) Transformer reactance (XT ¿ Net source reactance (XT +X s=X s 0¿

Phasor diagram

Calculations

From phasor diagram

V ph¿(V m cosQ+ I s Rm)2+(V m sinQ+ I S Xm+ I s X so+X so ( I m2−I m1 ))2

motor starting current

I s=I st V m

V Ph

bus voltage

V m cosQ

V ph

V b

V m

V m sinQ

I X X0

I s Xm

I s

V b ¿(V mcosQ+ I s Rm)2+(V m sinQ+ I S X t)2

So far from these equations

V ph2=(V m cosQ+

I st Rm V m

V Ph)

2

+¿¿

RESULT:

Using the rating of transformer KVA thermal loading on transformer during motor starting , voltage available at motor during motor starting, voltage available at bus during motor starting, the transformer size is selected.

Electrical Calculations – Lighting CalculationsThe lighting calculations has been carried out based on the outline design requirements from BMRCL, Design basis reports and design review discussions with general consultants. DIALUX software has been used for lighting calculations. The lighting fixtures have been selected to suit the architectural ceiling plan.

General inputs:

Height of the room in m Mounted height m Maintenance factor

We determine the following

The minimum lux in the corners Emin[lx] The maximum lux which is the concentrated intensity of light Emax[lx] The average lux in the room Eavg[lx] Reflection factor ρ [% ]

Utilization factor u0

For the surfaces: work plane, floor, ceiling and walls

From the determined parameters we decide the luminaries’ parts list.

CABLE SCHEDULEThe majestic interchange station was considered for cable scheduling during the internship period. Cable scheduling was done for power cables, normal earth and clean earth. The routing sequence of the cables was found out from the schematic layout diagram using true view software and the length of the cables are measured by using ZWCad software.

The routing sequence is tabulated as follows.

FromFrom(code) To To

(code) Cable ID Length in km

Insulation type Core Area

No of core and size

No of runs

Routing sequence

The beginning and ending points of the cable connecting every equipment in the station is considered and their ‘from’ and ‘to’ codes are generated. The cable ID is thus generated using the ‘from’ and ‘to’ codes to distinctly identify every cable, to ease the cable laying process during construction. The details of the cables namely, their length, insulation type (XLPE), Core type, Area , Number of cores, core sizes and the number of runs are tabulated as shown above.

The Routing Sequence is done by comparing the earthing layout with the combined service layout and according to the client inputs regarding the selection of trays for the respective cables in their route.

From the routing sequence the cable scheduling is done for calculating the free space available and proposing new sizes when there is contradiction. The cable schedule tabulation is shown below.

Route tag

SpaceReq.

Spec.Free space%

TotalSpaceReq.

Tray SizeProvided

No of trays

Space Avail.

Excess space avail.

Free Space %

Proposed TraySize

No of TraysProps.

Space avail.props

Free space avail.Props.

Type

Route tag: This gives the distinct tag given to every tray route.

Space required: Space required is calculated from the routing sequence and the size of that cable.

Specified free space %: This is given by the client with the idea of future expansion.

Total space required: It is the sum of the space required and the free space specified.

Tray size provided: This gives the size of the trays provided by the client.

Number of trays: It gives the number of trays provided.

Space available: This is given by the product of tray size and the number of cables. This gives the area available for placing the cables.

Excess space available: This is difference between the total space required and the space available.

Free space % : It gives the percentage of free space that is available.

Number of trays proposed and their area:If the free space % is in negative then new tray size or a new number of trays is proposed. If the free space available is too large, the proposed tray number or size can be reduced.

Type : this specifies the type of the tray that is given. It can be perforated or ladder .

Ladder cable trays Perforated

Thus cable scheduling is a very important work when laying cables. This is done to avoid overcrowding of cables in any tray and to avoid increased free space.

“There is NO Substitute for Hard Work.”Thomas Edison (1847-1931);

Inventor, Businessman

THANKYOU

B. SINDHUJA

M.G.VISHALI