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AN INDUSTRIAL TRAINING REPORT

PARAS PRATAP

REG.No. (11/IEE/066)

At

C&S ELECTRIC LTD

MV DIVISION

GREATER NOIDA

(UTTAR PRADESH)

Submitted to

DEPARTMENT OF ELECTRICAL ENGINEERING

SCHOOL OF ENGINEERING

GAUTAM BUDDHA UNIVERSITY

GREATER NOIDA

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BONAFIDE CERTIFICATE

It is certified that the Industrial Training report is a work of Paras Pratap Reg.No. 11/IEE/066

from Gautam Buddha University (Greater Noida) who carried out the work in C&S Electric

Ltd.(MV Division) Greater Noida (Uttar Pradesh).

DR.YOGESH KUMAR CHAUHAN

(HEAD OF DEPARTMENT)

ELECTRICAL ENGINEERING

SCHOOL OF ENGINEERING

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ACKNOWLEDGEMENT

It is always a pleasure to remind the fine people in the engineering program for their sincere

guidance I received to uphold my practical as well as theoretical skills in engineering.

Firstly I would like to thank Dr.Yogesh Kumar Chauhan (HOD) and Mr.Rupendra Kumar

Pachauri Electrical Engineering for the positive attitude they showed for my work, always

allows me to question them and giving prompts replies for my uncertainties in all the fields

including educational, social and managerial work.

I express my immense pleasure and deep sense of gratitude to Mrs.Niyati Singh(C&S Electric)

and C&S Employees for spending there valuable time with me and also helped me in completion

of task.

Finally, I would also like to thanks Mr.Shailash Srivastav (HR) C&S Electric for giving me this

opportunity and guiding me during the course of the training.

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CONTENTS

Chapter no Topic Page no.

1 Introduction

Company Profile 6

2 About the Training

Plant layout 9

General plant layout

Process of store

Introduction to Ring main unit 14

Parts of RMU

Features of RMU

Types of RMU-Indoor &Outdoor

Types of welding 20

Tank assembly 23

Components of tank assembly

Working of components

Testing

Leak Detection Test 31

Final assembly of RMU 33

Components of RMU

Working of components

Final RMU

3 Conclusion 45

4 Reference 46

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Introduction

Company profile:-

C&S Electric Ltd. is amongst the leading suppliers of electrical equipment in India and is India’s

largest exporter of industrial switchgear. Its wide range of electrical and electronic products find

application in power generation, distribution, control, protection and final consumption. C&S

Electric is amongst the top 4 players in the LV switchgear business & the market leader in the

Power Busbar Business. In addition the company also has product offerings for MV switchgear,

Energy Efficient Lighting solutions and Diesel Generating Sets. C&S Electric along with Solar

EPC business also has an electrical contracting business which performs turnkey solutions for

industrial and commercial electrification, substations and power plants. C&S Electric was also

the 2nd company in India to design and execute a grid connected solar PV power plant in India.

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We are pleased to introduce ourselves as one of India’s foremost manufacturers of electrical

equipment for power generation, distribution, protection and control. We have 20 manufacturing

units in and around Delhi employing about 4000 people including 500 qualified engineers. We

also export our products to more than 74 countries around the globe. A sizeable portion of our

turnover is exported to USA, Europe, Russia Kenya, Brazil, Malaysia, Middle East, Australia

and other countries.

C&S Electric Ltd., through its 100% owned subsidiary, C&S Electric International BV

incorporated in “The Netherlands” have acquired Eta-com Group of Companies having offices in

Boom-Belgium and Horsham RH 13 5BB-Great Britain.

SPECIALITIES:-

Market leader in busbar business with dominating market share in India. C&S is amongst the

largest exporters of electrical switchgear products from India. 4000+employees and million of

satisfied customers, Over 24% CAGR for last 10 years

Website

http://www.cselectric.co.in

Industry

Electrical/Electronic Manufacturing

Type

Privately Held

Headquarters

222 Okhla Industrial Estate Phase 3 New Delhi, New Delhi 110020India

Company Size

1001-5000 employees

Founded

1966

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General Plant Lay-out:-

Gate entry process

Store (Incoming)

M.R.N (Material Receipt Note/ Inspection Note)

I.Q.C (Incoming Quality Check/Control)

Sampling Norms (Check)

M.R.N Clearance & back to store

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General Plant Lay-out:-

GATE ENTRY PROCESS

STORE

MRM (MATERIAL RECEIPT CUM INSPECTION NOTE)

IQC (INCOMING QUALITY CHECK

SAMPLING NORMS

CHECK

MRM CLEARANCE & BACK TO STORE

GATE ENTRY

STORE

RAW MATERIAL

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Store:-

Bill, Order No

Gate check

Store

Rejected Rack

Ok

Store Rack

(Put location)

Stored in Computer

Product

Manufacturing

Material Receive

Note

Quality

Check

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I.Q.C (Incoming Quality Control) :-

Customer Requirement Based

purchase Order (P.O)

Material Receive

Verified By store

M.R.N Generated By store against

System Generated (ERP)

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Income Quality

Inspection of the components received against

Particular M.R.N on Drawing

OK Not OK

Store (Stock) (Rejected) R.G.N

(Rejection

Generating

Note)

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INTRODUCTION OF RING MAIN UNIT:-

Ring Main Unit is enabled to install on medium voltage distribution network and mainly used for

protection of transformers in compact substations. It is used for medium voltage distribution in

compact substations, small buildings, and residential housing complex, large Shopping malls,

airports, wind power, etc. comprising medium voltage networks.

The concept of RMU is offering a choice of other switch-fuse combination or circuit breaker

with relay for protection of the transformer

RMU Parts:-

Protection Relay – operated by battery 1/2aa 3.6v

Current Transformer

Potential Transformer

Vacuum Circuit Breaker

Monometer

Constant - Green (gas not leaking)

Red - Slowly Down (Gas Leaking)

Battery

Command Input

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Features:

SF6 gas insulation & current interruption – No fire hazard

Maintenance free & sealed for life contact system

Outdoor installation

Robust construction

Tee-off circuit breaker with integral protection system

Low cost cable termination

Fully extendable options

Motorized mechanism

RMU is a compact ring main unit combining all MV functional units to enable to supply and

protect transformers on the secondary distribution network.

RMU can be supplied in various and different configurations suitable for most switching

applications in 12/17.5/24 kV distribution networks.

Technology

1. Metal enclosed unit for Indoor installation and type tested.

2. Insulated by SF6 Gas.

3. Maintenance free and easy installation.

4. Independent of climate.

5. ON-OFF-Earth, three position load break switch.

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6. Recyclable materials used.

Durability and usefulness

1. Metal enclosed tank is hermetically sealed; it means this is Independent of environmental

effects such as dirt, small insects, moisture and so on.

2. Load break switch operating is possible in the front of Ring Main Unit.

3. All switching operations can be made safely to personnel because of interlocking system that

operates automatically according to the switch position by the operator.

4. No requirement of recharging SF6 gas until its service life.

5. Remote operation available in case of using motor operating mechanism and FRTU.

6. HRC power fuse will trip the mechanism automatically by a fuse striker pin connected to

mechanism in the event of fault happening.

Safety

1. Approachable and operable safely in the presence of power in the cables.

2. Clear indication of operation status via mimic diagram on front panel.

3. Fully automatic interlocking system.

- Operation is only possible in case door is totally closed.

- Fuse compartment is only accessible when Load break

Switch is earthed.

- Voltage detector to check whether cables are lined or not.

4. Rupture disk is designed to protect devices in case of Emergency like gas expansion.

5. Internal arc withstand is tested for the operator safety in case of accident current occur.

(21kA/1s, without SF6 Gas)

Saving cost

1. No maintenance is required other than replacement of HRC Power Fuse after installation.

2. Compact design that requires minimum space to install and operate locally is main advantage

especially where the space is limited.

3. No additional costs for replacement because of long service life.

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4. Materials can be recycled after the end of its service life.

CB type RMU (LCL)

RMU offers a choice of solutions to make 2, 3 or 4 directional connections with line protection

by 630A CB, with network switching by switch-disconnectors with integrated power supply

telecontrol device.

1. L: LBS (Load Break Switch)

Three position Load Break Switch below 630A with disconnecting and earthing switch

2. C: VCB (Vacuum Circuit Breaker)

200A vacuum circuit-breaker for transformer protection 400/630A circuit-breaker for feeder

protection

3. Cable bushing horizontal in front

1. Ring S/W Earth operation

2. Circuit Breaker operation

3. Ring S/W operation

4. Pressure gauge

5. Earth S/W operation

6. Name plate

7. Voltage Indicator

8. Disconnector S/W operation

9. Cable compartment

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PRIMARY DISTRIBUTION PANEL – INDOOR

SECONDARY DISTRIBUTION PANEL – INDOOR

-OUTDOOR

INDOOR – GC

These units are suitable for indoor installation and can be made extensible on each side. Quick

break and air break is facilitated with the help of the manual i.e. fault making load breaking

switches, which are also known as RMUS. In order to control an incoming/outgoing 11 KV

feeder cable, these units come with allied bus bars and connections. These units are suitable for

11 KV systems.

Outdoor - GCT

These units are suitable for outdoor application and can be used as freestanding units. For

connections to industrial and commercial sites, these units are used in transformer substations,

distribution switchboards and ring distribution networks. Multiple panel switchboards are formed

by direct coupling of extensible ring switches; air insulated metering units and circuit breakers.

This process does not require accessing gas insulated chambers or additional cabling.

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Tank welding:-

Indoor ring main unit

Outdoor ring main unit

With canopy structure

Canopy Structure

In outdoor ring

main unit an anti-

theft security

system is provided

to protect it from

thieves and a

hardcover is

provided and

corrosion free

.and a canopy

structure to

protect it from

rain, snow etc.

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Types of welding:-

Mig(metal inert gas):-

MIG welding is an abbreviation for Metal Inert Gas Welding. It is a process developed in the

1940’s, and is considered semi-automated. This means that the welder still requires skill, but that

the MIG welding machine will continuously keep filling the joint being welded.

MIG welders consist of a handle with a trigger controlling a wire feed, feeding the wire from a

spool to the weld joint. The wire is similar to an endless bicycle brake cable. The wire runs

through the liner, which also has a gas feeding through the same cable to the point of arc, which

protects the weld from the air.

Stud Welding :-

Stud welding is a technique similar to flash welding where a fastener or specially formed stud is

welded onto another metal part, typically a base metal or substrate. The fastener can take

different forms, but typically fall under threaded, unthreaded or tapped. The bolts may be

automatically fed into the spot welder. Weld nuts generally have a flange with small nubs that

melt to form the weld. Weld studs are used in stud welding systems.

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TIG welding (tungsten inert gas welding):-

Is a manual welding process that requires the welder to use two hands to weld. What separates

TIG welding from most other welding processes is the way the arc is created and how the filler

metal is added! When TIG Welding one hand is used for holding the TIG torch that produces the

arc and the other hand is to add the filler metal to the weld joint. Because two hands are required

to weld; TIG welding is the most difficult of the processes to learn, but at the same time is the

most versatile when it comes to different metals. This process is slow but when done right it

produces the highest quality weld! TIG welding is mostly used for critical weld joints, welding

metals other than common steel, and where precise, small welds are needed.

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Dye Penetrant Inspection:-

Dye penetrant inspection (DPI), also called liquid penetrant inspection (LPI) or penetrant

testing (PT), is a widely applied and low-cost inspection method used to locate surface-breaking

defects in all non-porous materials (metals, plastics, or ceramics). The penetrant may be applied

to all non-ferrous materials and ferrous materials; although for ferrous components magnetic-

particle inspection is often used instead for its subsurface detection capability. LPI is used to

detect casting, forging and welding surface defects such as hairline cracks, surface porosity,

leaks in new products, and fatigue cracks on in-service components.

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Tank Assembly:-

1ts1dc both side PTC bushing ac

Components of Tank assembly:-

1. 3 Pole Structure (Vacuum Circuit Breaker)

2. Switches (Customers)

3. Isolators (Bushes)

Isolate between phases and body

4. Bus bars

5. Tank

6. Chassis

7. Mechanism

3-POLE STRUCTURE ISFG

SWITCH

ISFG

SWITCH ISOLATOR OR BUSHING

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Vacuum Circuit Breaker:-

A vacuum circuit breaker is such kind of circuit breaker where the arc quenching takes place in

vacuum. The technology is suitable for mainly medium voltage application. For higher voltage

vacuum technology has been developed but not commercially viable. The operation of opening

and closing of current carrying contacts and associated arc interruption take place in a vacuum

chamber in the breaker which is called vacuum interrupter. The vacuum interrupter consists of a

steel arc chamber in the Centre symmetrically arranged ceramic insulators. The vacuum pressure

inside a vacuum interrupter is normally maintained at 10 - 6

bar.

The material used for current carrying contacts plays an important role in the performance of the

vacuum circuit breaker. CuCr is the most ideal material to make VCB contacts.

Advantages of Vacuum Circuit Breaker or VCB

Service life of vacuum circuit breaker is much longer than other types of circuit breakers. There

is no chance of fire hazard as oil circuit breaker. It is much environment friendly than SF6 Circuit

breaker. Beside of that contraction of VCB is much user friendly. Replacement of vacuum

interrupter (VI) is much convenient.

Operation of Vacuum Circuit Breaker

The main aim of any circuit breaker is to quench arc during current zero crossing, by establishing

high dielectric strength in between the contacts so that reestablishment of arc after current zero

becomes impossible. The dielectric strength of vacuum is eight times greater than that of air and

four times greater than that of SF6 gas. This high dielectric strength makes it possible to quench

a vacuum arc within very small contact gap. For short contact gap, low contact mass and no

compression of medium the drive energy required in vacuum circuit breaker is minimum. When

two face to face contact areas are just being separated to each other, they do not be separated

instantly, contact area on the contact face is being reduced and ultimately comes to a point and

then they are finally de-touched. Although this happens in a fraction of micro second but it is the

fact. At this instant of de-touching of contacts in a vacuum, the current through the contacts

concentrated on that last contact point on the contact surface and makes a hot spot. As it is

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vacuum, the metal on the contact surface is easily vaporized due to that hot spot and create a

conducting media for arc path. Then the arc will be initiated and continued until the next current

zero.

Operational sequence for CB

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Chassis:-

45 Hardware

Shaft

Axle

Bearing

Small shaft

Mechanism (CD1):-

Closing shaft:-

Changing spring

Closing spring

Push button

Striker

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Adapter

Spangle

Counter

I bolt

After this motor is fitted in the chassis and the work of chassis is complete and the machine goes

to tank assembly.

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ISFG SWITCH:-

There are two switches:-

Input switch

Output switch

Two Types of Contacts are there:-

Copper

Silver Plated on Copper

There are 3 turns:-

Line Flow – To Flow

Earth - In Maintenance and Fault

Disconnect

Silver Plated for ON Condition

Copper Contact for Grounding

And in middle condition there is off position

Silver Plated copper s used for resistance control.

Operation of 3-Position Load Break Switch

Main Close Open earth

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TESTING OF VACUUM CIRCUIT BREAKER:-

Parameters r y b

Close time (MS) 42.3 42.5 42.6

Closing synchronism 0.30

(MS) Pass

Contact stroke (mm) 8.55 8.66 9.28

Velocity 1(m/s) 1.22 1.29 1.22

Velocity 2(m/s) 1.11 1.13 1.08

Max. Coil current 4.23 0.2

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Parameters r y b

Open time (MS) 35.70 35.70 35.60

Open syn. (MS) 0.10

Contact stroke (mm) 8.55 8.66 9.08

Over travel open (mm) 1.18 1.05 0.63

Over travel time open (MS) 8.40 6.80 5.30

Over rebound (mm) 0.69 0.52 0.55

Velocity 1(m/s) 0.32 0.50 0.36

Velocity 2(m/s) 0.79 0.91 0.76

Max. Coil current c1 c2 c3

0.26 2.31

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LEAK DETECTION TEST:-

Leak Detection & Gas Filling Machine

This is the best & largest machine in the South Asia in terms of size of the test chamber &

accuracy of Mass Spectrometer used to detect leakages in Ring Main Unit Tanks. The machine

will detect a leak of 6X10-6 mbar l/s at 300mbar, 100% Helium. The process is fully automated

with predefined cycle of evacuation, leak testing with Helium, purging with Nitrogen and then

filling of SF6 & leak testing with SF6 with no manual intervention.

The machine has a capacity of testing 15-20 tanks per day

18% Helium is used currently in the bag for leakage detection in the helium bag. Helium Gas is

the lightest gas

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Leakage Area in tank Assembly:-

Back cover Welding

Bearing

Bellow

Ext. PTC Welding

PTC Bushing

Tee-off Bushing

Extension Bushing

Protection Sheet

Dilo Valve

Leak not found

Air pressure low

Pressure Switch

Run Welding

Test Welding

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Final Assembly of Ring Main Unit:-

1- Lifting points

2- Cable test bushings compartment

3- Earth switch operating mechanism

4- Switch disconnector operating mechanism

5- Live cables indication neon lamps

6- LBS cable compartment access panel

7- CB spring charger operation shaft

8- Circuit breaker pushbuttons

9- Circuit breaker spring status

10- Pressure indicator

11- Self-powered protection relay

12- VCB cable compartment access panel

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The Enclosure is used for outdoor applications. Manufacturing of this enclosure with GI sheet

and Powder coated. The access is available for Installation of RMU and connection of earthing

from outside of enclosure for customer.Anti-theft door hinge and pad locking facility is available

in this enclosure.

Enclosure for Outdoor application

Electrical Data:-

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Load Break Switch:-

Standard features

1. Three position load break switch with disconnector and earthing switch

2. Operating mechanism with two separate shaft for load and earthing function

3. Switch position indication for LBS and ES

4. Cable bushing horizontal in front with integrated capacitor for voltage indication

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Optional features

1. Motor operation for load break switch

2. Auxiliary switches

- Load breaks switch position

- Earthing switch position

3. Voltage indicating system

4. Short circuit and earth fault indicator

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Supplied Configuration:-

Operating mechanisms:-

MECHCI1 (M) and MECHCD1 (M) operating mechanism elements Identification

1 -Function label holder

2 -Switch and earth switch status indicator

3 - Lock for "open" earth switch interlocking (optional)

4 - Pressure indicator

5 - Earth switch operation shaft

6 - Earth switch interlocking pin (prevents handle insertion)

7 - Live cables signaling lamps

8 - Lock for "open" switch interlocking (optional)

9 - Switch interlocking pin (prevents lever insertion)

10 - Switch operation shaft

11 – Circuit breaker closing operation pushbutton interlock (optional)

12 – Circuit breaker operation pushbuttons

13 – Circuit breaker status indicator

14 – Circuit breaker spring status indicator

15 – Circuit breaker spring charger operation shaft

16 – Circuit breaker operation counters

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17 – Self-powered protection relay

18 – Protection relay low voltage access panel

19 - Switch or Earth switch manual operation lever

Operating mechanism functional principle

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Circuit Breaker:-

Standard features

1.200 A vacuum circuit-breaker for transformer protection or 630 A vacuum circuit-breakers for

feeder protection

2. Three position disconnecting and earthing switch

3. Switch position indication for CB and DS/ES

4. Cable bushing horizontal in front

5. Interlocking between CB and DS/ES

Optional features

1. Motor operation for circuit breaker

2. Auxiliary switches

- CB position

- Disconnector position

- Earthing switch position

3. Voltage indicating system

Operating mechanism functional principle

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4. Trip coil and close coil

Vacuum interrupter:-

In the closed position, normal current flows through the interrupter. When a fault occurs and

interruption is required, the contacts are quickly separated. The arc drawn between the surfaces

of contact is rapidly moved around the slotted contact surface by self-induced magnetic effects,

preventing gross contact erosion and the formation of hot spot on the surface. The arc burns in an

ionized metal vapor, which condenses on the surrounding metal shield. At current zero they are

extinguishes and vapor production ceases. The metal vapor plasma is very rapidly dispersed,

cooled, recombined, and deionized, and the metal vapor

Products are quickly condensed so that the contacts withstand the transient Recovery voltage.

OCR (Current Relay): CT powered protection relay:-

This relay is self-powered relay by the CT in RMU and can be set with definite time and inverse

time characteristics for short circuit, overload and earth Fault current. Parameter setting can be

done in different user-friendly ways, computer controlled or with HEX switches on the front.

The relay is also provided with a digital memory for the storage of the most recent tripping

values. This relay has proven to be a reliable and widely accepted method of protection in

worldwide distribution networks.

CT (Current Transformer):-

A current transformer (CT) is used for measurement of alternating electric currents. Current

transformers, together with voltage (or potential) transformers (VT or PT), are known

as instrument transformers. When current in a circuit is too high to apply directly to measuring

instruments, a current transformer produces a reduced current accurately proportional to the

current in the circuit, which can be conveniently connected to measuring and recording

instruments. A current transformer isolates the measuring instruments from what may be very

high voltage in the monitored circuit. Current transformers are commonly used in metering

and protective relays in the electrical power industry.

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Voltage indicator lamps (Voltage Detector):-

It is a device to check the presence or absence of voltage in the cables. It is conforming to IEC

standard 61958. Push button type LED voltage indicator is provided and lamp power is supplied

by bushing type capacitive dividers.

Switch-fuse combination:-

Standard features

1. Three position switch-fuse combination with earthing switch

2. Switch position indication for switch fuse combination and earth switch

3. Cable bushing horizontal in front

4. Fuse holder for DIN type fuse-links

5. Fuse-link rating

- 12/17.5kV: max. 100 A, LSIS DIN type fuse-link

- 24kV: max. 75 A, LSIS DIN type fuse-link

6. Automatically tripped to protect from fault current when a fuse is blown

Optional features

1. Motor operation for switch-fuse combination

2. Auxiliary switches

- LBS position

- Earthing switch position

- Fuse blown status

3. Voltage indicating system

4. Trip coil

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Cables connection:-

RMU ID was designed to use separable pre-moulded (screened and unscreened) or thermo

retractile Connectors. The cables and connectors selection is a customer’s responsibility and

must be compatible with RMU ID equipment.

- Screwed Tee connectors or thermo-retractile connectors for 400/630A bushings, which

accommodate Copper or aluminum thermop lastic insulated cables, for Incoming/Outgoing

function.

MRB (Manual Reset Button):-

1. It is a function which resets a circuit breaker manually when a circuit breaker is tripped by

OCR.

2. When a circuit breaker tripped by fault current, a mechanical trip indicator (MRB, Manual

Reset Button) pops out from the main cover and the switch (SDE) which sends control signal

electrically is conducted to output the information occurred from fault circuit breaker.

3. MRB can be operated only by OCR but not by OFF operation of circuit breaker, To re-close a

circuit breaker after a trip, press MRB to reset it for closing.

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EFI (Earth fault indicator):-

EFI can be installed at RMU frame or anywhere customer wants.

1. Single Phase AC supply split core type sensor

2. Automatic resetting function on AC 220~230V3Ph

3. 3Phase

Routine quality check:- While producing RMU, various routine tests are taken for product capacity.

Tested items are as shown follows.

1. Filling pressure check

2. Tightness check

3. Manual and motor operation check

4. Dielectric check

5. Contact resistance check

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Final Ring Main Unit

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Conclusion

As an undergraduate of Gautam Buddha University. I would like to say that this training

program is an excellent opportunity for us to get to the ground level and experience the things

that we would have never gained through going straight into a job. I am grateful to C&S Electric

Ltd (Greater Noida) for giving us this wonderful opportunity. The main objective of the

industrial training is to provide an opportunity to undergraduates to identify, observe and practice

how engineering is applicable in the real industry. It is not only to get experience on technical

practices but also to observe management practices and to interact with fellow workers. It is easy

to work with sophisticated machines, but not with people. The only chance that an undergraduate

has to have this experience is the industrial training period. I feel I got the maximum out of that

experience. Also I learnt the way of work in an organization, the importance of being punctual,

the importance of maximum commitment, and the importance of team spirit. In my opinion, I

have gained lots of knowledge and experience needed to be successful in a great engineering

challenge, as in my opinion, Engineering is after all a Challenge, and not a Job

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References

Web

C&S Electric Ltd.

Wikipedia

Google images

Switchgear and Power System Protection by Ravindra P Singh

Switchgear Protection and Power Systems by Sunil S Rao