The document provides information on the communication systems at the Guwahati Refinery, including the EPABX telephone system, WINTAP/ARP system for call monitoring and emergency alerts, network termination units, external telephone lines, and walkie talkie systems. It describes the different types of communication facilities available and provides details on the EPABX system and software used for call monitoring and emergency alerts.

1. SUMMER TRAINING REPORT
Indian Oil Corporation Limited, Guwahati Refinery
Duration: 15.06.2019 – 14.07.2019
Submitted by:
Dhurba Jyoti Boruah (1604168)
In partial fulfilment for awarding the degree of
BACHELOR OF TECHNOLOGY
IN
ELECTRONICS AND COMMUNICATION ENGINEERING
SCHOOL OF ENGINEERING AND TECHNOLOGY
NAGALAND UNIVERSITY

2. PREFACE
Industrial training plays a vital role in the progress of future engineers. Not only does it provide
insights about the future concerned, it also bridges the gap between theory and practical
knowledge. I was fortunate that I was provided with an opportunity of undergoing industrial
training at INDIAN OIL CORPORATION LTD, Guwahati Refinery. The experience gained
during this short period was fascinating to say the least. It was a tremendous feeling to observe
the operation of different units and processes. It was overwhelming for us to notice how such a
big refinery is being monitored and operated with proper coordination to achieve desired results.
During my training I realized that in order to be a successful engineer one needs to put his/her
concepts into action. Thus, I hope that this training serves as a stepping stone for me in future
and help me carve a niche for myself in this field.

3. ACKNOWLEDGEMENT
My indebtedness and gratitude to the many individuals who have helped to shape
this report in its present form cannot be adequately conveyed in just a few
sentences. Yet I must record my immense gratitude to those who helped me
undergo this valuable learning at IOCL ,Guwahati Refinery.
I am highly obliged to Training and Development Department of our university for
providing me this opportunity to learn at IOCL.
We would like to thank Mr. O.P Chetry,DGM and Mr. Suraj Kumar ( F&S) for
briefing us on orientation and their helpful words on fire and safety.
Our sincere gratitude goes to Mr. Aditya Jaiswal, AssistanceManager (Electrical)
and Mr. Amit Kumar Gupta (instrumentation Engineer) for their valuable
guidance.
Last but not the least, we are grateful to everyone who guided us in the field work.

4. CERTIFICATION
This is to certify that DHURBA JYOTI BORUAH, from School of Engineering & Technology,
Nagaland University has performed summer internship training for the specified number of days
under my guidance and supervision.
Mr. Aditya Jaiswal Amit Kumar Gupta
Assistant Manager (Communication Section) Instrumentation Engineer

5. CONTENTS
 Introduction to Guwahati Refinery……………………………………..1
 Fire and Safety …………………………………………….…..4
 Communication Systems………………………………………………...7-29
 Communication Facilities………………………………...…....7
 Epabx Telephone System………………………………………7
 Wintap/ARP System……………………………………..……..9
 Network Termination Unit…………………………………..…10
 Main Frame Distribution(MDF)/Krone………………………..11
 External Dot Lines…………………………………………......13
 Wireles sequipments………………………………………..….13
• Walkie-talkie……………………………………….…14
• Base Station………………………………….……….19
 Plant Communication System…………………………...……..23
 Fire Alarm………………………………………………...……25
 Different Types of Detectors………………………….………..26
 Sirens……………………………………………….………......28
 Instruments Used in Refinery for Parameter Management………..........30-41
 Pressure measuring devices……………………………… ...….31
 Flow Measuring Instruments………………………………………….…….…32
 Temperature Measuring Instruments………………………………….….33
 Level Measuring Instrument…………………………….…..…37
 Delayed Coker Unit (DCU)………………………………...……….42
 Conclusion …………………………………………….......44

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TOPIC 1:-Introduction to Guwahati Refinery
Guwahati Refinery is the country's first Public Sector Refinery as well as IndianOil's first
Refinery serving the nation since 1962. Built with Rumanian assistance, the initial crude
processing capacity at the time of commissioning of this Refinery was 0.75 MMTPA and
the Refinery was designed to process indigenous Assam Crude. The refining capacity
was subsequently enhanced to 1.0 MMTPA. Due to dwindling supply of indigenous
Assam Crude, Guwahati Refinery started processing Low Sulfur Imported Crude along
with Assam Crude. The supply of LS imported crude to Guwahati Refinery is from
Barauni Refinery via railway wagons.
The Refinery supplies various petroleum products to Northeastern India as well as
beyond, upto Siliguri end through the Guwahati-Siliguri Pipeline, spanning 435 KM,
which was the first Pipeline of IndianOil and commissioned in 1964. Most of the
products of Guwahati Refinery are evacuated through pipeline and some quantity also
through road transportation.
LPG, Naphtha, Motor Spirit (MS), Aviation Turbine Fuel, Superior Kerosene Oil, High
Speed Diesel (HSD), Raw Petroleum Coke and Sulfur are the products of this Refinery.
Auto fuels MS and HSD supplied by the refinery are of eco-friendly BS-IV grade as per
statutory guidelines of Government of India. The production of these valuable petroleum
products is through a series of different primary and secondary processing units along
with the associated auxiliary facilities like Captive Power Plant installed within the
refinery.
In the primary unit of the Refinery i.e. the Crude Distillation Unit (CDU), desalted crude
from the desalter is heated up through a series of heat exchangers and is fed into a pre
fractionator column. Here the lighter gases, LPG and unstabilised gasoline are separated.
The outputs from CDU are gasoline, Kero-I, Kero-II and Straight Run Gas Oil. Reduced
Coke Oil (RCO) which is the bottom product from the main fractionating column, forms
the main raw material for Coking unit and Indmax. In Naphtha Splitter section, total
Straight Run Naphtha is separated into three different fractions namely Light Naphtha
(LN), Reformate Naptha (RN) and Heavy Naptha (HN).
Delayed Coking Unit (DCU) with a capacity of 0.44 MMTPA is the main secondary unit
of Guwahati Refinery. The unit produces middle distillates from heavy ends. Main
feedstock to DCU is Reduced Crude Oil, which is heated to high temperatures of about
500oC in a furnace. Due to high temperatures, RCO is thermallycracked and yields
various hydrocarbon fractions like LPG, coker gasoline, coker kerosene, coker gas oil,
coker fuel oil, residual fuel oil and coke.

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INDMAX unit, in-house technology developed by R&D Centre of IndianOil was
installed for increased production of LPG and gasoline from heavy ends like Reduced
Crude Oil and Coker Fuel Oil. Indmax unit works on the Fluidized Catalytic Cracking
process similar to other Fluidised Catalytic Cracking Units. The first commercial unit
based on INDMAX technology was installed at Guwahati Refinery with a capacity of 0.1
MMTPA, and the capacity was subsequently enhanced to 0.15 MMTPA. Besides its
function of maximization of LPG, it enables the Refinery to upgrade its residual products
to high value distillate products.
Hydrotreating Unit with a capacity of 0.6 MMTPA produces High Speed Diesel (HSD),
Aviation Turbine Fuel (ATF) and Pipeline Compliant Kerosene (PCK) in blocked out
mode of operation. In HSD mode of operation, Sulfur content of diesel components ex
CDU, DCU and Indmax unit is removed and Cetane number is boosted. Smoke point of
Straight Run Kerosene component is improved in ATF and PCK modes along with
desulfurization. Hydrogen required for Hydrotreating is produced in Hydrogen
Generation Unit based on Steam Reforming technology.
Isomerization unit (45 TMTPA) produces MS component by improving Research Octane
Number upto 87.0 units and also helps in meeting the Benzene content specification of
MS.
INDAdept unit (35 TMTPA , developed by IOCL-R&D and EIL, removes Sulfur content
from Heavy Cut of Indmax gasoline to < 50 ppm to meet the Sulfur specification of BS-
VI quality MS.
The Sulphur Recovery Unit (5 TPD) in the Refinery takes care of the sour off gases from
the various units for removal of Hydrogen Sulphide. This is done by Amine treatment
after which H2S is converted to sulphur through Claus process.
Guwahati Refinery is amongst those Indian Refineries who have standardized their
various systems and has been awarded with ISO-9001 for Quality Management, ISO-
14001 for Environment management, OHSAS-18001 for Occupational Health and Safety
and ISO-27001 for Information Security management. Guwahati Refinery has also been

9. 3 | P a g e
certified with the ISO-50001 certification in recognition of its sincere efforts to manage
its energy usage in an efficient manner. Guwahati Refinery is also known for its sincere
efforts on development as well as implementation of effective Safety, Health &
Environment management systems and procedures along with good performance in
occupational health and safety.

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TOPIC 2:-
FIRE AND SAFETY
There are several types of fires, and also several ways to put them out. The three main fire
suppressants used are water, foam, and dry chemicals, and knowing their qualities can help you
optimize your firefighting abilities.
Water
Water has been the most popular fire suppressant throughout history, and can be useful in
fighting class A fires (fires made up of common combustible solids). Water is ineffective at
suppressing oil and electrical fires (Class B and C fires), and can actually be dangerous if used
on either. Water is also used to be mixed with firefighting foam and those class A fires are very
common, so water will likely continue to be a large part of fire suppression in the future.
Firefighting Foam
Firefighting foam was invented in the early 1900’s, and has evolved into various forms for
different types of fires. Type A foam was originally made for use against forest fires and is used
similarly to water. Type B foam is meant for liquid spills, and ARFF foam falls under this
category. ARFF foam has a low viscosity, and is able to cover large amounts of spilled jet fuel in
a short time period. Foam allows you to coat the materials that are burning, and then cut off the
oxygen to help suppress the fire.
Dry Chemicals
There are also various types of dry chemicals that are made for different purposes. Some of the
most popular are ABC chemical, Purple-K, and BC chemical. The ABC chemical is the most
versatile, and can be used to suppress all types of fires. Purple-K is useful when fighting liquid
fires.
Dry chemicals are frequently used in industrial settings, where chemical and electrical fires are at
a high risk. Dry chemicals are only used when needed due to the fine particulates that spread
easily over a large area and create a cleanup nightmare.

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Carbon Dioxide
Carbon dioxide removes oxygen to stop a fire but has limited range. It is environmentally
friendly and leaves no residue, so cleanup is unnecessary. Extinguishers with carbon dioxide are
usually used in contamination-sensitive places such as computer rooms, labs, food storage areas,
processing plants, etc.
Knowing which agent to use when fighting fires is important for everyone, not just firefighters.
Making the wrong selection could cause serious problems, so it’s important to do your research
first. Careful research and training will allow you to fight fires in the most effective manner
possible.

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TOPIC 3:- COMMUNICATION SYSTEMS
 COMMUNICATION FACILITIES
 EPABX TELEPHONE SYSTEM
 WINTAP/ARP SYSTEM
 NETWORK TERMINATION UNIT
 EXTERNAL DOT LINES
 MAIN FRAME DISTRIBUTION(MDF)/KRONE
 TELEPHONE

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COMMUNICATION FACILITIES
The various communication facilities available at Guwahati Refinery are:
1. Plant communication system (paging system)
2. Walkie-Talkie (wireless) system
3. Loud speaker announcing system
4. EPABX Telephone system
5. External DOT phones
6. Mobile /Cellular Phones
7. Fire Alarm Systems
8. Air Raid Protection (ARP) system
9. Group SMS Broadcasting system
10. Sirens
 EPABX TELEPHONE SYSTEM:
A private branch exchange (PBX) is a telephone exchange that serves a particular
business or office, as opposed to one that a common carrier or telephone company
operates for many businesses or for the general public. PBXs are referred to as:
 PABX: Private automatic branch exchange.
 EPAB: Electronic private automatic branch exchange.
EPABX stands for electronic private automatic branch exchange. The EPABX system
installed at the Guwahati Refinery is known as communication-6(CM-6). CM-6 is of
1484 lines and is installed at the Administrative building of Refinery equipped with the
Level DID (Direct Inward Dialling) facility.
The system is in operation with 57 junction lines provided for “0” dialling facility
provided for selected EPABX numbers and 2 Mbps stream(30circuits) for incoming level
DID facility.

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The communication between the exchanges is maintained by the tie-lines. The 2 MB
telephone line from E-10-B Panbazar Exchange (main exchange of Guwahati) is
connected to the Refinery EPABX via the NOONMATI RLU (Remote Line Unit) which
is a child exchange helping in distribution.
The number of various departments of the refinery consists of four digit numbers starting
from 7000 to 7999. A 259 code has been allotted to the IOCL by the city telephone
neglects the first two digits and sets the line to the telephone number specified. For
quarters telephone no starts from 8000 to 8999.
There are 12 internal hotlines provided to the plants in between control room to field
plants. Another line is at the MDF for checking the connection line pair.
The EPABX servers should provide the following features as a part of its telephone
functions:
 Call coverage: Minimum 5 independent coverage paths for various
incoming calls.
 Authorization code: 5 to 7 digit authorization code to make outgoing
calls thereby ensuring no misuse of the system.
 Call pickup: Call pickup within the group as well as outside group.
 Account codes: It should be possible to enter account codes before or
during a call. Users may be forced to enter account codes based upon their
class of service.
 Call Forwarding: Any extension should be able to transfer all incoming
calls temporarily to another pre-selected extension. Such request shall be
registered by dialling a code followed by the extension number. Facility
also exists of cancellation of a request registered earlier. This facility
should be available throughout a network.
 Call Transfer: Any extension user must be able to transfer call to another
extension without the help of attendant.
 Call Diverting: On busy, On No Response, after specific specifics
number of rings, etc.
 Call Bridging: Bridging calls from extension to cell phones.

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For the operation of some of the above mentioned functions, some software used in
exchange on Guwahati Refinery are as follows:
 WINTAP
 AIR RAID PROTECTION
(Emergency management software)
 WINTAP:
EPBAX should be provided the system tariff report. Tariff statistics should be
provided on incoming and outgoing trunk groups, attendant consoles, station hunt
groups, and individual stations. The information must include the number of calls
and call duration.
WINTAP is software which is used for monitoring and recording all the incoming
and outgoing calls, that is used for monitoring the call tariff. This software
provides all the information about call rates, call duration, incoming and outgoing
calls, STD or LOCAL calls or within the intercom.
 AIR RAID PROTECTION (ARP):
Air raid protection is an emergency management system. This is used in
emergency situation like fire in refinery. In case of emergency situation the “FIRE
AND SAFETY DEPT” record and store the emergency message 5 times by
bailing the 139 through the intercom and then the emergency management system
conveys the message to all the DGMs, HODs at the same time. After receiving the
message they have to rush to the place where the emergency has occurred. This
system is regarded as Air Raid Protection. The emergency software monitors this
ARP system. This software reports the success or failure of the ARP system. This
software is developed by VOICE-GATE.
ARP in Guwahati Refinery in brief points is as follows:
 It provides simultaneous ring to 24 telephone subscribers.
 It covers 24 numbers to the EPABX exchange.
 This system can be activated from fire stations control room through the
auto-telephone number by bailing 139.
 The caller has to make his message loud and distinct and repeat it several
times for about 15 to 20 seconds.

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 This is one directional communication. The subscriber of that respective
numbers can only hear the message, but cannot answer back.
The various classes of Restriction (COR) facilities in Refinery exchange are
as follows:
 COR 1:Non-Zero dial.
 COR 2: Zero dial with less frequency.
 COR 3: Zero dial with high frequency.
 COR 4: COR 3 with local dial.
 COR 5: COR 4 with STD.
 COR 6: COR 5 with high frequency.
 NETWORK TERMINATION UNIT (NTU):
A network termination unit (NTU) is a device that links the customer-premises equipment (CPE)
to the public switched telephone network (PSTN). The device serves as the last point of
connection between the two. Typically, the service provider is the owner of the NTU, which
usually supports various communication standards, including protocols and voltages, to allow
different device types to communicate with the PSTN.
The Guwahati Refinery exchange has a direct link with the BSNL exchange, Panbazar through
fibre optic cables. So it requires a remote NTU for this purpose. The Refinery exchange uses a
modem as per the convenience. Ti is a stand-alone HDSL NTU/LTU that enables the
transmission of 2048 kbps E1 data streams over a pair of unconditioned twisted pair lines, using
the High Bit Rate Digital Subscriber Line(HDSL) technology.
Network termination unit

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 MAIN DISTRIBUTION FRAME:
In telephony, a main distribution frame (MDF or main frame) is a signal distribution frame for
connecting equipment (inside plant) to cables and subscriber carrier equipment (outside plant).
The MDF is a termination point within the local telephone exchange where exchange equipment
and terminations of local loops are connected by jumper wires at the MDF. All cable copper
pairs supplying services through user telephone lines are terminated at the MDF and distributed
through the MDF to equipment within the local exchange e.g. repeaters and DSLAM. Cables to
intermediate distribution frames (IDF) terminate at the MDF. Trunk cables may terminate on the
same MDF or on a separate trunk main distribution frame (TMDF).
The most common kind of large MDF is a long steel rack accessible from both sides. On one
side, termination blocks are arranged horizontally at the front of rack shelves. Jumpers lie on the
shelves and go through an insulated steel hoop to run vertically to other termination blocks that
are arranged vertically.
With disciplined administration the MDF can hold over a hundred thousand jumpers, with
dozens changed every day, for decades without tangling.
MDF (Main Distribution Frame)
 KRONE:

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The Krone connection system is a reliable and cost effective technique for installation of
communications, broadcast and data wiring and has several advantages over solder tag methods,
including significant time and maintenance and benefits .Krone offers a comprehensive range of
connections and wiring system, based on a standard 10 pair (unscreened) termination module.
There is a complementary range of accessories for testing alternative equipment termination,
cable distribution and jumping. Krone uses an insulation displacement connection which totally
eliminates the need to strip, solder or screw connect wires.
Connections are made using KRONE INSERTION TOOL on a slot in the module. The slot
contains wire clamping ribs and two flexible metal contact arms at 45 degrees. These cut the
wire insulation and into the conductor, maintaining contact with spring force. A gas tight seal is
formed between the conductor and contact.
10 pair krone module
10 pair disconnection module
This is the most popular module used for audio and communications. It can be used for
termination of unscreened pair cable or for screened audio cable where the screen either common
terminates or floats at this connection point.
POWER SUPPLY FOR EPABX:
The EPABX requires 48V/40A DC supply. So an AC to DC converter is there which converts
the 3 phase AC supply to 48V DC supply. In case the main fails, the power back-up is given by
the 24 cell battery which can give power backup of about 8 hours.

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IP Telephone system
 EXTERNAL DOT PHONE (OR BSNL LAND LINE) IN GUWAHATI
REFINERY:
There are a total of 145 external DOT lines and 2 Nos. WLL provided at various locations
including residences of Senior Managers and Above. STD /ISD facility has been provided with
approval of Management wherever necessary. The breakup of the connections is as follows:-
• In addition there is a HOTLINE facility between our Fire Station and the City Fire
Service Station at Pan Bazar.
• Cordless phones have been provided at residences of HODs and above.
• Caller Line IDs have also been provided both at office as well as residence of officers on
need basis.
 Wireless equipments
A walkie talkie is a hand-held portable, two way radio transceiver. The first walkie-talkie was
used for military use during World War II and spread to public safety and eventually commercial
and jobsite work after the war.

20. 14 | P a g e
The major characteristics include a half duplex channel (only one radio transmits at a time
though any number can listen) and a push to talk switch that starts transmission. Typical walkie-
talkie resembles a telephone handset, possibly slightly larger but still a single unit, with an
antenna sticking out on the top. Where a phone’s earpiece is only loud enough to be heard by the
user, walkie-talkie’s built in speaker can be heard by the user and those in the immediate
vicinity.
Conventionally known as Public Mobile Radio Trunking Services (PMRTS), it allows a group of
people to communicate with each other, even if some or all of them are on the move.
ADVANTAGES OF PMRTS OVER CONVENTIONAL RADIOS:
1) Shares equipments such as repeaters in a more effective and cost efficient manner.
2) Increases probability of obtaining free channels, less waiting time and improved
productivity.
3) Improves privacy of communication
4) Efficient use of spectrum
5) Eliminates the need to monitor channel before transmitting.
 ADVANTAGES OF Wireless equipments:
1) Push to talk button (PTT): Instant communication at the push of a button.
2) Unlimited group size for conferencing with private call facility.
3) Clutter-free, city wide coverage.
4) No scope for misuse and external distraction.
5) Mission critical messaging facility, both group and one to one.
6) Unlimited talk time at low fixed call.
7) Best suited for emergency response and crisis management
8) No waiting, no dialling, no network congestion
9) Total command and control: Management by listening in.
CLASSIFICATION OF WALKIE-TALKIE:
1) Fixed Walkie-Talkie:
Walkies positioned at a central site like an office or headquarters where the manager can
maintain contact with the field staff. The equipment at such a site is termed as base
Station.
2) Mobile Walkie-Talkie: Walkies installed in vehicles are referred to as Mobile Walkie.
3) Portable Walkie Talkie:

21. 15 | P a g e
Walkies small enough to be carried around in hand are referred to as Portable Walkie
talkies.
ADVANTAGES OF DIGITAL WALKIE TALKIE OVER ANALOG
WALKIE TALKIE:
Walkie-talkie sets are in use in Refineries for communication purpose. Digital wireless
equipment’s are more advantageous than analog one. Noise reduction & clear voice is the
basic advantage of digital walkie talkie over analog one. Simultaneous talking paths (i.e.
2 groups can communicate using one repeater), unit ID, status buttons, text messages,
GPS tracking, Frequency management are some of the additional advantages of Digital
Walkie talkie which is absent in analog type of walkie talkie.
Operating instruction for Digital walkie talkie set

22. 16 | P a g e
Channel Number Allocated to
1 Channel 1
2 Channel 2
3 Channel 3
4 Channel 4
5 Channel 5
6 Channel 6
7 Channel 7
8 Channel 8
9 Channel 9
10 Channel 10
Operating instruction for Digital walkie talkie sets
 Walkie talkie can be turn on/turn off by using Volume Control switch & adjust its
volume level.
 Select desired channel by channel selector switch.

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 During giving message, Ensure Push to talk (PTT) button remains properly pressed. An
indicating LED just near channel selection switch will glow, if PTT is pressed.
 When we press PTT button, there is a beep sound. Message to be given after beep sound
only.

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 For receiving message, Ensure Push to talk (PTT) button is released.
 Use of P1 & P2: P1 for Check the ID of the handset; P2 for Contacts.
Do’s and Don'ts
 Press the PTT Button and speak clearly about 2.5 to 5 cm (one to two inches) away from
the microphone.
 All users are advised to press PTT (Push to talk) button only during the time of
transmitting message and will be kept free for rest of the time.
 Keep your conversation brief and to the point and make use of word “OVER” after
completion of message.
 Do not put the set on charger when battery is charged. Walkie Talkie set should be put on
charger only when battery is discharged.
 If the charged walkie talkie is put on charger, it will reduce the life of battery and will
create problem in the set.

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Procedure of sending message using Digital walkie talkie sets
Message can be sent to One group, All groups or any particular set (or ID) from a digital
walkie talkie set to another digital walkie talkie set, when it is in digital channel (All channel
except channel no: 2).
Procedure is as follows:
1) Go to the desired channel, to which message is to be given.
2) Press OK
3) Move the highlighted beam to message with UP/DOWN button
4) Press OK.
 Move highlighted cursor to compose and press ok.
 Type message using alphanumeric key and press ok.
OR
 Move highlighted cursor to quick text and press ok
 Select relevant quick text message and press ok.
5)
 How to send message to One group or All groups:Select the group and sent the
message
 How to send message to any particular set (or ID):Select the manual dial, enter the ID
of particular set and press ok.
 BASE STATION:
Base station systems are used to provide instantaneous one-to-one or one-to-many
communication. Base station can be on the form of stationary base stations or they can be
mounted on moving vehicles for maximum flexibility and reach. Its operation is like a walkie-
talkie. The wireless system works with the help of walkie-talkie sets. These are also called
portable radios.
Currently, there are about 17 base stations at Guwahati Refinery in use.

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STANDARD FEATURES OF BASE STATIONS:
1) Synthesized wide-band operation
2) Multiple coded squelch (private line and digital private line) capability.
3) Operator selectable channel scan
4) Field programming capability at dealer
5) High performance compact microphone with performance.
6) 10 feet power cable
7) 12V DC negative ground
8) 5 Watt internal speaker
9) Rotary volume control
10) On-hook monitor capability
11) Operator’s card and owner’s manual
ADVANTAGES OF BASE STATIONS OVER WALKIE TALKIES:
In some locations (mainly control rooms), where walkie talkie doesn’t work properly, since
control rooms are air tight and RF signal can’t pass through the signal to these control rooms,
(like New DDCS building of Guwahati refinery) base stations are used along with GP antenna
for reliable communication. The antenna of the base station can accept signals over a very large
area.
Fig: Base Station
REPEATER:
In digital communication systems, a repeater is a device that receives a digital signal on an
electromagnetic or optical transmission medium and regenerates the signal along the next leg of

27. 21 | P a g e
the medium. In electromagnetic media, repeaters overcome the attenuation caused by free-space
electromagnetic field divergence or cable loss. A series of repeaters make possible the extension
of a signal over the distance.
In a wireless communication system, a repeater consists of a radio receiver, an amplifier, a
transmitter, an isolator and two antennas. The transmitter produces a signal on a frequency that
differs from the received signal. This so-called frequency offset is necessary to prevent the
strong transmitted signal from disabling the receiver. The isolator provides additional protection
in this respect. A repeater when strategically located on top of a high building or a mountain can
greatly enhance the performance of a wireless network by allowing communication over distance
much greater than would be possible without it. At IOCL, there are presently three repeaters in
use which are installed at new admin building of Guwahati Refinery. They can support 6
channels at a time.

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TOPIC 4
 PLANT COMMUNICATION SYSTEM
 INTRONE-D
 FIRE ALARM
 DIFFERENT TYPES OF DETECTORS
 SIRENS

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 PLANT COMMUNICATION SYSTEM (PCS):
The plant communication system comprises of two types of channel for two –way
communication facility between the control room and the field.
 Page Channel: It provides loud speaking facility and is used for
broadcasting messages or issues instruction or to locate field operator in
the plant. The announcements made by the users are heard over the field
loud-speakers.
 Party channel: It is used for carrying prolonged conversations in private
mode, which is not heard over the loudspeakers. The system posses
multiple party channels. One dedicated channel for each field handset
station. Thus each field operator can carry his separate, independent and
simultaneous conservation
 The field call stations (FCS) and loudspeakers are installed at various
locations throughout the facility. The FCS and loudspeakers are indoor
type for indoor areas, weather proof type for outdoor areas and explosion
proof type for hazardous areas. The system provides excellent reproduction
of sound, clear audible announcements and high intelligibility of speech,
even in high noisy areas.
KEY FEATURES:
 Paging and alarm broadcasting facilities.
 Master-slave configuration with facility to connect multiple master control
desks.
 Direct communication between the field and control room operator.
 Direct communication between the two field-operators (without routing
any calls through central control room).
 Communication between two field operators with the help of MCS.
 Individual zone, multiple zones and all zones selection for announcement.

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 Digital display at MCS for identification of field call stations
number/name.
 Access to features can be restricted (by software programing) for few call
stations.
 Open system to facilitate its integration with EPABX, fire alarm etc. It is
the main communication link among the various units of refinery.
Presently one plant communication system is in operation.
MCS are equipped with push button type dialing pads with numbers so that the FCS and other
MCS can be called dialing.
FCS: The FCS when pressed towards left it makes an all-call and when pressed towards right it
makes call to MCS to which it is connected. In this FCS push button dialing pad is also provide,
so that direct communication between various FCS is possible. By dialing, even the MCS can be
reached from the FCS.
Various components of Plant communication system:
 Auto Transformer: input supply 230v AC UPS supply 10.5 KVA step down xmer (50 HZ
110V AC supply)
 Rectifier Module & DC to DC converter: 110v AC to 67v DC, Rated load: 23A, there are
4 module installed at pcs of Guwahati Refinery.
 Power Controller: It is used to manage equal sharing of load among the rectifier modules
and monitors system parameter.

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Auto-transformer
FIRE DETECTION AND ALARM SYSTEM
OPERATION PHILOSOPHY:
FIRE ALARM SYSTEM COMPONENTS:
Input devices:
Input devices include Multi criteria smoke detectors, Heat detectors, Beam detectors and Manual
Call Points, Monitor Modules
Output devices:
Output devices are the hooters connected through control modules and other interlocks
connected through control relay module.

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Fig: Fire Alarm
OPERATION:
In case of a fire alarm condition in any of the detectors or breaking of glass of MCP anywhere in
the areas covered by the Fire Alarm system.
1) The particular Fire Alarm Panel (XLS1000) to which the detector or the MCP is
connected will indicate the Loop No and Device No of the device in alarm.
2) The graphical layout representation showing the exact location of the device will appear
on PC at the Building Management System Control Room.
3) Also the related hooters linked up through software with that particular detector/MCP
will start sounding.
4) All hooters can be activated manually by pressing appropriate key on the panel.
SYSTEM HARDWARE:
Manual Call Points:
The MCP stations are addressable break glass type general alarm stations. The Manual Call Point
consists of an MS enclosure with a glass front. One NO contact is built into the enclosure.

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The contact changes whenever glass is broken and this changeover is sensed by the monitor
module and alarm is generated at the Fire Alarm Panel.
Application: To generate Alarm manually.
Fault Isolator Module:
The XLS IM Fault Isolator Module is used in Fire Alarm System Intelligent loop communication
circuits along with the other modules and sensors. This intelligent device enables part of the
Signature Data loop to continue operating should a short circuit occur.
Application: Isolating short circuit fault from the rest of the circuit.
Heat Detector:
The XLS-HRS Sensor is an intelligent ,rate of rise of temperature and fixed temperature type. It
has an integrated microprocessor and non volatile memory. It uses a custom integrated circuit
,provides two-way communication with the Controller. These are specifically used in places like
the kitchen where steam is generated.
Application: To detect abnormal increase in heat.
Fig: Heat Detector

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Multi Sensor Detector:
3D Multi Sensor Detectors are intelligent detection devices that provide two-way communication
with the Fire Alarm System. It has features like Fixed Temperature Heat Sensing Technologies
and non volatile memory. It also has an integrated microprocessor. The Fire Alarm system uses
a proprietary communication protocol containing both digital and analog signals which allow
each sensor to communicate its individual address, sensor type and analog value.
Application: To detect smoke.
Fig: Multi sense detector
SIRENS:
For warning systems (alarm, sirens) is to be installed by the industry to guard against accidental
pollution/mishap together with fire-fighting devices .Sirens have been installed at the refinery
site to alert workers on emergency and a complete fire-fighting network has been installed. Four
fire tenders are readily available at site in operation.
Purposes:Used in various purposes basically in safety issues.
 All clear

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 Major Fire
 Disaster
 Testing
Operations of the sirens are done manually from the fire station control panel only from refinery
shift manager’s room and quality control lab.
SIREN CODES:
Seven no’s of fire sirens of 5KM/ 8KM range are installed at different locations, inside as well as
outside refinery.
SL.NO. LOCATION AREA
1. Administrative Building Inside refinery
2. Quality Control Laboratory Inside refinery
3. OM&S Inside refinery
4. New DDCS Inside refinery
5. Sector-I Outside refinery
6. Sector-III Outside refinery
7. KV IOC, sector-1 Outside refinery
These are audible to all personnel of refinery and township. Sirens are regularly tested daily at
07:15 hrs from fire station by sounding straight for two minute. In addition to that Disaster siren
is tested on first day of month.
Fire siren code should be as follows:
1. SMALL FIRE: No siren
2. MAJOR FIRE: A wailing siren for two minutes.
3. DISASTER: Same type of siren as in case of Major Fire but the same will be sounded for
three times at the interval of one minutes i.e.( wailing siren 2min + gap 1 min + wailing
siren 2min + gap 1min + wailing siren 2min) total duration of Disaster siren to be eight
minutes.
4. ALL CLEAR (For fire): Straight run siren for two minutes.
5. TEST: Straight run siren for two minutes at frequency at least once a week.

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CONCLUSION:
Telecommunication is the most important unit in the refinery to maintain safety. Through
telecommunication all the departments of the refinery are connected. In Telecommunication unit
of the refinery there are various communication processes are available such as intercom, walky-
talky and Base station. In this section I came to know about EPABX system, Network
Termination unit, MDF, KRONE, Walky-Talky, Plant communication system etc.
TOPIC 4:-
Parameters measured and Controlled in Guwahati Refinery:-
Industrial Measurements consists of these FOUR broad categories:
• Flow
• Pressure
• Level
• Temperature
Other misc. measurement include
• Vibration, speed, pH, Conductivity.
• Analysis of So2, No2 in air, dissolved oxygen and silica in water etc.
Instruments used in refinery for parameter management:-
Measurement of temperature is done with the help of various devices. These devices are being
used in IOCL NOONMATI for the measurements of temperature are as follows:
Temperature gauge
Thermocouple
RTD
Temperature transmitter
None of these devices are connected directly to the line for it may damage the instrument.
An additional device known as thermo well is necessary to be installed in order to use
these instruments for the measurements of the temperature of various process fluids.
Types of Pressure

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There are three defined pressure references for measuring pressure. While there are other types,
like vacuum or sealed gage, all can be classified into these three categories. With diaphragm type
pressure sensors, it is easiest to understand the reference pressure as the pressure that is exerted
on the other side of the diaphragm from the process being measured.
 Absolute pressure
Measures the pressure relative to a perfect vacuum, using absolute zero as a reference point. An
example is a barometric pressure transducer. These also include sealed gauge, where the signal
has been offset to match the gauge pressure at the time of construction.
 Gauge pressure
Measures the pressure relative to atmospheric pressure. An example of this is a tire pressure
transducer. Also includes vacuum sensors, whose signals are reversed so that they signal positive
when the measured pressure is below atmospheric pressure.
 Differential pressure
Measures the difference between two pressures on each side of the sensor. An example is a
liquid pressure transducer where the fluid levels above and below the liquid are measured.
Pressure measuring devices:-
 Pressure Transmitters

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The most common pressure transducer constructions include a force collector such as a flexible
diaphragm and a transduction element that uses a dependent resistive, capacitive, or inductive
method to generate an electrical signal. The type of electrical device used will determine the
components used to build the pressure transducer.
 Piezoresistive strain gauge Pressure Transducer
A typical piezoresistive strain gauge pressure transducer utilizes strain gauges bonded to a
flexible diaphragm so that any change in pressure causes a small deformation, or strain, in the
diaphragm material. The deformation changes the resistance of the strain gauges, typically
arranged as a Wheatstone bridge, providing a convenient conversion of the pressure
measurement into useable electrical signal.
 Capacitance Pressure Transducer
A variable capacitance pressure transducer has a capacitive plate (diaphragm) and another
capacitive plate (electrode) fixed to an unpressurized surface with a gap of a certain distance
between the diaphragm and the electrode. A change in pressure will widen or narrow the gap
between the two plates which varies the capacitance. This change in capacitance is then
converted into a usable signal.
Flow Measuring Instruments
 Orifice Meter:-
When a liquid / gas, whose flow-rate is to be determined, is passed through an Orifice Meter,
there is a drop in the pressure between the Inlet section and Outlet Section of Orifice Meter. This
drop in pressure can be measured using a differential pressure measuring instrument.

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Since this differential pressure is in direct proportion to the flow-rate as per the Bernoulli's
Equation hence the differential pressure instrument can be configured to display flow-rate
instead of showing differential pressure.
The working principle of Orifice Meter is the same, as that of Venturi meter.
Temperature Measuring Instruments:-
 Bi-metallic Temperature gauge (0-700 0
C)

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The working principle of bimetallic thermometer depends on the two fundamental properties of
the metal.
1. The metal has the property of thermal expansion, i.e., the metal expand and contract concerning
the temperature.
2. The temperature coefficient of all the metal is not same. The expansion or contraction of metals
is different at the same temperature.
 Resistance Thermometers
RTDs (Resistance Temperature Detectors) operate under the principle that the electrical
resistance of certain metals increases and decreases in a repeatable and predictable manner with
change temperature.
 Thermocouples (TC’s)
Principle:-

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If two ends of dissimilar materials, welded together and placed at different temperatures, voltage
develops between the two ends (Seebeck effect). This voltage is called thermo Emf and the
device is thermocouple.The thermoelectric voltage produced depends on the metals used and on
the temperature relationship between the junctions. So for different range different type of
thermocouple is used.
In Guwahati refinery K type TC is used. Range (-) 185 to 1375 0C.
 THERMO WELL: This is a device which is used to avoid direct contact of the
temperature measuring device with the process fluid. Direct contact of the fluid with
the device may result in corrosion of vital parts of the device. Thus a thermo well acts
as a protective device and an interface between process medium and temperature
measuring device.
Temperature measurement in Pipes

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Level Measuring Instrument
 Magnetic Level Gauges:-
Magnetic Level Gauges provides clear,high clarity Indication of liquid level.Magnetic
Level Gauges are Principally designed as an alternative to glass level gauges.MLG's are
Now widely used in all industries as they aviod direct contact with Indicator system.It
eliminates need of glass for direct level indication and preverts chemical spillage due to
breakage of glass.

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Level measurement of open tank
The simplest application is the fluid level in an open tank. Figure shows a typical open tank level
measurement installation using a pressure capsule level transmitter

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If the tank is open to atmosphere, the high-pressure side of the level transmitter will be
connected to the base of the tank while the low-pressure side will be vented to atmosphere. In
this manner, the level transmitter acts as a simple pressure transmitter.
We have:
Phigh = Patm + S⋅H
Plow = Patm
Differential pressure ΔP = Phigh – Plow = S⋅H
The level transmitter can be calibrated to output 4 mA when the tank is at 0% level and 20 mA
when the tank is at 100% level
Closed Tank Measurement

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Should the tank be closed and a gas or vapour exists on top of the liquid, the gas pressure must
be compensated for. A change in the gas pressure will cause a change in transmitter output.
Moreover, the pressure exerted by the gas phase may be so high that the hydrostatic pressure of
the liquid column becomes insignificant.
For example, the measured hydrostatic head in a CANDU boiler may be only three meters (30
kPa) or so, whereas the steam pressure is typically 5 MPa. Compensation can be achieved by
applying the gas pressure to both the high and low-pressure sides of the level transmitter.
This cover gas pressure is thus used as a back pressure or reference pressure on the LP side of
the DP cell. One can also immediately see the need for the three-valve manifold to protect the
DP cell against these pressures.
The different arrangement of the sensing lines to the DP cell is indicated a typical closed tank
application
We have:
Phigh = Pgas + S⋅H
Plow = Pgas

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ΔP = Phigh – Plow = S⋅H
The effect of the gas pressure is cancelled and only the pressure due to the hydrostatic head of
the liquid is sensed. When the low-pressure impulse line is connected directly to the gas phase
above the liquid level, it is called a dry leg.
 RADAR and Ultrasound level instruments
Through AirRadar Ultrasonic Guided Wave Radar

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 Ultrasound level instruments
The time it takes for the instrument’s signal to leave the antenna, travel to the product, and return
to the antenna is calculated into distance.The instrument is spanned according to the distance the
100% and 0% points within the vessel are from its reference point.The measured distance can
then be converted into the end user’s desired engineering unit and viewed on the head of the
instrument or remote display.
Radar Technology

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Radar is a time of flight measurement..Microwave energy is transmitted by the radar. The
microwave energy is reflected off the product surface. The radar sensor receives the microwave
energy. The radar sensor receives the microwave energy. The time is converted to a distance
measurement and then eventually a level
.
Delayed Coker Unit (DCU)

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Delayed coking is one of the chemical engineering unit processes used in many petroleum
refineries. The main objective of the delayed coking unit is to convert low value residual
products to lighter products of higher value and to produce a coke product. In brief, the process
heats the residual oil from the vacuum distillation unit in a petroleum refinery to its thermal
cracking temperature in the heat transfer tubes of a furnace. This partially vaporizes the residual
oil and initiates cracking of the long chain hydrocarbon molecules of the residual oil into
hydrocarbon gases, Coker naphtha, and Coker gas oil and petroleum coke. The heater effluent
discharges into very large vertical vessels (called "coke drums") where the cracking reactions
continue to completion, forming solid petroleum coke which deposits out and accumulates in the
coke drums from which the product coke is subsequently removed. The diagram below depicts a
delayed coking unit with four coke drums (two pairs of two drums). However, larger units may
have as many as eight drums (four pairs of two drums), each of which may have diameters of up
to ten meters and overall heights of up to 43 meters. The yield of coke from the delayed coking
process ranges from about 18 to 30 percent by weight of the feedstock residual oil (currently 30
% ), depending the composition of the feedstock and the operating variables. Many refineries
world-wide produce as much as 2000 to 3000 tons per day of petroleum coke and some produce
even more. Globally, the total amount petroleum coke produced in 2010 was about 123,000,000
metric tons (123 Mt) and is expected to increase at an annual rate of about 5.6 percent. Petroleum
coke may also be produced in an oil refinery unit process that utilizes fluidized bed technology.
However, there are very few such facilities in operation and the amount of petroleum coke
produced via such technology is virtually insignificant. Another type of coke, commonly referred
to as "metallurgical coke", is the solid carbonaceous material derived from the destructive
distillation of low-ash, low-sulphur bituminous coal. Volatile constituents of the coal are driven
off by baking in an airless oven at temperatures as high as about 1,200 degrees Celsius (about
2,200 degrees Fahrenheit). Metallurgical coke is used as fuel and as a reducing agent in the iron
and steel manufacturing industries. The worldwide consumption of metallurgical coke was about
450,000,000 metric tons (450 Mt) in in 2010.
Flow diagram and process description
The schematic process flow diagram and description in this section are based on a typical
delayed coking unit with two coke drums. However, as mentioned above, larger units may have
as many as four pairs of drums (eight drums in total) as well as a furnace for each pair of coke
drums. Process description Residual oil from the vacuum distillation unit (sometimes including
high-boiling oils from other sources within the refinery) is pumped into the bottom of the
distillation column called the main fractionator. From there it is pumped, along with some
injected steam, into the fuel-fired furnace and heated to its thermal cracking temperature of about
365 °C. Thermal cracking begins in the pipe between the furnace and the coke drums, and
finishes in the coke drum that is on-stream. The injected steam helps to minimize the deposition
of coke within the furnace tubes. Pumping the incoming residual oil into the bottom of the main
fractionator, rather than directly into the furnace, preheats the residual oil by having it contact the
hot vapours in the bottom of the fractionator. At the same time, some of the hot vapours
condense into a high boiling liquid which recycles back into the furnace along with the hot
residual oil.

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As cracking takes place in the drum, gas oil and lighter components are generated as a vapour
phase and separate from the liquid and solids. The drum effluent is vapour (except for any liquid
or solids entrainment) and is directed to main fractionator where it is separated into the desired
boiling point fractions.
The solid coke, formed in the on-stream coke drum as the cracking reaction continues to
completion, is deposited and remains in the coke drum in a porous structure that allows flow
through the pores. Depending upon the overall coke drum cycle being used, a coke drum may fill
in 16 to 24 hours.
After the drum is full of the solidified coke, the hot mixture from the furnace is switched to the
second drum. While the second drum is filling, the full drum is steamed out to reduce the
hydrocarbon content of the petroleum coke, and then quenched with water to cool it. The top and
bottom heads of the full coke drum are removed, and the solid petroleum coke is then cut from
the coke drum with a high pressure water nozzle, where it falls into a pit, pad, or sluiceway for
reclamation to storage.

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CONCLUSION
Guwahati refinery, known as Gangotri of Indian Oil is well known for its achievements
during the last 56 years and all together, IOCL is always holding the fame of best Public
Sector Unit in India. Notwithstanding IOCL Guwahati has incorporated and installed
various extra ordinary and efficient equipment, but still more modernization is required
to keep the pace in the race. Immediate replacement of the highly priced equipment is not
at all possible, but through a proper plan or arrangement, it could be done within the
coming years. Microprocessor relay should be installed in order to increase the reliability
and stability of the power system and the operational and maintenance instructions for
such relays should be given to the people concernedbytheexperts.Itis obvious that
IOCLGuwahati has been striving hardto improve itsefficiencyandperformanceand to
givequalityproductsto the consumers ,andto achievethepeakandtomaintainitsglory;thestructural
reformsshouldbecoupledwith operationalreforms.