BHEL Industiral Traning PPT

BHEL Industiral Traning PPT

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  BHARAT HEAVY ELECTRICALSLIMITED TRAINING SUMMARY ON TELECOMMUNICATION SYSTEMS Submitted To : Submitted By: Ms.Ashita Vermani Mr. Vikrant Negi ET-K, IV Yr
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  THE ORGANIZATION •Established more than 50 years ago • Primarily set up to meet the needs of the power sector in the country. • Largest engineering enterprise in India. • Operations cover conversion, transmission, utilization and conservation of energy in core sectors of the economy like Power, Industry and Transportation. •BHEL has 13 manufacturing divisions, 8 service centers and 4 Power Sector Regional Centers, in addition to over 150 project sites spread all over India and even abroad.
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  TELECOMMUNICATION •Telecommunication isthe assisted transmission over a distance for the purpose of communication. • It involves the use of electronic devices such as telephone, television, radio or computer
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  BLOCK DIAGRAM OF TELECOMMUNICATION SYSTEM
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  TELEPHONE EXCHANGE •Often called Telephone Switch • First telephone exchange was installed in 1878 • The first switching technology implemented was MANUAL SWITCHING which required an operator. • AUTOMATIC SWITCHING was introduced in 1891 and is of two types:- 1. ELECTROMECHANICAL 2. ELECTRONIC
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  1. Electromechanical switchinginvolved – STEPPING SWITCH called as the STROWGER SWITHING SYSTEM • It made use of a four number sequence to connect the call to a neighborhood • Later on, area codes were created. 2. Electronic switching system • Stored Program Control • Made use of computers as central control • High speed of operation
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  Fig. Electronic Exchange
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  ELECTRONIC EXCHANGES ElectronicExchanges are of two types: 1.Tone type: • sine waves are used. • speed of dialing for a given number is more than that of Pulse type. • Tone dialing handsets use a numeric keypad 2. Pulse type: • square wave is used due to which the dialing speed is lesser. • Pulse dialing handsets usually have rotary dials.
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  TONES USED INMODERN TELEPHONY 1.Dial Tone : •When handset is picked up from the cradle, then Dial tone is heard if a free line is available. •means that the instrument is ready to send the signals to the exchange. •This tone is a continuous burble sound of 400 Hz. modulated by 25Hz. and is sent to the calling subscriber as soon as his line seizes the free line. • The subscriber must not dial before receiving this tone; otherwise he is liable to get wrong connection.
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  2. Busy Tone: • When the called subscriber is engaged with other call, this tone is heard. It consists of a sound of 400 Hz. which is regularly interrupted at equal intervals. It is generally on for 0.75 sec. and off for also 0.75 sec. 3. Ringing Tone: • When a number is dialed then telephone of the called subscriber starts ringing. • Ringing tone of interrupted 400 Hz. supplies modulated by 25 Hz. • When this ringing tone is received, the calling subscriber knows that the connection is completed and that the bell of the called subscriber is ringing. 4. Number Unobtainable Tone: •This tone is sent when the number dialed cannot be obtained.
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  Powers providing circuits • Outside the exchange • Inside the exchange
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  Outside the Exchange: • The voltage supplied in Indian Subcontinent is 220-volts/50 Hz. A.C. but for the normal working of the exchange 48(46-53) volts of D.C. is required. • Hence a Rectifier circuit, backed with battery array for power-failures, is used. Inside the Exchange: •Inside the telephone exchange various types of power supplies are used for powering various modules (for example: - Line-cards, Ringer).
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  MAIN DISTRIBUTION FRAME(MDF) • It is place where both external and internal cables are terminated. • It carries all the protectors used in the exchange. • This M.D.F. is an ideal place for testing purpose. • Both the internal and the external cables are available at this frame and, therefore, both external and internal wiring and lines can be tested for this purpose.
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  MAIN DISTRIBUTION FRAME(MDF)
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  FREQUENCIES USED INTELEPHONY •High band tone (1216 Hz. to 1645 Hz.) •Low band tone (701 Hz. to 936 Hz.) •1 to 5 fall in low band •6 to 9, 0 fall in high band
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  HOOK SWITCH •Off-hookfor a tip condition or to describe a circuit that is in use (i.e., when a phone call is in progress) •On-hook for an idle circuit (i.e. no phone call is in progress)
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  TYPES OF CONNECTION 1) With wires i.e. cables 2) Wireless Microwave Links through Satellite CABLES : 1. Underground cables: These types of cables run under the Earth 2. Overhead cables
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  FAULTS IN ANEXCHANGE 1. Faults that occur from Line • Break fault Disconnection faults "Telephone is dead". • Loop fault Line-Shorting faults connectors are shorted • Earth fault: Wetting of connectors Connectors can either touch from earth, with other connector or with any conductor (such as metallic table, frame etc.) 2 . Faults that occur due to instrument Dial tone breaks after two or three rings. Instrument circuitry faulty.
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  FACILITY OF TELEPHONE •CONFERENCE-3 PARTY •LAST CALLER CALLBACK: 851 •APPOINTMENT REMINDER:852 then dial the time •LAST NO. REDIAL: 854 •CALL PICK UP: 89-xxxx to pick up a call ringing at another location xxxx. •CALL TRANSFER: 2 Parties conversing, any party can dial 3rd party, then Conversation among them Hang-up. The party on line now Talks to 3rd party
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  THANK YOU