18-01-2013, 04:55 PM
Study on Telecommunication System in BHEL, Haridwar
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THE ORGANISATION: BHEL
BHEL, Bharat Heavy Electricals limited is the largest engineering and Manufacturing enterprise in India in the energy-related and infrastructure sector which includes Power, Railways, Telecom, Transmission and Distribution, Oil and Gas sectors and many more with global credentials. BHEL was established more than 50 years ago, ushering in the indigenous Heavy Electrical Equipment industry. Today it ranks among the leading power Equipment Manufacturers in the world. Set up in mid-fifties, BHEL has diversified its products base over the years and today BHEL caters to the need of all key sectors of the economy.
BHEL‘s products cater to the wide spectrum of customers in various fields like power generation & transmission, oil exploration & ,transportation, steel & metals, fertilizers & petrochemicals, refineries, cement plant, heavy engineering industries, non-conventional energy sources, defense equipments, etc. More than 65% of the installed capacity for electrical power in India is contributed by BHEL. The wide network of BHEL‘s 14 manufacturing divisions, 8 service centers, 4 power sector regional centers, 18 regional offices and over 150 sites spread all over India & abroad enables the company to promptly serve its customers & provide them suitable products systems and services at competitive rates. BHEL manufactures almost all high technology products required for power sectors viz. Steam Turbines, Gas Turbines, Nuclear turbines, Generators, Boilers, Heat Recovery System Generators, Pump & Compressors, Heat Exchangers, and Control Instrumentation etc. BHEL has carried out ‘System Engineering’ and ‘Turnkey Execution’ of projects involving coal, liquid & gas based power plants not only In India but also in countries like Malta, Cyprus, Malaysia, Saudi Arabia, man, Libya etc. BHEL‘s technology for products/systems is at par with the latest/best in the world. BHEL has collaborated with leading companies in world like M/s Siemens, Germany; M/s General Electric, USA M/s Alston, France, etc.
Main Facilities of manufacturing and Testings
As an engineering conglomerate, BHEL offers over a wide spectrum of products and services for core sectors including power generation, transmission and distribution; transportation; and oil and gas. As well as the supply of non-conventional energy systems. BHEL Hardwar plant is equipped with most modern and sophisticated machine tools.
Various Products
Pulverizes, valves, oil field equipments, heat exchangers, transformers, locomotives, steam generators, gas turbines, steam turbines, hydro turbines, pumps, motors, generators, circuit breakers, heat recovery steam generators, battery operated vehicles, air preheater, wind mill, fan, soot blowers, pressure vessels, electrostatic precipitators, boiler drum, super heater, water wall panel, boiler drum,
Heat recovery vehicles, armed recovery vehicles, re-heaters, super rapid gun mount.
Besides manufacturing these products, BHEL also takes up the onsite erection, commissioning and testing of these equipments. By the end of 2009, it will have a total capacity of 15,000 MW.
INTRODUCTION OF EXCHANGE
A telephone exchange is often also called a telephone switch. Originally, the telephone exchange was created as a means of a provider receiving and inbound phone signal, interacting with a subscriber and then switching the signal to whomever the subscriber wished to speak with. This was referred to early on in the history of telephony as exchanging a call.
The first hints of the automatic switching to come came in 1891, with the creation of the stepping switch. A stepping switch allowed for the first real automation, which involved being able to reach subscribers in the immediate area by using a telephone dial to signal a four number sequence. This allowed the phone exchange operators to focus on exchanging inbound and outbound signals that needed to be processed outside a local calling area. However, the stepping switch helped with the designation of the terminating number, as the caller could ask the operator to
Frequencies used in Telephony
The numbers from 1 to 5 falls in low band and 6 to 9, 0 falls in high band. Till the handset is on-hook, the ringing section of the apparatus is on through telephone line but on lifting the handset the ringing section become off, also the dialing and speech section becomes ready. On lifting the handset first the dial tone is received which is amplified by the amplifier of speech section. When a number is pressed on the keyboard, the dialing pulses are made on and off according to the number dialed. For example if 5 is pressed then dialing pulses are made on and off 5 times. This process can be heard on the receiver. There is a gap of 1 sec. between consecutively pressed numbers. When the handset is placed on or is lifted from the instrument a switch is operated called the hook switch. The main function of this switch is to toggle between telephone-line and ringer, dialing & speech sections of the telephone. When the handset is on the telephone then ringer section of the telephone is on while on lifting it ringer section is disconnected and dialing section is connected.