Assam Carbon Products Limited Nehru Place, Delhi

DC traction systems have inherent differences to their industrial counterparts having to cope with increased levels of vibration and thermal shock as a result of rapidly changing load currents. The advent of fast switching thyristor control and regenerative braking have added to the harsh conditions already experienced by the carbon brush which is a vital part of the current carrying chain, so it is imperative that the correct grade of brush is chosen to optimize the performance and reliability of the equipment. Traction applications may be divided into three categories: 1. On pure electric systems: ventilator motors, lighting alternators or generators, motor alternatorgenerator sets. 2. On diesel electric systems: main and auxiliary generators. (Often replaced by brushless alternators with diode rectifiers). 3. Traction motors: traction motors are generally quite different from industrial motors. In order to obtain the required torquespeed characteristic, they are almost always series wound motors. This gives a fairly constant powder output over the speed range, with torque declining as speed rises. Thus, on starting, the high armature current gives a high field current, which provides the torque needed to accelerate the locomotive from rest. As the speed increases so does the back emf; thus the current falls, the field weakens and the speed rises further.

Steam heated rolls are used in the production process of many industries like Paper making, Petrochemical, Plastics, Rubber and Textile etc. One of the most common application is in paper making where the wet paper supported on felt passes over a steam-heated drying roll.

Steam heated rolls are used in the production process of many industries like Paper making, Petrochemical, Plastics, Rubber and Textile etc. One of the most common application is in paper making where the wet paper supported on felt passes over a steam-heated drying roll.

Silver Impregnated Graphite (SIG) contacts are used in high safety applications of railway signaling, traffic signaling, and numerous other applications due to high silver content that eliminates the risk of welding in the presence of graphite. High contact resistance (>200mΩ) was observed in the SIG contacts in a railway signaling operation after a few thousand operations of the relay. The high contact resistance was discovered to be a result of loose dustforeign particles residing between the two contacts. Silver had been preferentially removed from the contacting surfaces during switching operations by an abrading effect of the dustforeign particles, leaving only graphite on the contact area. Wear was accentuated by the presence of porosity and low hardness of the contacts, leading to improper interaction between the mating surfaces.

Assam Carbon Axial Brearings are made in the range of carbon materials (Carbon Graphite resin-impregnated or metal-impregnated) to meet different application requirements.All Carbon grades retain the basic properties, thus making them as unique engineering material, and particularly suited for axial bearings which may operate in conditions beyong the limits of other material.. Carbon Axial Bearing works better than LTB Bearing commonly used in submersible motor. Low coefficient of friction improves the overall efficiency and lower the starting current. Better machining tolerances can be achieved in carbon. Taking into consideration the worldwide ban on the production and use of lead, it is advisable that carbon bearings should be used in-place of LTB for even better performance. Key Features of Axial Bearing: Helps the pump to run in dry conditions. Low heat generation. Contribute in conservation of power. Withstanding of unpredictable load. Reduced input power requirement compared to Ferro Asbestos. No seizure of motor after prolonged rest. Low maintenance cost. Lower HP pump performance at par with higher HP pump. Start up at 90 volts compared to 120 volts for Ferro Asbestos. Improving pump efficienct by minimum of 5%.

Linear current collection is similar to carbon brush collection except that in linear collection the collector is moving rather than the conductor. Current collectors have relative motion along a line instead of around a rotating cylinder; point or line contact is present, as opposed to the area contact of a brush. There is more frequent and more complete rupture of contact with the consequence of sparking and arcing. In addition, linear current collectors are more likely to operate outdoors, subject to the variations of environment and weather. In order to cope with these disadvantages, collector materials have to be much harder, denser and more abrasive than brush materials.

Steam heated rolls are used in the production process of many industries like Paper making, Petrochemical, Plastics, Rubber and Textile etc. One of the most common application is in paper making where the wet paper supported on felt passes over a steam-heated drying roll. The most efficient way to connect the steam supply to the rotating unit is a by means of a steam nozzle using Carbon sealing rings, which have a high degree of reliability and maintainability. Carbon is self-lubricating and has excellent resistance to wear; it beds in rapidly and does not wear or score the counter faces. Carbon has high mechanical strength under compression and maintains its properties at high temperatures. Although, theoretically it is possible to use sealing rings of rectangular cross section but, in practice it would be extremely difficult to obtain proper alignment. That is why a self-aligning spherical construction is adopted. It is, of course, essential that all sealing surfaces are highly finished; and also, sufficient clearance must be provided at the bores to allow the rings to float freely. Assam Carbon Products Ltd. have been manufacturing Steam nozzle joint rings and bearings for many years in collaboration with Ms. Morganite Special Carbons Ltd., U.K. These are manufactured in grades for operating temperature up to 3500°C. Specially for high pressure steam joints our metal impregnated Antimony class grade is recommended.

Carbon sealing rings are used as the wear face of most mechanical seals for the sealing of fluids in all industries. APPLICATIONS ARE : Process pumps Rotary steam joints Seals for agitators and autoclaves Chemical pumps Cold and warm water pumps Corrosive liquid pumps.

Steam heated rolls are used in the production process of many industries like Paper making, Petrochemical, Plastics, Rubber and Textile etc. One of the most common application is in paper making where the wet paper supported on felt passes over a steam-heated drying roll.

Graphite heating elements in all standard diameters and lengths to suit the plant converned, supplied with matching precision-machined graphite contacts. • For high-performance operation in vacuum steel degassing plants for hydrogen degassing, deoxidation, decarburization and alloying. • For melting metals and holding them at high temperatures.

Since the end of World War II, the chronic requirement for power and yet more power has become a problem of international rather than purely national interest. Throughout the world, the increasing tempo of industrialization and the general improvements in living standards have created a situation that can only be countered by bold, far-sighted planning and adventurous engineering. Hence, the now-familiar emphasis on nuclear power stations and hydro-electric schemes. Carbon and its numerous applications in nuclear engineering will no doubt be a subject in some future edition of this publication. This article is concerned with the part carbon-graphitic glands play in the running of that essential Io a nation’s industrial and domestic power needs - the hydro-electric power station.To date, nobody has discovered, produced or invented a material for turbine glands that can better carbon. For this reason, carbon is widely employed in this capacity, except in one or two countries like Italy and the U.S.A. where soft packing glands arc preferred. Carbon glands arc reliable. can be easily fitted in comparison to other types. do not need frequent adjustments. and, very important, do not damage or wear the turbine shaft. The glands manufactured by Assam Carbon Products Limited are highly-specialized products developed in association and collaboration with prominent turbine constructors throughout the world. They have won for the Company a substantial percentage of the world’s markets for such equipment. So far, glands have been supplied for shaft diameters up to 1170 mm. It is hoped, however. that the Company will shortly embark upon a contract for the largest. Most ambitious hydro-electric scheme in the world, where shafts of 1350 mm diameter will have to be sealed.

Semifinished products in cylindrical and rectangular formats with specific property combinations. • Ready-made dies, precision-machined with optimum surface finish, for the continuous casting of precious metals.

Assam Carbon vanes are made in the range of carbon materials (carbon graphite, metal-impregnated carbon graphite and resin-impregnated graphite) to meet many different application requirements. All Assam Carbon grades retain the basic properties which make Carbon unique as an engineering material and particularly suited for vanes which may operate in conditions beyond the limits of other materials. Self-Lubricating Carbon vanes are self-lubricating and therefore, ideal for pumps, handling liquids such as petrol which has poor lubricating properties. They can also operate in unlubricated compressors to deliver air or gas uncontaminated by lubricating oil or grease, in which case Carbon gives a fine polish to the cylinder wall which reduces the wear rate of the vane after bedding almost negligible proportions

Carbon Bearings have been developed by Assam Carbon Products Limited over the last 30 years. The generic term “Carbon Bearings” includes all possible variations of the basic material “Carbon”. Therefore it covers “carbon-graphite”, “metal-graphite” and “electro graphite”. Carbon is self-lubricating and has a low coefficient of friction at high and low temperatures. Its use as a bearing material is extensive when a conventional lubricant is not possible and also where the performance of other lubrication is poor. There are other properties which give it unique and distinctive advantages for bearings.

The use of variable – speed drives with AC motors induces electrical currents on the motor shaft. Once they exceed the resistance of the bearing lubricant, these currents discharge to ground (typically the motor housing), causing fusion craters in the bearings. Over time, these craters increase in size and number, resulting in frosting, pitting, fluting and eventually bearing failure. This type of premature bearing failure can cost thousands of dollars in increased maintenance and lost production.