SPECIALISED ENGINEERING GROUNDING BRUSHES

The brushes are exclusively developed for arresting stray currents developed in compressor and turbine trains used in refineries, fertiliser companies etc. Turbine shaft of capitive power plants rotates at very high speed to compress gases at refinieries,power generation. The turbines experience an electrostatic charge and stray current generated, passes through the bearings where the least resist path causing sparks unless properly grounded. Spark erosion on bearings, seals or other components damages heavily and may result forced shutdown. The erosion of the bearings, thrust pads can be avoided by giving an electrical conducting medium as an alternative path to take the current and ground to earth before passing to the bearings.

ADVANTAGES OF METALLIC GROUNDING BRUSH:

Multiple bristles have advantage over solid block(carbon) as it covers more contact area while sliding over rotors and as a result better grounding. A magnified view of surface, ideally clean, will appear as shown in Fig. 1 – 1. In visualizing this surface, please notice that the vertical magnification is ten times that the horizontal. This means that the actual slops on the hells and the valleys are more gradual than pictured.

Such bristles also helpful in drawing micro currents and voltages which normally passes to the rotor due to the higher activation energy area. Stray voltages occur on rotating shafts in magnitudes ranging from micro-volts, to hundreds of volts. The former may be generated from shaft rotation in the earth’s magnetic field, or induced from electromagnetic communication signal induction. The latter can be induced by shaft rotation linking asymmetric magnetism of electrical machinery, by residual magnetism present in a shaft or in adjacent stationary members and by induction from switching of power electronics, exciters and/or current-carrying brushes. Shaft voltages can be either “friend” or “foe”. As “friend”, they can warn, at an early stage, of problem development long before the problem is apparent on traditional monitors and instruments. As “foe”, they can, as a minimum, generate circulating currents, reducing unit efficiency and, as a maximum, the generated current can damage bearings, seals, gears and couplings, often forcing unit shutdown. Control of shaft voltages can minimize the potential for damage. This control can be either passive, by simply placing grounding brushes, or active by injecting counteracting current signals onto the rotor. In both cases strategic brush placement and consideration is essential to satisfactory shaft grounding and signal sensing. Very important to the success of shaft grounding and signal sensing is the choice and reliability of plant grounding. MCUBE provides high performance, high reliability bristle type fiber brushes for use in shaft grounding (shaft earthing) of all types of stray electrical shaft currents. The brushes can also be used for instrument signal transmission and generator or electric motor on-line diagnostic work. Installable and serviceable during operation. For damage prevention by measuring and grounding stray currents of any origin in: Turbines, Compressors, Generators, Motors, Gears, Ship Propeller Shafts, or other rotating equipment. Because no maintenance or cleaning is usually necessary, the fiber brushes are especially useful in radiation control areas. Failure to properly ground rotating shafts can result in unexpected outages and expensive damage, such as bearing failure due to spark erosion (sometimes called electrolysis). Catastrophic wrecks are a possibility. Technical papers on this subject are available. In addition to their use as shaft grounding brushes (earthing brushes), the brushes are also suitable for the transmission of instrument signals from a rotor without the use of special slip rings. This allows continuous monitoring of parameters such as voltage, vibration and torque during normal field operation.

We offer a complete need based engineering solution for arresting stray currents in new/old turbine-compressors train by providing customised metallic brushes.

Range of Products: We supply consumable engineering metallic brushes (Spares) for ratings upto 1MW-120MW

OUR CUSTOMERS:BHELR&D HYDERABAD ,VARAM POWER LIMITED SRIKAKULAM TO NAME A FEW

Variants Offered: A-1, A-2,B-2,B-3

• A-1 Variant is suitable for Electrical motor application
• A-2 Variant is suitable for 2-10MW Steam turbine-Compressor turbine train
• B-2 Variant is suitable for 10-50MW Steam turbine-Compressor turbine train
• B-3 Variant is suitable for 50MW+ Steam turbine-Compressor/Steam turbine