Maintenance insulation

Guide for insulation maintenance of large a.c. rotating machines (10 kVA and larger)... 

Percent of new insulation cost for annual insulation maintenance... 

J.L. Goudie, Silicones for outdoor insulator maintenance, in International Symposium on Electrical Insulation, 2002, Boston, Massachusetts, USA IEEE, p. 256-259. 

E.A. Cherney, R. Hackam, S.H. Kim, Porcelain insulator maintenance with RTV silicone rubber coatings, IEEE Transactions on Power Delivery, Vol. 6, No. 3, July 1991. 

PhenoHcs that are not heat-reactive may be incorporated into both air-dried and baked oleoresinous coatings. AppHcations vary widely and include clear and pigmented exterior varnishes, aluminum-maintenance paints, 2inc-rich primers, can coatings, insulation varnishes, and concrete paints. As modifiers in a great variety of appHcations, they enhance the performance of oleoresinous and alkyd coatings. 

Includes commercial and residential building, heavy con-stmction, maintenance, and insulating glass. ... 

Car manufacturers and intermediaries offer various forms of rail-car leases, ranging from short-term, full-maintenance rentals to long-term leases requiring outside financing (3). Many chemical shippers have substantial investments or lease commitments in tank cars and similar rail equipment, including cars constmcted of or lined with special materials for particular products. Other cars may be thermally insulated to prevent excessive heat buildup in transit or for protection against fire. 

Electrical heating is accomplished with resistance bauds or ribbons which must be electrically insulated from the machine body but in good thermal contact with it. The heaters must be carefully spaced to avoid a succession of hot and cold areas. Sometimes they are mounted in aluminum blocks shaped to conform to the container walls. Their effective temperature range is 150 to 500°C (about 300 to 930°F). Temperature control is precise, maintenance and supervision costs are low, and conversion of electrical energy to useful heat is almost 100 percent. The cost of electrical energy is usually large, however, and may be prohibitive. 

The maintenance of such motors at site is easy, since the stator can be wound with readymade PVC insulated winding coils, and does not need a varnish impregnation and subsequent baking etc., unlike a standard motor. It is thus easy to rewind them at site. 

By monitoring the insulation condition of the windings during maintenance, at least once a year, which can be carried out by measuring (a) the polarization index (Section 9.5.3) and (b) the dielectric loss factor, tan S (Section 9.6) and making up the insulation as in Section 9.5.2, when the condition of the insulation is acceptable and only its level is less than permissible. 

Insulating materials and their properties Ageing of insulation Practices of insulation systems Procedure for vacuum pressure impregnation Maintenance of insulation Monitoring the quality of insulation of HT formed coils during manufacturing... 

Installation of bearings and pulleys Important checks at the time of commissioning Maintenance of electric motors and their checks Maintenance of bearings General problems in electric motors and their remedy Winding temperature measurement at site Analysis of insulation failures of an HT motor at a thermal power station... 

The inverters are either voltage source or current source (see Figure 7-7a and b). There are other variations, but they apply to drivers smaller than the ones used with compressors. However, pulse-width-modulated (PWM) (see Figure 7-7c), transistorized units are less complicated and are relatively maintenance-free with reliable units available to at least 500 hp. For all but the smaller compressors, the current source inverter is the one typically used. With a six-step voltage source, a rule of thumb has been to size the motor at two-thirds of its rating so as not to exceed the insulation temperature rise. For current source motors, the output torque is not constant with decreased speed, which fortunately is compatible with most compressors, as torque tends to follow speed. For current source drives, one needs to upsize the motor captive transformer by approximately 15% to account for harmonic heating effects. 

Maintenance or cleaning of equipment Residues Loss of containment (breaking lines) Stripping insulation Burning-off paint, flame heating components Reaction or vaporization of cleaning products... 

Provision, use and maintenance of hygiene facilities for work with asbestos insulation and coatings Nitrosammes m synthetic metal cutting and gnndmg fluids (withdrawn)... 

The heaviest products obtained directly from oil arc lubricants, waxes, asphalt, and coke. These products have both domestic and industrial uses. Lubricants, for example, are applied in the operation and maintenance of industrial equipment and machinery. Asphalt, because it is not reactive to chemicals in the environment, is a superb material of construction in the building of roads and in roofing. It is also used in the waterproofing of concrete, the manufacture of black paints, and as a material lor tire threads, battery housing, electrical insulation, and other applications. The heaviest of all the petroleum products, coke, is used extensively as a major component of industrial electrodes and as a commercial fuel. 

To meet the 2001 U.S. energy standards and the 2003 phase-out of HCFCs, there is a great incentive to develop a significantly better thermal insulation. The most dramatic approach would use vacuum panels for insulating the cabinet. A number of U.S. and Japanese manufacturers have developed such panels and placed these kinds of refrigerators in homes. The panels consist of multilayer plastic envelopes filled with precipitated (fumed) silica. The claimed thermal conductivity is one-fourth that of polyurethane foam. The two major obstacles are cost and the maintenance of vacuum for twenty years. 

Note The upper figure is based on 1-in. insulation, the lower on 1V2 inch. This data is to be used for temperature maintenance only. Used by permission Engineering Data and Calculations, Part A, Sect. 11, p. 12, 1994. Thermon Manufacturing Co./Cellex Division. 

BS 5311, High voltage alternating current circuit breaker BS 6867, Code of Practice for maintenance of electrical switchgear for voltages above 36 kV BS 158, Insulating oil for transformers and switchgear BS 5622, Insulation co-ordination... 

Ideally, the walls should be of brick or concrete with an insulated roof. Large areas of glass should be avoided. It is desirable that all routine maintenance and operating functions can be carried out without having to open doorways. Openings and access to the boilerhouse should be away from sensitive areas. Free areas for air for both combustion and ventilation should be through acoustic louver... 

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