Area classification, motors

The compressor or blower installation in a typical refinery or chemical process unit is not out-of-doors completely. Some form of shelter often is provided, ranging from only a roof to a completely closed building. When process equipment such as a centrifugal gas compressor, which is not hazardous in normal operation, is present in the shelter, the hazard classification depends on the extent to that which the shelter restricts ventilation. The extent of the shelter provided determines the area classification and the type of motor enclosure that should be applied. 

After an area classification has been established, then anelectrical equipment, instruments, and wiring must adhere to that classification. Therefore, some motor enclosure types would not be electrically acceptable for specific area classifications. 

If the pumps are located indoors, a Division 1 classification is likely to apply. Motors must be Class 1, group D, explosion-proof, or they may be separately ventilated with clean outside air brought to the motor by fans. Auxiliary devices such as alarm contacts on the motor must be suitable for the area classification. The installed costs, overall efficiencies, and service factors associated with the enclosures that are available will influence the selection. 

Motors, electrical components, and electrical installations shall be suitable for the area classification (class, group, division, or zone) specified by the purchaser and shall meet the requirements of local codes (such as NFPA 70, Articles 500,501, and 502) specified by the purchaser. 

Electrical cable schedule Voltage drop calculations Electrical area classification Electrical instrument interface drawings Underground electrical cable and cable trench arrangement Electrical equipment layout drawings Motor control center and power layout Load and short-circuit analysis VSDs configuration Plant lighting plan... 

For Case 2, each DVP requires 72.66 kWh of electricity, and operating cost savings due to this modification are US 257 801/year. Installed cost of two DVPs, based on vendor quotation, is US 400 000. So, payback period for this retrofit modification is 1.6 years. Thus, replacing the existing SJEs by DVPs is attractive for low capacities and non-hazardous applications such as a steam turbine s surface condenser vacuum system. DVPs are efficient, they require less electricity and so modification required at the substation is minimal. They are very compact and can be installed at ground level or on elevated platforms. Depending on the area classification of their location, explosion-proof motors may be required. 

The efficiency is set by the pump manufacturer when the final pump selection is made. It is usually based on their shop tests for the same model and size pumps. The pump efficiency can vary between 10% and 80%. Pump electric motor specifications require mechanical and electrical requirements. Motors can vary in size depending upon power, speed (RPM), frame size, area classification, orientation, service factor and type of enclosure (e.g. totally enclosed fan closure). 

Pumps are essential to the successful operation of a solvent storage tank. All pumps should be located in open areas outside the bunds, on an impervious base, such as concrete, and at least 4 m from buildings, boundaries and sources of ignition. Clearly the characteristics of the motor must match the flash point of the solvent and the area classification operating at the point of location. 

Second, the discussions will be focused mainly on instrumentation and control parts. The specifics concerning other electrical equipment such as motors, etc. will not be covered unless called for as part of instrumentation discussions. In general, the guiding factors for EAC, hence hazardous area classification, shall include but not be limited to the following ... 

Electrical engineering 1116 plot plan is used to produce area classification drawings, to locate switchgear and the incoming sut tation and motor control center, to route cables, and to estimate bulk mato ials. 

Except for areas with fire or explosion hazards (hazardous areas), motor enclosures are designed to provide protection to the internal working parts. The development or improved insiilating materials and finishes has affec ted the required degree of protection and consequently the design and classification of enclosures. Examples of several types of enclosures are shown in Fig. 29-4. 

The selection of the motor enclosure type involves not only economics but also assessment of two factors area hazard classification and other area operation conditions. 

In Division 1 areas, motors and generators must be either explosion-proof or approv ed for the classification by meeting specific requirements for a special ventilation system, inert gas-filled construction, or a special submerged unit. Although explosion-proof motors are expensive, they normally are available. Explosion-proof generators normally are not available. 

What electrical classification would be specified for an area that has Classes I and II, Groups A and E, and Divisions 1 and 2 motors ... 

Beginning with Kraepelin s (1921) systematic classification of dysphoric mania, considerable attention has been paid to mixed states of bipolar disorder. Kraepelin s model was based on variable symptom patterns expressed in three areas, mood, thought, and motor activity. Once considered to be uncommon, current estimates suggest that the prevalence rate for dysphoric, or mixed mania, is approximately 30 percent (McElroy et al. 1992). Debate continues regarding the status of mixed mania as a distinct affective state versus a form, or stage, of typical mania. However, there is convincing evidence to support the opinion that mixed episodes can be more severe, chronic, and difficult to treat than pure manic or depressive episodes (Clothier,... 

The Detroit Public Library also cooperates in the plan and has as its responsibility the acquisition of foreign literature on the Engineering and Technology of Motor Vehicles and Cycles, again with certain minor exceptions. This area is included in the Library of Congress Classification Numbers (TL 1-499). 

The most widespread classification by operational properties and areas of application of motor oils is the API classification (Table 1.7). 

Table 1.8 CCMC classification for motor oils by its operational properties and areas of application. ...

Among the ANSI standards is the National Electrical Code (NEC) which is directed at the elimination or control of electrical hazards. It defines the classification of areas according to the degree of hazard possibly foimd in the atmosphere and prescribes wiring methods, grounding, control, etc. These factors are important in motor selection. The NEC is a product of the National Fire Protection Association (NFPA). 

We should calculate the power spectrum density for selected electrodes above sensory-motor and parietal areas in both hemispheres (usually C3, C4, P3, and P4) which can be done using different methods such as combination of fast Eourier transform combined with Hanning cosine window for selecting the EEG signals. There are several methods of processing and classifications of signals which should be studied in order to achieve the optimum method [10], Based on the studied patterns the proper feedback commands are... 

The most severe effect of iodine deficiency is cretinism, which is rare in areas of mildly endemic deficiency but may have reached 5-10% or more in areas with severe deficiency. There are general classifications of cretinism, the symptoms of which frequently overlap. Neurological cretinism presents as extreme mental retardation, deaf-mutism, and impaired motor function including spastic gait. 

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