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Showing posts from July, 2015

Cable Pulling Procedure and Following Conditions in Field

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Cable Pulling Procedure and Following Conditions in Field
Cable pulling procedure and following conditions in the field during cable pulling time is alternately referred as what the cable pulling rightprocedure is?; and what conditions should be followed?, in field level during cable lay due to safe cable pulling. Cable manufacturer have handbooks or cable catalogue that describe the methods of safe cable pulling procedure and conditions.
This article not described details theoretical and mathematical calculation; just tried to make sense basic knowledge for workforce related to cable pulling in field level to pull cable perfectly and safely as well as understand why should follow the cable pulling conditions. Keywords: Discussed keywords in this article are History of Cable InstallationMaximum Allowable Pulling Tension on Conductors, Pulling Tension Calculations, Coefficient of Friction,Sidewall Bearing Pressure,Pulling Multiple Cables in a Duct or Conduit, Weight Correction Factors,P…

Why Purge System Is Required For Refrigerant and How Does It Operate in Chiller Compressor

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Why Purge System Is Required For Refrigerant and How Does It Operate in Chiller Compressor
Purge operation system for refrigerant in chiller compressor is carry-out to remove air and moisture; Low-pressure chillers typically include a purge system to remove air and moisture that may leak in, while minimizing the emission of refrigerant.
The purge consists of a small refrigeration system, a pump-out system, controls, and a filter drier. The purge’s refrigeration system includes a small compressor, a finned-tube air-cooled condensing coil, an expansion valve, and an evaporator coil inside of the purge tank. The tank with the evaporator coil separates condensable refrigerant from non-condensable air. Because the purge evaporator operates at a lower temperature and pressure than the chiller condenser, a mixture of refrigerant vapour and air is drawn from the chiller condenser, just above the level of the liquid refrigerant. (This is where air typically concentrates in a low-pressure chiller…

How Chiller Motor works for Long Time keeping Cool

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How Chiller Motor works for Long Time keeping Cool How chiller motor keeps cooling is an important issue because chiller normally works continuously and need to keep cooling; so how chiller motor keeps cooling. A motor is used to rotate the impeller(s). A direct-drive motor is connected directly to the impeller shaft and the impeller rotates at the same speed as the motor. A gear-drive motor transfers its energy to the impeller shaft using a set of gears. This allows the impeller to rotate at a higher speed than the motor. 
The direct-drive motor requires fewer bearings and does not incur gear losses. Additionally, since the compressor rotates at a lower speed, it can be much quieter.
Direct-drive compressors are, however, only practical in centrifugal chillers that use low-pressure refrigerants.
Another important difference in compressor motors is the issue of hermetic versus open. A hermetic motor is totally enclosed within the chiller’s refrigeration system. An open motor is mounted ex…

What Happen If Cables Placed In Magnetic Metal Conduit

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What Happen If Cables Placed In Magnetic Metal Conduit  Do we know what happen if cables in a magnetic metal conduit? Yes, at least we know that in any circumstances it should not be installed individual phase of an ac (alternating current) circuit in separate magnetic metal conduit. Most of us we follow these important rules for cable installation, but everyone can’t explain why we should follow this; what happen if individual ac phase placed in a separate metal conduit.

Yes of course, some of us are little advanced; we know we don’t place individual ac phase in metal conduit because of excessive heat may occur in that situation. 

Anyway, separate phases should not pass through magnetic structures because overheating can occur due to excessive hysteresis and eddy current losses.

Already question is arisen, is it acceptable to passes all the phases together through in a magnetic conduit? Yes, it is wise to passes through all the phases in any magnetic enclosure simultaneously so that maxi…

Conductor Stranding Perspective of Power Cable Construction

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Conductor StrandingPerspective of Power Cable ConstructionConductor stranding is major standpoint of cable construction that came long experienced in different circumstances. The problem for larger sizes of solid conductors is too rigid to installation in curvy area, jointing and termination work. The solution of these difficulties becomes from conductor stranding. The procedure of stranding is used depending on the metal temper and types. In general Copper conductor and Aluminum conductors are used for power cable construction. Normally Aluminum is softer than Copper, so solid Aluminum conductor using-limit is higher than Copper.

Key Words: Concentric Stranding, Compressed Stranding, Compact Stranding, Bunch Stranding, Rope Stranding, Sector Conductors, Segmental Conductors, Annular Conductors, Unilay Conductors.
Concentric Stranding:Concentric stranding is the typical choice for power cable conductors. In this construction procedure, there consists a  central wire and one or multiple l…

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