Motors cable selection

When located at the motor the capacitor bank will be normally cabled from the motor terminal box, so that the size of the motor cable can then be selected on the basis of the reduced-power factor corrected current drawn by... 

Table 12.4 Selection table for switches, fuses, relays and cables for different sizes of LT motors...

Consider a 55 kW motor to be switched direct on-line and instalied, say, at 75 m from its controlgear. To select the most appropriate cable size refer to Table 12.4, where... 

The motor cost is but one facet of any cost study for selecting voluigc level. The study must compare installed cost of motor, starting equipment, transformers, and power and control cables at the various levels under consideration, as well as plant standards. 

MG 2 Safety Standard for Construction and Guide for Selection, Installation, and Use of Electric Motors and Generators MG 10 Energy Guide for Selection and Use of Polyphase Motors VE 1 Cable Tray Systems... 

Cables are used to supply power to individual loads such as motors, and to groups of loads as in the case of a feeder to a switchboard. Selecting the load current for the first case is reasonably simple. Most individual loads have a manufacturer s nameplate that gives details such as rated power, voltage, current and power factor. If the current is not given on the plate then it should be calculated from the output power, power factor and efficiency of the load. 

Industrial applications include pipe seals, hydraulic system seals, dampers for machinery and high speed printers, and motor lead wire insulation. The fact that the polymer contains no halogens along with certain unique compoimding techniques for flame resistance prompts the selection of ethylene-acrylic as jacketing material on certain transportation/military electrical cables, and in floor tiles. 

Where motor operated valves (MOVs) or air operated valves (AOVs) are selected as ESDVs, they should, as a minimum, have backup activation power sources, and the utility service lines should be highly reliable and protected. It should noted that full motor operated and air operated ESDVs are not the same as fail safe spring return valves, even if frequent functional testing is undertaken. The reliability of an internal spring return actuator is considered better than a self-contained MOV or AOV with its own local power source and protection of cabling. This is because additional components of a MOV or AOV contribute to additional failure points and will also have a higher level or vulnerability from external events than an internal spring mechanism. 

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