Norma Electrica internacional IEC 60287-1-1Full description
Descrição: IEC 60287-3-2
IEC 60287-3-2Full description
Norma Electrica internacional IEC 60287-1-1
Descrição: Norma Electrica internacional IEC 60287-1-1
IEC 60287-3-2
IEC 60287-3-2
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Descripción completa
hjj
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IEC 60287-1 electric cablesDescripción completa
Descrição: Norma
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Descripción: Norma
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Permissible current calculation
1. Introduction
While a current running through the conductor core, one is experiencing a heat generation by Joule effec heat passes the layer(s) of insulation to be evacuated to the exterior eventually. This heat evacuation occurs either : o By convection and radiation if the cable is on open air o By conduction if the cable is in contact with other items or material
When the generated heat equals to the heat evacuated in ambiant environment, we are experiencing a s balance characterised by a constant core temperature (steady state). This temperature should not exce maximum allowable temperature of the insulation to ensure to the cable an optimal lifetime.
The steady state maximum permissible current is the current value which, in a given environment, he conductor core to the maximum permissible value.
2. Permissible current calculation as per IEC 60287 o
IEC 60287 standard title
« Calculation of the continuous current rating of cables (100% load factor) » o
Scope
This standard deals solely with the condition of steady-state operation of cables at all alternating voltag direct voltages up to 5KV, buried directly in the ground, in ducts, troughs or in steel pipes, as well as ca air. The term steady-state is intended to mean a continuous constant current (100% load factor) just suffic produce asymptotically the maximum conductor temperature, the surrounding ambient conditions assumed constant. o
Basic hypothesis for permissible current calculation as per IEC 60287 o o o o o o o
Copper core Insulation class temperature “maximum allowable temperature value of t he insul Insulated cable on ladder supports or cleats cable in proximity) Sign(no up other to vote on this title Outer diameter of the cable not exceeding 150mm Useful Not useful radiation Cable in open air and protected from solar Continuous current up to 5 kV Decent heat disparsion and ventilation
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Permissible current calculation
3. Derating factors
o
Derating factors for several mono or multiconductor cables group
Arrangement of grouped cables
Derating factors Number of mono or multiconductor cables 4 5 6 7 8 9 12 16
1
2
3
1
0.8
0.7
1
0.85 0.79 0.75 0.73 0.72 0.72 0.71 0.7
Enclosed
Simple layer on walls or on floors or on not drilled tablets
