2014年6月11日星期三

Introduce of the voltage classes

The voltage of power is classified into different types. The low voltage , medium voltage and high voltage. What is the rated voltage of power cable?  The rated voltage is normal voltage electric power system and equipment requirements.
Firstly, Uo is the AC rated voltage(effective value)of metal screen,  metal armor and metal sheath of conductor used in power cable design.  The insulation structure design of cable and electric test all adopt Uo as the standard.  It reflects the insulation level of power cable.
Secondly, U is the AC rated voltage(effective value)of phase conductor in power cable design.  It is not only related to insulation level of power cable,  but also to system earthing style and power cable category in using power cable.
At last, Um is the maximum value of the highest system voltageto be borne by equipment.
The rated voltage of the cable for a given application shall be suitable for the operating conditions in the system im which the cable is used, and is expressed in the form of U./U(Um)KV. Where:
U.-The rated power-frequency voltage between conductors and screen or metallic-sheath,for which the cable designed;
U-The rated power-frequency voltage between conductors,for which the cable designed;
Um-The maximum value of the "highest system voltage"for which the equipment may be operated.
Visit www.qscable.com and www.huadongcable.com to learn more wire and cable information.

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