
Energy and Power Engineering, 2013, 5, 1221-1225
doi:10.4236/epe.2013.54B231 Published Online July 2013 (http://www.scirp.org/journal/epe)
Experimental Study on the Cyclic Ampacity and Its
Factor of 10 kV XLPE C able
Xiaoliang Zhuang, Haiqing Niu, Junfeng Wang, Yong You, Guanghui Sun
School of Electric Power, South China University of Technology, Guangzhou, China
Foshan Power Bureau of Guangdong Power Grid Company, Foshan, China
Email: xl.zhuang@163.com
Received April, 2013
ABSTRACT
The load varies periodically, b ut the peak current of power cable is controlled by its continuous ampacity in China, re-
sulting in the highest condu ctor temperature is much lower than 90 ℃, the permitted long-term working temperature of
XLPE. If the cable load is controlled by its cyclic ampacit y, the cable transmission capacity could be used sufficiently.
To study the 10 kV XLPE cable cyclic ampacity and its factor, a three-core cable cyclic ampacity calculation software
is developed and the cyclic ampacity experiments of direct buried cable are undertaken in this paper. Experiments and
research shows that the software calculation is correct and the circuit numbers and daily load factor have an important
impact on the cyclic ampacity factor. The cyclic ampacity factor of 0.7 daily load factor is 1.20, which means the peak
current is the 1.2 times of continuous ampacity. If the con tinuous ampacity is instead by the cyclic ampacity to control
the cable load, the transmission capacity of the cable can be improved greatly without additional investment.
Keywords: XLPE Cable; Experiment; Cyclic Ampacity; Software
1. Introduction
Power cable has been widely used in urban power grids.
With the rapid economic development in China, the
transmission capacity of power cable needs to be im-
proved. However, it is extremely difficult to construct
new cables due to the high cost and the dense under-
ground pipeline in urban [1]. Therefore, it is very impor-
tant to take full advantage of the cable capacity.
In China, the cable load is ad justed based on its rating,
i.e. the continuou s ampacity. However, the actual current
in operation cable is not continuous but showing a peri-
odical variation. What’s more, the daily load curve shape
doesn’t change a lot within a relatively long period of
time (such as one month). Due to the existence of ther-
mal capacity of cable system (including the cable and its
surrounding soil), the cable conductor temperature (namely
insulation temperature) is delayed hours after the load
changes, the delay time depend on its thermal time con-
stant. In this situation, if the cable peak current is con-
trolled by its continuous ampacity, the highest cable
conductor temperature will be much lower than 90℃,
which is the permitted long-term working temperature of
XLPE, resulting in a waste of the current carrying capac-
ity. If using the cyclic ampacity to control the cable load ,
its transmission capacity can be improved greatly without
any additional investment [2].
IEC 60853 standards have given the calculation meth-
ods of the cable cyclic ampacity factor and the cyclic
ampacity [3,4], with condition that the conductor tem-
perature will up to but not exceeding the maximum al-
lowable cable insulation working temperature. In order to
bring the transmission capacity of 10kV distributed cable
lines into full apply, a three-core cable cyclic ampacity
calculation software is developed and the cyclic ampacity
experiments of direct buried cable are undertaken in this
paper, and also the software calculations are used to do
theoretical research. There are few articles about the cy-
clic in domestic now, but these experiments can provide
some experiences and references for future related re-
searches.
2. Experimental Study Content
2.1. Test Object and Ground
Experiments are undertaken in Foshan experiment field,
shown in Figure 1(a). Cables are located in the cement
tanks box filled with sand, which is buried in the soil,
shown in Figure 1(b). The depth of cable is 700 mm, the
length of cable is 20 m and the cable is YJV22-8.7/ 15-3
× 240.
2.2. Selection of Daily Load Curve
According to Foshan residential, industrial, commercial
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