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三相电动机，其铭牌数据如下：PN=50kW，cosαN=0.8，ISt=2.6IN，UN=380V，设系统三相短路电流为5.3kA，环境温度为25℃。要求：
(1)若采用VV电缆，选择其截面。
(2)为该电动机选DW15型低压断路器。

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The University of Newcastle offers international students the perfect combination of lifestyle. and learning.
Set in excellent bush-land just minutes away remarkable beaches, waterways and forests, both campuses of the University are well known for their academic(学术的) excellence and innovative(革新的) teaching. Not surprisingly, its graduates are in high demand.
The University of Newcastle attracts students and staff of the highest quality. Today more than 17,000 students study in one of 150 undergraduate and postgraduate courses offered by 11 faculties: Architecture; Art and Design; Arts and Social Science; Economics and Commerce; Education; Engineering; Law; Medicine and Health Sciences; Music; Nursing; and Science and Mathematics.
The University has two campuses: Callaghan(the largest campus) in Newcastle, and Central Coast at Ourimbah(halfway between Newcastle and Sydney), which supplies a growing region with its educational needs.
The University is also known worldwide for its problem-based learning programs. Used mainly in the Faculties of Medicine and Health Sciences, Nursing and Architecture, problem-based learning places students in small groups where they solve problems they are likely to face in their working lives. In other words, it gives a clearer purpose to learning.
The University of Newcastle
Location of the University: beautiful【46】surrounded by beaches, waterways and forests.
Total number of students: over【47】.
Number of the courses offered at the University:【48】.
The names of the two campuses:【49】.
Special characteristics of the University:【50】.

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某公司按CIF LONDON向英国出口一批季节性较强的货物，双方在合同中规定：买方须于5月底前将信用证开到，卖方保证运货船只不得迟于8月30日抵达目的港，如货轮迟于8月30日抵达目的港，买方有权取消合同。如货款已收，卖方须将货款退还买方。问这一条款是否合理？为什么？