结合上海电网具有短路容量大、电气距离短的特点，提出了使用进口仪器测试工频变化量距离保护的具体方法。
For Shanghai power grid, which has large short circuit capacity and short electrical distance, a method using imported instrument to test power frequency variation distance protection is presented.
国产继电保护试验仪一般都有针对工频变化量的专用测试菜单，而进口仪器则需预先计算和设置。
The appropriative test menu for "power frequency variation" is normally built in domestic relay protection test instruments, but it should be calculated and set beforehand for imported instruments.
从微机工频变化量距离保护两种试验方法和试验结果之间的矛盾入手，在分析其原理的基础上，以实例分析和讨论这两种方法，指出了保护本身的不足之处。
The shortcomings of the protection itself is pointed out through analysis of examples and discussion on these two methods for microcomputer based power frequency variable distance protection.
文章系统分析了“工频变化量”技术的理论基础和在各种保护装置中的实际应用，并总结了这些保护装置的独特优势。
The paper systematically analyzed theory basis of DPFC technology and its application in all kinds of protection devices, and then summed up the unique advantages of these devices.
文章系统分析了“工频变化量”技术的理论基础和在各种保护装置中的实际应用，并总结了这些保护装置的独特优势。
The paper systematically analyzed theory basis of DPFC technology and its application in all kinds of protection devices, and then summed up the unique advantages of these devices.
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