过电压起因
Overvoltage cause
电力系统中电路状态和电磁状态的突然变化是产生过电压的根本原因。过电压分为外过电压和内过电压两大类。研究电力系统中各种过电压的起因，预测其幅值，并采取措施加以限制，是确定电力系统绝缘配合的前提，对于电工设备制造和电力系统运行都具有重要意义。
The sudden change of circuit state and electromagnetic state is the fundamental cause of overvoltage in power system. Overvoltage is divided into two categories: external overvoltage and internal overvoltage. Studying the causes of various overvoltages in power systems, predicting their amplitudes and taking measures to limit them are the prerequisites for determining the insulation coordination of power systems, which are of great significance to the manufacture of electrical equipment and the operation of power systems.
无论外过电压还是内过电压，都受许多随机因素的影响，需要结合电力系统具体条件，通过计算、模拟以及现场实测等多种途径取得数据，用概率统计方法进行过电压预测。
Both external and internal overvoltages are affected by many random factors. It is necessary to obtain data through calculation, simulation and field measurement in combination with the specific conditions of the power system, and to predict the overvoltage by probability and statistics method.
针对过电压的起因，电力系统必须采取防护措施以限制过电压幅值。如安装避雷线、避雷器、电抗器，开关触头加并联电阻等，以合理实施绝缘配合，确保电力系统安全运行。
In view of the cause of overvoltage, power system must take protective measures to limit the amplitude of overvoltage. Such as installing lightning arrester, lightning arrester, reactor, switch contacts with parallel resistance, etc., to reasonably implement insulation coordination to ensure the safe operation of the power system.