中性点接地电阻柜的电气特点 |
添加时间:2018/1/16 14:35:09 浏览次数: |
1、耗能元件,是电网对地电容中能量(电荷)的泄放通道,又是系统谐振的阻尼元件。 2、单相故障时,非故障相稳态电压比采用中性点不接地或消弧方式的稳态电压升高稍低。 3、由于显著的阻尼作用,可消除由于各种原因引起的系统谐振过电压(如:铁磁、高频、分频、断线、线性谐振等)。 4、有效限制单相故障时的过电压倍数,原因: a 故障点电流较大,能形成稳定电弧,不易产生电弧熄灭又重燃现象。 b 本身为耗能元件,可消耗系统对地电容中存储的能量。 c 在息弧的时间内(半个周期),通过电阻将系统对地电容泄放掉,降低中性点电位,每次电弧重燃时,都和第一次建弧的初始条件相似,不会形成很高的电弧重燃过电压倍数。 5、与线路零序保护配合,可准确判断出故障线路并迅速切除,这一特点避免了为寻找接地故障进行的大量拉合闸操作而产生过电压。此特点适用于电缆线路为主的城市配网。但以架空线为主的配电网单相接地而引起的跳闸次数将大大增加。 6、故障由于及时切除电源,可大大减少发生人身安全事故的机会。
1. The energy dissipation element is the discharge channel of the energy (charge) in the ground capacitance, and it is also the damping element of the system resonance. 2, the steady state voltage of the non fault phase is slightly lower than that of neutral point ungrounded or arc suppression. 3, due to the obvious damping effect, it can eliminate the system resonance overvoltage caused by various reasons, such as ferromagnetism, high frequency, frequency division, disconnection, linear resonance, etc. 4, effectively limit the overvoltage multiplier of single phase fault. The reason is that the a fault point current is large, it can form stable arc, and it is not easy to produce arc quenching and reburning phenomenon. B itself is an energy dissipating element that consumes the energy stored in the ground capacitance of the system. In the time of C arcing (half cycle), the capacitance of the system is released by resistance, which reduces the neutral point potential. When the arc reignited, it is similar to the initial condition of the first arc, and does not form a high arc reburning overvoltage multiplier. 5, in line with line zero sequence protection, it can accurately identify the fault line and quickly remove it, which avoids overvoltage in order to find a lot of pull in operation for grounding fault. This feature is suitable for urban distribution network based on cable lines. But the trip frequency of single-phase grounding in overhead line mainly caused will greatly increase. 6. Due to the timely removal of the power supply, the chances of personal safety accidents can be greatly reduced. |
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