AC Transient [開閉サージ]

ここは我々は開閉サージ(Switching Surge) を勉強します。開閉サージと言えば, 私は経験があります。開閉サージは大切なテストになっていることを知りませんか? それは電圧レベルを生成することができます。それでは隔離を損じられるし損傷にはフラッシュオーバーになることができます。被害とフラッシュオーバーはよく電源システムに失敗に導きます。これは非常に、今日の業界では好ましくないです。 

じゃあ, この文章を読むことで,あなたが開閉サージの大切さを分かることを望みす。

The Switching Surge Defined

The switching surge comes in many different forms, and has many different sources. What is consistent between all switching surge events are:

1. They are low frequency events usually under a kilohertz and related to the fundamental power frequency.
2. They are always associated with a change in the operating state of the system.
3. They are always associated with a switching event on the power system.
4. They always involve trapped energy and its release.

Unlike the lightning surge, the switching surge is generally self induced by the operation of a breaker, switch or disconnect switch. However switching surges can be associated with lightning if during a lightning storm a lightning surge causes a breaker to operate and a switching surge is induced.

Figure 1 is an example of a typical switching surge. The wave shape is very complex. The amplitude of this switching surge is about 2.5 pu which is a quite common amplitude for switching surges. Also note the duration of this event is not much more than one power frequency cycle which again is quite common in switching surge events.

Sources of Switching Surges

The reason switching surges exist is because of the inherent inductance and capacitance of power systems. The lines and transformers are major contributors of inductance. The lines are also very capacitive relative to earth and other phases. Cables in underground systems offer significant capacitance to systems. Capacitor banks and reactors also add reactance to the circuits. Whenever these inductive and capacitive components are added or removed, they require the system to find a new steady state voltage level and current flow. In the process of making the transition from one system configuration to the next, voltages rise and fall rapidly seeking a new balance. The currents flow accordingly and often cause current surges simultaneously with the voltage surge.

In the circuit shown in Figure 2 several types of switching surges can be created when S1, S2 or S3 are operated. If S1 is closed to energize the line, a 1pu surge travels down the line toward the transformer and is reflected back toward S1. This reflection can cause a 2pu switching surge that will appear on the system and put all insulation in a higher stress situation.

Another scenario is if upon closing or opening S2 and S3 either pre-strikes or re-strikes of the switch can lead to switching surges 2pu to 3pu as shown in Figure 3.