Application Note www.megger.com Figure 2: Current vs voltage curve of a maximum continuous operating voltage arrester Image from Arrester Work “Arrester Reference Voltage” link As can be seen in the graph of Figure 2, an arrester has a high and constant (straight line) resistance in the operating range. Above that, the resistance drops dramatically allowing a lot of current to pass through it. So, an arrester’s main task is to maintain the optimal voltage condition of the other parts of the system by diverting or drawing excess electric power away. They are installed by connecting one side to earth/ground and the other to the system but in parallel with the asset they are protecting. Usually, the arrester is protecting a transformer (see Figure 3). Figure 3: Arrester connected to earth/ground and in parallel to a transformer
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