| 摘要 |
<p>The circuit arrangement has a phase line (L), a neutral line (N) and a fuse line (PE). A voltage dependent resistor and spark path (F) are connected as an overvoltage protection device. The phase line and the neutral line are applied to the fuse line each via a voltage dependent resistor and a spark path. The overvoltage protection device is also connected to the end or near the end of a power lead made up of the phase line, neutral line and fuse line. A load can be connected to the power lead. To measure an insulation resistance of the power lead, the lead is separated from the alternating voltage source and is connected to a measuring constant voltage source. A switch is connected in the phase line or in the neutral line near the connection point of the resistor, or in the lead terminal coming from the resistor. The switch breaks the connection between the phase line or the neutral line and the resistor, or between the neutral line and the phase line. The switch is coupled to an electric or electronic arrangement. This closes the switch when the power lead is connected to the alternating voltage source. It opens the switch when the lead is connected to the measuring constant voltage source.</p> |
