| 摘要 |
<p>An arrangement for monitoring a current network, to which is connected at least one self-excited or separatelyexcited three-phase synchronous machine which is in operative connection with, for example, an instantaneous stand-by unit with an energy-storage means. A monitoring unit, controlling the mains switch, is connected between the neutral point of the three-phase synchronous machine and the neutral conductor of the network. The monitoring unit comprises an Mp current transformer followed by a load, and a frequency relay. The frequency relay determines the zero passages of the voltage occurring at the load. The falling of the zero-passage frequency, below a predetermined value, serves as a signal of a mains failure, for actuating the mains switch, and/or for other switching procedures. The outputs from the loads are connected in series and the terminal outputs are connected to the frequency relay, for the purpose of monitoring a plurality of three-phase synchronous machines.</p> |
