| 摘要 |
PURPOSE:To enable to apply the power supply of each communication unit automatically, by detecting the leading of the power feeding voltage when the voltage is first fed to the feeding line. CONSTITUTION:When the power supply switch of the communication unit N1 is twined on, the power feeding voltage at the power feeding line 2 is increased and the power supply feeding voltage detection relay of other communication units is operated. Since the charging current flows to the capacitor C with the closing of the contact rl1, the power supply relay RL3 is energized to close the power supply contact S. Thus, AC voltage is fed to the power supply 5. Accordingly, DC voltage is fed to the relay unit 3 from the power supply 5. In this case, the output voltage detection relay RL4 is operated, allowing to feed power to the relay unit 3 from the power feeding line 2. |
