| 摘要 |
PROBLEM TO BE SOLVED: To provide a private branch exchange which has a simple circuit constitution generating no extra heat and having superior productivity. SOLUTION: The exchange has a base unit 35 fed with power from a first power supply 2 for feeding a DC voltage and extension units 36a, 36b fed with power from a second power supply 3 for feeding a DC voltage. All the units 35, 36a and 36b are capable of accommodating terminals. The base unit 35 has a connection detector 4 for detecting whether or not the second power supply 3 is mounted, and a controller 6. When the controller 6 decides that the second power supply 3 changes from a non-mounted state to a mounted state based on the detection result by the connection detector 4, it stops the first power supply 2 from feeding power to the extension units and starts the second power supply 3 to feed power to those terminals in a feed stop state among the terminals accommodated in the extension units. COPYRIGHT: (C)2005,JPO&NCIPI
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