Abstract: An apparatus for monitoring telecommunication transmission is disclosed that a resistance detection unit having a plurality of resistors connected in series is connected between an input terminal of a transformer in a power supply at an absolute ground potential and a high voltage output terminal of the transformer at a relative ground potential. A photo-coupler transistor is connected in parallel with one of the resistors such that the photo-coupler transistor is conductive when a leakage current flows through the resistor, thereby generating a low potential signal. The low potential signal is transmitted to a central processing unit through a logic gate. Upon reception of the signal, the central processing unit will shut down the power supply for security.

Abstract: A method and apparatus is described for providing uninterrupted DC and selectable AC power depending on the value of utility-supplied AC voltage range. In the AC 115 V output case, by means of setting a selecting switch and switching a relay port, the DC/AC inverter will function as a half bridge switching circuit upon power failure and use the mid-point of series connected filtering capacitors as a relative ground reference point, to provide an AC 115 V output; in the AC 230 V output case, by means of different setting of the selecting switch and switching a relay port, a DC/AC inverter will function in a full bridge circuit upon power failure and use the full voltage of the series connected filtering capacitors, to provide an AC 230 V output. The power source of the control circuit in the backup portion is interlocked and sequentially controlled for the purpose of power saving.