| 摘要 |
<p>Apparatus for detecting and locating a fault in an electric cable using a pulse-echo technique comprises means for injecting step function or single pulses into a cable, under two different conditions of the cable. and means for retrieving the signals obtained under the two said conditions. comparing them and thus locating the position of the fault. Preferably, the apparatus also includes means for detecting whether the cable is "live and healthy" or "live and faulty" by obtaining a digital pulse signal indicating that a voltage is present on the cable, obtaining a second digital pulse signal indicating by a series of pulses when the current in the cable is above the normal load current and gating these two signals in a NAND gate to obtain a signal representing the state of the cable.</p> |
