| 摘要 |
A portable device for fault detection in the electrical insulation of an electrical or electronic installation powered by a distribution network in which the neutral is connected directly to earth (known as the TT mode) equipped with a quick-trip protective circuit breaker (4). The device (1) connected to the network comprises an isolation transformer (5) coupled to a leakage current detector circuit (6). The installation to be monitored (2), connected to the device (1), is equipped with an insulated conductor (7) which is connected to an electrical earth (8) of the device (1) through a resistor (9). When an insulation fault occurs, a leakage current flows in the conductor (7) and then in the resistor (9); the voltage across the terminals of this resistor is filtered and compared with a threshold value in a comparator (11) and then triggers a luminous alarm (13) via a relay (14) if this voltage is greater than the threshold value. Application to the detection and location of faults in the insulation of an installation, of apparatus or of a component in apparatus (e.g. an electronic card) connected to a distribution network in TT mode. <IMAGE>
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