| 摘要 |
Consists in applying at the point of connection of the network of a telemetry module of subscriber lines for the switched telephony network, which is of passive nature, dedicated to analog lines, whose activation is done remotely from the exchange, performing two resistance measurements with opposite polarities, making use of semiconductor elements with a single direction of conduction and determining whether the presence of a low insulation, as observed from the exchange, occurs before or after the point of installation of said telemetry module, while the user has his private installation connected by means of a pull-off cover, provided with a spring and corresponding protector actuating a switch which acts on the telephone line and at the same time cuts off the service to the private branch network.
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