MONITORING OF INSULATION AND HELP WITH FIRST FAULT LOCATION

Systems for insulation monitoring and help with first fault location have been developed and provide a significant reduction in the number of maintenance and repairs operations.

The principle implemented consists in applying a low frequency or d.c. low voltage between the network to be monitored and earth using a suitable generator. When the insulation decreases a leakage current is established. The measurement of this current helps to evaluate the level of network insulation and locate the position of an eventual fault.

Only systems injecting a low frequency signal allow faults to be located. These may be used both on direct current and alternating current installations and some are able to distinguish between the resistive part and the capacitive part of the earth current and thus carry out a true measurement of the network insulation resistance.

Modern systems allow the insulation resistance of each circuit to be continuously measured; prevention of the first fault thus becomes possible. The measurements carried out in an installation are transmitted by digital link to a central processing unit which supplies all the information necessary to the users.

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