Electrical installations must meet continuity of supply requirements, together with protection of life and property.
The IT system provides perfect guarantee in terms of continuity of supply. Even when a first insulation fault is present, the installation can continue to supply power without endangering human life.
Before a second fault occurs, however, the first fault must be detected and repaired. The job is done by insulation meters.
Vigilohm insulation monitoring meters available from Schneider Electric are designed to:
- Measure the insulation level of the installation
- Indicate drops in the insulation level below a user-defined threshold
- Automatically locate the faulty circuit
Insulation meters inject a DC or low-frequency AC voltage between the installation and earth.
Insulation resistance is determined by measuring the resulting leakage current.
Insulation meters use an indicator light to signal the presence of an insulation fault within the installation. They are meters (multi 9 format) designed for small installations or sub-systems isolated from earth.
TR22A and TR22AH (for hospitals) meters detect insulation faults and, in addition, continuously indicate the value of the insulation resistance on a digital display.
XM200 (part of the Vigilohm system range) can be associated with automatic fault locating devices.