FI-3P3O indicator is installed in the RMU and pad-mounted switchgear, it used for the remote indication of underground fault. The FI-3P3O fault indicator can remotely indicate the fault by connecting the detectors with optical fiber as well as transferring the data by electric signal via dry contacts.

The potential-free connection between short circuit detectors and earth detector to the FI-3P3O indicator is done by optical fibers. A manual reset button is set at the front of panel, by long press; the battery status of indicator can be checked. One 3.6V battery is assembled in the fault indicator for power supply, ensuring that the panel indicator can work 1000 hours without maintenance.

Local LED indication, battery cannot be replaced, external source is not available.

When short circuit fault or earth fault occurs, fault indicators in front of the fault point will flash or turn flag to indicate the fault, the indicators behind the fault point will not indicate the fault. The operator can identify the fault area (between the last flashed indicator and the first non-flashed indicator) by following the flashed indicators. It can help operator to find out the fault point quickly.

The Di/Dt principle is used for fault determination and indication. When fault occurs, the current flow in the line will increase suddenly, the internal magnetic field will change, and the fault indicator will determine the fault based on surge value and duration of the short circuit current.

CREAT is the first company to detect the earth fault with signal injection method by assistance of a device called signal source, and the earth fault accuracy is improved greatly after using the signal source.

The fault indicator is designed and tested as per IEEE 495-2007 international standard.