Fault circuit indicators are used to detect
phase to phase or earth faults or short circuits in medium voltage net:
a change-over contact is used to remote the over-current tripping while
a local LCD display indication is used to select the faulted area of
FI/X/X is able to detect both phase to phase of phase to earth faults
according to current sensors used for detection: to detect earth fault
situations a three phase current sensor must be used.
The high sensitivity of earth fault indicators allow to use them in the
most typical application.
Connection between tripping device and current sensor is made by
The energy to trip the remote indication relay is derived by fault
itself, while test and manual reset are energized by internal li-ion
battery (20 years is the estimated life time).
A diagnostic test can be performed locally by pressing a push-button.
Reset con be performed locally by a second push button or by a remote
The device with stable relay maintain the changeover fault indication
during the whole timing before reset, the latched one lasts only for
The local LCD indication always lasts the whole timing before reset.
The sensors detect earth faults and short circuits inductively. The
operating points for earth fault and short circuit are adjusted with a
threshold level electronic. When the current exceeds the pre-adjusted
threshold level, a signal is sent to the reading instrument for
evaluation. The respective LCD indication is activated and starts to