Fault indicator

For example, the purpose of the engine-check light commonly found on the dashboard of motor vehicles is to indicate whether or not there is a fault with the engine.

Typically fault indicators sense magnetic field caused by current flows through a conductor or cable.

Upon energization of the lines there could be high inrush current which may lead the fault indicators to false operation.

To monitor the live line, some fault indicators look only at the magnetic field caused by the load current.

to be independent from the load current, some FI’s look at the E field[clarification needed] to check the voltage directly.

In such cases the user should consider the downstream capacitive discharge current to avoid false operation of the non-directional indicators.

More recent fault indicators communicate their status (tripped or reset) via cell signal or radio to a central station, handheld device, or pole-mounted receiver.