The Earth Fault Indicator (EFI) is a equipment that measures the Earth Fault Current in a 11kV transmission system by using a Split-Core Current Transformer and raises an alarm when the current is over a preset limit. The EFI has Isolated I/O contacts suitable for connection to the SCADA system via Field/Remote Terminal Units. The EFI is powered by a single Lithium Battery and is of Ultra Low Power Design to ensure a battery life of 10+years.
The EFI has two components; the Detection and Signalling unit and the Current Transformer:
The Detection and Signalling unit is a stand-alone battery powered system which monitors the signals from the current transformer and triggers an alarm if the value exceeds a set limit. The unit gives visual indication with a high powered LED which is visible for long distances even in daylight. The triggered alarm can be reset manually using a push-button, through signals from a SCADA connected terminal unit or automatically after the elapse of a set timing. The EFI has user configurable settings for Trip Current Value, Trip Current Duration, Alarm Auto-reset time and 230V AC sensing.
The Current Transformer (CT) is a Core-Balance type Split-core current transformer with suitable insulation that can be easily mounted over 11kV cables without need for breaking the line. The CT is suitable for outdoor operation and can withstand being submerged in water for prolonged periods of time. The CT is designed to saturate during heavy earth faults to protect the EFI from damage. The Current rating and diameter of the CT can be modified as per customer requirements.