Overview; Features; Installation; Current Sensor - Cybertronix SENTINEL EFI-MLZ User Manual

Sentinel™ EFI-MLZ User's Manual

2. OVERVIEW

The Sentinel EFI-MLZ is one of a family of Earth Fault Indicator (EFI) products that is designed to
assist in the rapid location and isolation of earth faults on high voltage cable networks. The EFI can
be used in radial networks or in openly operated ringed networks. When an asymmetrical current
greater than the trip level (50A default, factory programmable) in a 3-phase cable system is
detected, an earth fault is indicated by means of a flashing LED (light emitting diode) indicator. The
path of the fault current from the feeding point to the fault location is marked by the triggered EFI's.
The defective conductor segment is located between the last EFI which has been triggered and the
first EFI which is still inactive.

3. FEATURES

• Mains powered
• LED indication
• Auxiliary relay output contact
• Remote indication driver
• Split-core current sensor
• 50A nominal trip (factory programmable)
• 50ms minimum fault duration
• Manual test and reset facility
• IP65 environment protection
• Rugged and reliable electronics
• ISO9001:2000 based quality assurance
• Electromagnetic compatibility

4. INSTALLATION

4.1 CURRENT SENSOR

The Sentinel current sensor consists of a flexible steel core which is wrapped around the three-
phase system to be monitored and fastened tightly in place with adjustable cable-ties. The current
sensor is normally shipped fastened in a closed position. The cable-ties are released by depressing
the small ratchet on the head while bending back the tail. The current sensor and associated leads
must be installed at earth potential on the screened part of the cable and not go anywhere near the
unscreened HV system. Also the current sensor should not encircle the cable earthing. This can
easily be achieved by looping the earthing lead back down through the current sensor so as to
bypass current sensor.
The current sensor is available in three different sizes depending on whether it is to be applied to
an installation consisting of a multi-core cable or a system comprising of three single-core cables.
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