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Sentinel™ EFI-BLZ
User's Manual
1. OVERVIEW
The Sentinel™ earth fault indicator (EFI) is an electronic relay used for the rapid location and
isolation of earth faults on HV cable networks. The EFI can be used in radial networks or in openly
operated ringed networks. 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.
2. FEATURES
• Battery powered
• LED indication
• SCADA relay output contact
• Remote indication driver
• Split-core current sensor
• Three selectable trip levels or factory preset trip level
• 50ms minimum fault duration
• Manual test/reset facility
• IP65 environment protection
• Rugged and reliable electronics
• ISO9001 based quality assurance
• CE approved
3. INSTALLATION
3.1 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 should not encircle
the cable earthing as well. Instead, the cable earthing should bypass the current sensor.
The current sensor is available in two 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.
3.1.1 MULTI-CORE CABLE SYSTEM
Unless ordered otherwise, the unit ships with a standard current sensor sized for application on a
multi-core cable. The flexible sensor core is mounted on the screened part of the cable, below the
stripback point. The core is wrapped around the cable and the cable-tie is pulled tight as far as it will
go. A second cable-tie is used to hold the core firmly onto the cable. The cable screen is turned back
underneath the core and then terminated to earth as shown in the Figure 1.
Version 4.1
Page 4 of 11
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