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Sentinel™ EFI-BFZ
User's Manual
The indicating unit continuously monitors the output signal from the current sensor. The current
sensor transmits a voltage which is proportional to the measured current. For primary currents in
excess of 50A the current sensor saturates and a limiting circuit inside the indicating unit clamps
the output voltage to below 10V even for high fault currents.
When an imbalance is detected, onboard circuitry analyses the fault current. The magnitude and
duration of the half cycles of fault current are measured. Current spikes and glitches are ignored. As
soon as valid fault current has been detected, the Sentinel™ triggers and enters a tripped state.
The indicating unit is powered from a long-life lithium battery. The unit will reset from an on-board
timer after 4 hours or 8 hours (selectable via jumper) of LED flashing.
5.2.1 AUXILIARY RELAY (OPTIONAL)
An on-board auxiliary relay provides a potential-free, normally-open contact for additional signaling.
A 2-way screw terminal is provided on-board to which the user can connect a signaling cable. A reset
will latch the relay into the reset position (open). A tripped state will latch the relay into a tripped
position (closed).
5.2.2 REMOTE INDICATOR (OPTIONAL)
An optional remote indicator can be ordered pre-installed or ordered separately. A 2-way screw
terminal is provided on-board for connection of the remote indicator. It provides flashing LED
indication at some distance from the main indicating unit. During a tripped state the unit will flash
at a rate of about 1Hz. The remote indicator is weather-proof and is housed inside a stainless steel
bolt which also makes it vandal-proof.
5.2.3 MANUAL TEST AND RESET
A magnetic reed switch on-board allows the unit to be manually tested. The switch can be activated
externally with a small, strong magnet, without opening the enclosure. The reed switch is located
on the right-hand side of the unit. The test feature can also be activated manually via a push-button
located on the printed circuit board inside the enclosure. The manual test feature can both trip and
reset the EFI, as well as test the battery. After being manually tripped the unit will automatically
reset after 60 seconds to prevent inadvertant wastage of the battery.
5.2.4 BATTERY SUPPLY
The Sentinel™ EFI-BFZ-50 is powered by a replaceable, long-life, ½AA, 3.6V lithium battery. The
battery has a shelf-life which easily exceeds 10 years. During normal operation the quiescent current
if the device is so low that it approaches the self-discharge rate of the battery. Significant current is
only consumed when the device trips for an earth fault. Even then the power consumption is very
economical and the device yields more than 1000 flashing hours. The state of the battery can easily
be checked by manually testing the unit. If the battery is still healthy then the device will initially
flash rapidly (10 Hz) for a couple of seconds and then commence to flash at its normal rate (1 Hz). If
the battery requires replacement then on activation of the test facility, the indicating unit will only
flash at its normal indication rate (1 Hz) or not at all. The device is protected against battery reverse
polarity.
Version 3.2
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