LEM's Sentinel 3+ is a battery-monitoring transducer that measures
the voltage, temperature and impedance of cells and complete batteries in
uninterruptible power supply (UPS) installations of all sizes up to mega-watt
back-up power supplies for data centers and hospitals. Sentinel 3+ reports its
measurements - on valve-regulated lead-acid (VRLA), gel or flooded stationary
batteries - to supervisory systems over a dedicated communications bus, and
offers a unique capability to assess the true state-of-health of UPS batteries
while they are in service. Sentinel 3+ gives complete confidence that battery
arrays will deliver their rated power when called on to do so, and identifies
weak and failing cells without the need to remove them from service for cycling
Technology developments such
as the availability of fast insulated-gate bipolar transistors (IGBTs) reduce
costs by eliminating transformers from their circuit configurations. The
battery packs that the Sentinel product monitors are operated in a floating
voltage mode: the battery is subjected to higher ripple currents, and the
monitoring circuitry must handle high common-mode voltages, with superimposed
high-amplitude, fast transients.
LEM's Sentinel 3+ has upgraded
algorithms to address more challenging measurement environments and improved EMC
immunity and enhanced robustness. Sentinel 3+ delivers voltage measurements
over a range of 0.9 to 16 V with an accuracy of +/-0.5 percent; impedance
measurement from 0.05 to 250 mO with repeatability of +/-2 percent.
Sentinel 3+ features Common Mode Transient Immunity up to 20 kV/µsec with a
common-mode voltage level of +/-600 V, and a transient repetition rate of 20
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