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T e c h n i c a l I n f o r m a t i o n
Battery voltage monitor output
This output allows the System Management Unit to monitor the voltage
level (nominally 48V) of the internal lead-acid batteries.
Circuit breaker sense
When the battery circuit breaker is open this signal is connected to 0V.
When the circuit breaker is closed (i.e. batteries are connected), this signal
is open.
AC Current Monitor
This analogue output indicates the rms value of the current being drawn
by the input AC-DC converter from the AC supply when the PSU is in
Power On or Backup mode.
DC Current Monitor
This analogue output indicates the current being drawn from the internal
batteries when the PSU is in Backup mode.
Thermal alarm
This output is used to indicate PSU cooling failure, for example caused by
fan failure or obstructed vents. The sensor will be thermally coupled to a
component which will overheat quickly in the event of cooling failure, or
will sense the exhaust air temperature. The normal state of the signal will
be high. When cooling failure occurs, the PSU will drive the output low.
15A Latch
This active low output is used to indicate that the PSU has drawn 15A or
more from the AC supply.
The PSU has an input current detect circuit (with a bandwidth of 0.1Hz)
which is used to set the 15A Latch. When the output goes active, the PSU
will enter 15A Latch mode. In this mode, AC Good is driven to False to
indicate that the batteries are providing some of the power. This will
greatly reduce the AC input current as most of the power will be drawn
from the batteries in this mode. When the System Management Unit
pulses Power Up to exit Backup mode with 15A Latch aserted the unit
will revert to AC operation. If AC current is greater than 15A the PSU
will remain the the backup mode with 15A Latch aserted. If the AC
Current is less than 15A , the PSU will de assert 15A Latch and change to
the Power On mode. If the AC Voltage is less than the minimum
operating voltage (85V ac) the PSU will remain in the backup mode and
de asert 15A Latch.
OWNER'S HANDBOOK 5-53
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