Users Manual

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EFFECTIVITY
© Honeywell International Inc. Do not copy without express permission of Honeywell.
Page 4-45
22 Apr 2019
23-15-49
SYSTEM DESCRIPTION, INSTALLATION, AND MAINTENANCE MANUAL
ASPIRE-400
7. Power Conditioning Characteristics
A. Secondary Power Monitoring and Control
(1) All secondary power rails are monitored for in-tolerance/in-alarm assessment.
(2) The power supply design implements overload protection measures to mitigate harm to
primary supply or internal failure. Overload protection schemes such as clamping, current
limiting, current foldback or other methods are deployed as deemed necessary. The
power supply design should consider evaluation assessment of protection measures for
determination of in- tolerance/in-alarm status.
(3) On detection of the occurrence of a monitored condition exceeding its alarm threshold
the HPA identifies the offending sensor as "in alarm" and record that event to the fault log
(L2=04) with status as Active.
(4) A monitored power supply metric established as "in alarm" relinquishes that status on the
occurrence of transition to in-tolerance condition and record that event by setting the
corresponding event in the fault log status as Inactive.
(5) For the current ARINC-429 label 350 HPA Maintenance word reporting interval the
following applies:
(a) When the voltage/current sensors persist in an alarm state greater than 500ms
then the "Internal Power Supply" status is reported as "Power Fail" and the SSM
is set as FW in the ARINC-429 label 350 HPA Maintenance word.
(b) When the voltage/current sensors persist in an alarm free state greater than
500ms then the "Internal Power Supply" status is reported as "Power OK" in the
ARINC-429 label 350 HPA Maintenance word.
(c) When the voltage/current sensors persist in an alarm state less than 500ms then
the "Internal Power Supply" status remains the same as the status reported in
the previous ARINC-429 label 350 HPA Maintenance word.
(6) The PSU provides a hardware derived "Power Good" status indicator when the
secondary power rails of the power supply is operating within specification.
(7) The power supply design implements current limiting on secondary rails with the
capability of over-current sense and restart hysteresis reaction.
(8) The HPA provides overcurrent limiting protection to no more than 1.5 times the full load
capability. The design considers timed electronic circuit breaker features and active
current limiting with foldback features.
(9) Hardware implemented thermal failsafe switches is used for survival purposes.
(10) The design integrates software initiated survival features to protect from over-
temperature conditions by mitigating power consumption when the temperature exceeds
severe limits.
(11) The design initiates survival features to protect from over-temperature conditions by
disabling primary power when the temperature exceeds critical limits.
(12) Secondary power utilization is designed to be robust against latch-up or other
unexpected behaviors.
(13) Considerations to holding processors in reset during power-On or last gasp is given to
assure controlled restart.
DRAFT
3rd rvw Draft as of:
29 January, 2020