150-412-107-03, Revision 03
Appendix B - Functional Description
HRU-412 List 7
November 19, 1999
23
shows a block diagram of the HRU-412 List 7.
Figure 7.
HRU-412 List 7 Block Diagram
L
OCAL
AND
L
INE
P
OWERING
The HRU-412 List 7 unit can be line powered or locally powered. It always
chooses the local -48 Vdc power source, if present. It defaults to line power
only in the absence of local power. Some older HLUs automatically turn off
their line powering when connected to the HRU-412 List 7. The older
versions of the HLU-231 (Lists 1, 2, 3, 3A, and 4) must have their PWRF user
option disabled for them to work properly with a locally powered
HRU-412 List 7. Refer to the appropriate HLU technical practice if you need
more information about its local and line powering capabilities.