ADC and 3 Doubler - Manual (Page 35)

LTPH-UM-1234-01 Appendix C - Ground Faults
HDU-409 Lists 1, 2, and 3 April 30, 2003 29
A
PPENDIX
C - G
ROUND
F
AULTS
G ROUND F AULT D ETECTION
The HDU-409 has Ground Fault Detection (GFD) circuits as described in
R7-1, Section 7.2.1 of GR-1089 CORE, Issue 1, Revision 1, December, 1996.
When used with HiGain line units, ground faults occurring at any point along
any span are immediately detected. Ground fault conditions shut the HiGain
circuit down. The line unit periodically tries to apply power to the first span
to determine whether the fault condition is still present. As long as the
condition exists, the power cycling and ground fault protection continues. To
discontinue the ground fault protection, locate and repair the fault in the
cable.
Circuits containing both the HDU-409 and older doublers without a GFD
circuit also support this new ground fault detecting feature, provided the
doubler nearest the HLU is an HDU-409.
To operate properly, the ground fault circuit requires that the
doubler enclosure ground plane be securely connected to
earth ground. Failure to do so can cause false triggering of the
GFD circuit.