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Heavy Duty Edge Switches Installation and User Guide(07/05)
60
4.4 Hardware operated Alarm Contact
for monitoring internal power supply
The two screws Alarm Contacts feature, standard on Black Box LBHXXXA(E)-H
and P, provides Normally Closed (NC) contacts to which the user can attach one sets of
status monitoring wires at the green terminal block. When this option is present, the
terminal block for Alarm Contacts is part of the Power Input panel in the Black Box
LBHXXXs case. The DC power input connection is in the same panel.
The NC Alarm Contact is held close when there is power on the
main board inside of the LBHXXX. This provides a
“Hardware operated Alarm” because the NC
contacts will open when internal power is lost,
either from an external power down condition
or by the failure of the power supply inside of
the Black Box LBHXXX Switch.