Appendix B
724-746-5500 | blackbox.com
Page 28
APPENDIX B: DC Power Input
B1.0
Specifications for LBH08x/LBH18x Switches, DC Power at 12, 24 and
–48VDC Power input
Each Black Box LBH08x/LBH18x Switch requires DC power input, at 12, 24
and 48VDC. The wide range of DC power input types qualifies this product for use in
12, 24 and 48 applications in different industries.
DC Power Terminals
: “+”, “
-
”
are
internally floating so that user may ground either
GND
: ground wire connection to the chassis (#6-32 thread)
Power Consumption:
8 watts typical, 9 watts Max.
12VDC Power Input nominal (range 9 to 15VDC)
24VDC Power Input nominal (range 18 to 36VDC)
-48VDC Power Input nominal (range 36 to 60VDC)
B2.0
12, 24 and –48VDC
POWER, THEORY OF
OPERATION
The 12, 24 and -
48VDC power options are
designed using diodes inside
on each DC power input line
behind the two external power
connection terminals, so that the power from an external source can only flow into the
hub. This allows the Switch to operate only whenever DC power is correctly applied
to the two inputs. It protects the Switch from incorrect DC input connections. An
incorrect polarity connection, for example, will neither affect the Switch, its internal
power supply, nor will it blow the fuse in the internal power supply.
B3.0
APPLICATIONS FOR DC POWERED ETHERNET SWITCHES
Black Box LBH08x/LBH18x Switches are easily installed in a variety of
applications where 12, 24 and -48VDC power is used as the primary power source.
The DC power configuration capability provides an Ethernet networking solution
utilizing a special power supply in switches with a proven track record.
The –48VDC solution is particularly useful in the telecommunication
industry, where it is common for facilities to operate on -48VDC power. Such
companies include regular and wireless telephone service providers, Internet Service
Providers (ISPs) and other communication companies. In addition, many high
availability equipment services, such as broadcasters, publishers, newspaper
operations, brokerage firms and other facilities often use a battery backup system to
maintain operations in the event of a power failure. It is also frequently used for
computer system backup, management and operations monitoring equipment.
