Specifications

Revision: 2010-01-20
4-1
4 Powering
4.1 Plug-in
Each plug-in is fed via the subrack backplane with dual -48VDC (referenced to
0VDC of the exchange battery). The plug-in generates the used voltages on-
board.
Additionally, the plug-in is fed over the backplane with an auxiliary +5VDC supply
(referenced to ground) generated on the ACU. The only purpose of this voltage
is to drive the alarm circuitry on each plug-in, even in the case of a failure of the
plug-in onboard powering circuitry
4.2 Tabletop
The tabletop modem is normally powered locally from an AC/DC adapter with
48VDC output. Power adapter SZ.410.080.V1E is available from Schmid Tele-
com to power the tabletop modem.
Caution:
Only power sources below maximum hazardous energy levels according IEC
60950-1 chapter 1.2.8.10 may be used as local power source. The insulation
voltage of the power source must support elevated insulation voltage according
to EN 60950-1 (at least 4 KV insulation). The power adapters available from
Schmid Telecom fulfill these requirements.
Caution:
Do not connect a 48VDC supply directly to the “AC/DC adapter” connector. High
voltage transients from the DSL line may damage the modem or other equipment
connected to the battery. A DC/DC converter with 4kV transient isolation voltage
must be used in this case.
Caution:
The local supply voltage input is protected against reversal of polarity but not
fused. Appropriate fusing has to be done externally.
The tabletop modem can also be powered through the DSL span from to a Wat-
son TDM plug-in modem with remote powering functions. Switching between lo-
cal and remote powering is done automatically with local power taking prece-
dence over remote power feeding.
Note:
The Watson Ethernet plug-in does not support remote powering of a tabletop.
The ground of the tabletop modem is normally floating when referenced to earth.
A ground connector (Faston type) is available on the rear panel of the modem.