Meridian America 51 User Manual

The SL-1 system is an advanced telecommunications system providing state
of the art functionality to the customer. The associated power system provides
the necessary power for system operation.

The power system required by the SL- 1 system can be divided into two main
categories: external and internal.

The external system consists of the power source and power plant which is
located outside of the SL-1 system. This includes the power plant and the
reserve power plant, if required, as well as the distribution and grounding
components.

The internal system consists of the hardware within the SL-1 system which
distributes and converts power. This is made up of a specific power
distribution unit 

 shelf power converters or power supplies as well as

distribution cables and grounding hardware. The internal system is chosen to
suit the existing or specified external power system and cannot be changed in
the field.

There are two basic powering schemes which cause both the internal and the
external hardware to change 

AC powering and DC powering. The choice

of which powering scheme to use is up to the customer and is determined by

system cost, reserve power requirements and the type of existing equipment at

the  site. See Installation  planning  (553-3001-120). Figures 1 and 2 show the
two basic schemes. Note that both require a source of commercial AC power.
In Figure 2, because of the required rectifier, it is referred to as the DC system,
which means that the PBX will require a nominal 48 V dc at its input
terminals located in the pedestal.

The PBX in Figure 1 requires a nominal

208 or 240 V ac at its input terminals located in the pedestal.

Power engineering 553-3001-l 52