Emerson 2468CD Weather Radio User Manual


 
Hydrastep 2468CB & 2468CD Manual Remote Display Options 24683B, C & D
24685034 4-7
4.4 ELECTRICAL INSTALLATION
Up to six remote displays may be driven by the Hydrastep 2468 unit. One remote display can
be powered from the main unit, but all the others must have a local supply. A remote display
has a dual serial data input and a dual power input. When the remote display is powered from
the main unit an eight-core cable is required to connect the two units. When a remote display
is locally powered, however, a six-core cable will suffice. See the example in Figure 4.4:
remote display unit 1 is powered from the main unit and uses an eight-core cable; remote
display unit 2 is locally powered and uses a six-core cable. All cables must be screened to
comply with the EMC directive.
For remote displays powered from the main unit the loop resistance of the power conductors
must be less than 27 ohms for an a.c. powered unit or 7 ohms for a d.c. unit. To provide for
cable runs of up to 1000 metres, without the use of heavy cables, the main unit and the remote
display unit each have internally linked multiple terminals for the power and ground connections.
This allows the power and ground lines to be doubled to reduce the loop resistance.
Figure 4.2 - Interconnection cable for a single remote display