1.3 Distribution Board
The Distribution Board is the distribution point for power around the system. It allows the
connection of external power supplies into the system and the use of external batteries for
backup purposes. It is located at the left-hand side of the main chassis within the MCU Control
Units beneath the Common Relay Module.
There are two main versions of the distribution board – see sections 1.3.2 & 1.3.3
Note that Issue 3 is fitted into all new equipment.
1.3.1 Field Connections
Located on the top edge of the distribution board is a 12 way connector. This is used to provide
connections for inputs, outputs and external buttons:-
Pins 7 & 8
These pins allow the connection of an external normally open switch. This switch will
allow the muting of alarms from a remote location (the control unit is the only location
from which alarm conditions can be accepted or cleared). This button can be configured
to perform other functions if required. Contact Status Scientific Control for further details.
Pins 9 & 10
External 24V batteries may be connected to the system via these pins. This is only
required if it is anticipated that the main power source will be disconnected from the
system for long periods of time, in excess of the internal battery capabilities. Note that
any external batteries must be independently charged.
Pins 11 & 12
An external 24V DC supply may be used instead of having a mains input. Refer to section
2.4.2 for further details regarding connection of an external DC supply. The internal
batteries will still maintain power in the event of the external 24V power supply failing. In
order to meet all the power supply requirements of the system, the external supply must
be rated at 24V DC @ 2A minimum.
Pins 1 to 6
The function of the remaining pins on the 12-way connector depends upon the issue of
the distribution board fitted.
Note:
The issue of the distribution board may be determined by noting the position of jumper
J1. If this not located adjacent to the 4-way connector refer to section 1.3.2. However, if
the jumper is located adjacent to the 4-way connector refer to section 1.3.3.
The jumper position on the distribution board (labelled J1) allows connection of chassis earth to
the system 0V. The fitting of J1 is not always required; section 3.2 discusses this link and
determines whether it should be fitted in a given situation.
An I.S. Earth point is also provided on the distribution board. This is discussed in section 3.3
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