Page
34 of 40
Issue 2
13/12/99
PETS-2 Crossing Telephone System
QUICKFIX INSTALLATION HANDBOOK
34
The simple arrangement above is the most common form of installation. A more complex
arrangement would be detailed by the System design Authority if ‘Block Switching’ is
required.
5.8.4 Miscellaneous Wiring
The functions of each circuit are detailed in the table of section 5.6 The hardware of
Signalbox and level crossing Units is identical and some circuits are redundant, particularly
at the Level crossing end. This section will briefly summarise some of the possible
alternative functions, but will not detail the installation method since this will be provided by
the System Design Authority if required:
•
2 wire operation - a dedicated transmission circuit pair (T2) is allocated to operation over
a since pair. PETS incorporates an electronic hybrid based upon 600R operation.
•
Block switching - a Level Crossing unit may be controlled by different Signalboxes (at
different times). Circuit T2 is used for switching the transmission circuit under control of
the Block Switch of an Intermediate Signalbox. A dc control circuit is provided to allow for
an input signal from a common ‘Block Switch’ in the Signalbox.
•
Alarm Outputs - Major and minor alarm outputs are available on volt free contacts for
connection to automatic fault reporting systems (SCADA).
•
External Call Sounder - In some instances the Signalbox equipment may be remote from
the Signaller and require a separate call sounder. volt free relay contacts are provided for
this purpose.
•
Command, control and monitoring - sometimes it is necessary to transmit low priority
alarms between Signalbox and crossing. PETS2 allocates Line 1 at each end for bi-
directional signalling power supply and charger failure alarms. Three additional signalling
circuits are available if a full compliment of Line cards are equipped at each end. These
I/O circuits are pre-wired to the QDF blocks in each Junction Box.
•
Remote Alarm Display - this new product for use with the Signalbox Unit may be wired
into the QDF connections of Block 1, allowing alarms to be remotely viewed and
acknowledged.
