ST950S Plus+ Installation and Commissioning Manual
10. Fault Finding
This section contains information to assist in location and diagnosis of faults.
Important:
When replacing any components (including cards) only approved spares may be used. Use of
any other components may invalidate the Type Approval of the equipment.
10.1. Site Visits
This section provides a reminder of considerations to be made before visiting a site, and actions to be
taken on site and before leaving.
For the tools and essential spares required when making a site visit, see section
10.1.1. On Receipt of a Fault Report
When a fault report is received it is recommended that the following are checked:
a) Is the fault a repeat one; i.e. is the fault and its cause known from previous visit. Why was the
controller left faulty? Can it now be cleared? I.e. are the resources now available to clear it; if so go to
site. If not, make an appropriate note in the fault recording system, or on your fault report.
b) If the report is DFM, i.e. detector fault, check to see if a fault is known to exist on the site, especially
if the fault is reported by an OMU as it may be a repeat alarm for a reported fault. Because, unlike the
controller, most OMUs cannot be made to ignore faulty loops which have already been reported and,
therefore, continue to raise the alarm.
c) If the controller is under UTC control, check with UTC centre to ensure that the fault report is not a
result of any problem with the UTC, e.g. OTU may be out of action or faulty.
d) If the Signal State is reported as being All Out, All Red or not giving right-of-way to one approach try
and check with the local authority/police as to whether they know of a requirement for the signals to be
in this state.
e) Check that after clearance of the fault the controller may be re-commissioned and switched on
again; in some cases the local authority may require the signals left off.
10.1.2. Before Going to a Site
Before leaving for a site visit, it is recommended that the following be checked:
a) Check that you have the correct equipment and sufficient spares to do the job you are going out to
do. See the spares list
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