Once  a minute,  the  4020  software  performs  a self-alarm  test  of  each  TrueAlarm’”  sensor.  The  self-alarm  test  raises 
the  value  of  each  sensor  to  a value  that  simulates  an  alarm  condition.  If the  sensor  reports  back  a value  that  is  not 
within  the  alarm  range,  a “self-test  abnormal”  trouble  will  be  displayed  for  that  specific  sensor. 
The  following  paragraphs  discuss  the  responsibilities  of  4020  system  operators  when  these  trouble  indications 
occur. 
ALMOST  DlRTY  INDICATION 
Using  the  front  panel  keypads,  it  is possible  for  a SIMPLEX  Field  Service  representative  to  turn  on  a system  point 
that  allows  an  “almost  dirty”  sensor  to  report  a  trouble.  Although  the  “almost  dirty”  sensor  is  holding  its  sensitivity 
level,  the  4020  operator  can  schedule  maintenance  for  the  sensor  before  the  dirty  sensor  trouble  occurs. 
DIRTY  INDICATION 
A “Dirty”  indication  means  that  the  sensor  is holding  its sensitivity  level,  but  that  the  4020  operator  should  schedule 
maintenance  for  the  sensor.  Clean  the  sensor  as  required  and,  if necessary,  call  Simplex  for  service. 
EXCESSWEL  Y DIRTY  INDICATION 
The  “Excessively  Dirty”  indication  means  that  the  sensor  is no  longer  compensating  for  dirt  and  dust.  Because  false 
alarms  are  possible  with  this  condition,  sensors  must  be cleaned  as  soon  as  possible.  If necessary,  call  Simplex  for 
service. 
SELF-TEST ABNORMAL  INDICATION 
All  4020  system  sensors  are  automatically  tested  once  every  minute.  If a sensor  fails  to  report  properly  to  the  4020 
master  controller,  a  “self-test  abnormal”  condition  occurs.  Since  the  sensor  is  not  working  properly,  it  must  be 
replaced.  Replace  it, or  call  Simplex  for  service. 
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