Maintenance
HPR800XD Auto Gas  –  806500  5-5
Sequence of operation
  1. Power-up  –  The system verifies that all of these signals are off at power-up
  Coolant flow off
  Chopper current off
  Transfer off
  Phase Loss off
  Chopper 1 over-temp off
  Magnetics over-temp off
  Coolant over-temp off
  Plasma start off
  2. Purge  –  Air or N
2
 gas flows through torch for 20 seconds
  Coolant flow on
  Primary contactor closes and the chopper performs a chopper test and a current sensor test
  Secondary contactor closes and the system tests the secondary choppers and current sensors
  Plasma start off
  Both contactors remain closed in the next state
  3. Idle
  Gas pressure ok
  Coolant flow on 
  Chopper current off
  Line voltage ok
  4. Preflow  –  2 second flow of gas
  Primary and secondary contactors are closed
  5. Pilot Arc  –  Current flow between electrode and nozzle
  Chopper, main contactor and pilot arc relay are on
  High frequency present
  Chopper current sensor = pilot arc current
  6. Transfer  –  Pilot arc current sensed on the worklead
  7. Ramp-up  –  Primary chopper current increases to set point and gas changes to cutflow
  Coolant flow on
  Gas pressure ok
  Phase loss on
  Line voltage ok
   After the primary choppers reach maximum current (400 amps), the secondary choppers increase current 
output (if necessary) to a final setpoint
  8. Steady State  –  normal operating parameters
  Coolant flow on
  Gas pressure ok
  Phase loss on
  Chopper 1 over-temp off
  Magnetics over-temp off
  Coolant over-temp off
  9. Ramp-down  –  Current and gas flow decreases after plasma start has been removed
  Cutflow gas off
10. Auto Off  –  10 second postflow
  Main contactors off
  Choppers off