Maintenance
HPR400XD Auto Gas  –  806160  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 overtemp off
  Magnetics overtemp off
  Coolant overtemp off
  Plasma start off
  2. Purge  –  Air or N
2
 gas flows through torch for 20 seconds
  Contactor closes and the chopper performs a chopper test and a current sensor test
  Plasma start off
  Contactor remains closed when the purge cycle ends
  3. Idle
  Gas pressure ok
  Coolant flow on 
  Chopper current off
  Line voltage ok
  4. Preflow  –  2-second flow of gas
  5. Pilot arc  –  Current flows 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  –  Chopper current increases to its setpoint and gas changes to cutflow
  Coolant flow on
  Gas pressure ok
  Phase-loss on
  Line voltage ok
  8. Steady state  –  normal operating parameters
  Coolant flow on
  Gas pressure ok
  Phase loss on
  Chopper 1 overtemp off
  Magnetics overtemp off
  Coolant overtemp off
  9. Ramp-down  –  Current and gas flow decrease after plasma start has been removed
  Cutflow gas off
10. Auto Off  –  10-second postflow
  Main contactors off
  Choppers off