Hypertherm HPR260 Manual Gas Preventive Maintenance Program Rev.5 - Manual (Page 149)

MAINTENANCE
HPR260 Auto Gas Instruction Manual 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 opens 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