MAINTENANCE
5-6 HT4400 Instruction Manual
HT4400 Plasma START Sequence
The following flowchart shows the sequence from when the plasma START signal is given up to the RUN state.
Shaded boxes indicate action taken by the operator
Plasma START Signal Given
• Pre-flow gases ON
• Main contactor CON1 ON
• DC ON lamp ON
• Pilot arc relay closes after 1 s
• Hold signal released by control board
after 2 s
• Phase loss monitored
• Interlocks monitored
Control board monitors
Hold signal for 30 s
• Gas console displays Hd
• All functions disabled until
plasma START signal released
CNC sending a
Hold?
Hold signal
still being sent?
• Solid state ignition ON
• Choppers 1&2 output
pilot arc current
• Gas console displays XF
• All functions disabled until
plasma START signal is released.
• Solid state ignition OFF
• Control board receives arc transfer
signal from Analog board
• Choppers 3&4 ON
• Start counter output is active
• After 100 ms, pilot arc relay OFF
• Power supply sends arc transfer signal to CNC
• Plasma gas switches from preflow to cut-flow
• Control board looks for pierce complete signal
• Shield gas switches from preflow to cut-flow after pierce complete
• All choppers ramp up to set output current
• Control board monitors chopper output
All choppers ramp up
to 100A total output
Arc transfer within 300 ms?
All choppers ramp up
to 200A total output
Set current level > 200A?
Ye s
Ye s
Ye s
Ye s
System in RUN mode
Next
Page
No
No
No
No
Phase loss detected?
• Main contactor CON1 OFF
• Gas console displays PL error
• All functions disabled until
plasma START signal is released
Ye s
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