Training Information
Sequence of Operations
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Gas Preflow
Removes residual moisture and contamination Allows gases to reach
proper flow in plasma chamber Usually lasts 2-3 seconds
Power supply is enabled
Open circuit voltage (OCV) is the maximum output voltage of power
supply, usually 200-400 VDC. Enabled by pilot contractor or pilot
relay often designated PCR or CR-1
Created voltage potential between electrode and nozzle Pilot resistor
limits current flow between electrode and nozzle.
High frequency
High voltage 5-12,000 VAC (Like a bug zapper). Usually generated
by HV transformer, capacitors, and spark gap assembly. Breaks
down high pressure gap between nozzle and electrode. Establishes
path for DC current flow. Remains on until arc transfers to plate
or "times out".
Pilot arc = gas + HF (AC) + DC (limited)
DC "superimposed over high frequency AC.
10-50 amps limited by pilot resistor.
Should be a steady blue flame that will sustain itself in the
air.
Forms the electrical pathway to the workplace.
Strength of the pilot are determines the transfer distance and
starting reliability.
Too much piloting causes short part's life.
Transferred arc = gas + full DC output
If the pilot arc is within transfer distance, the arc attaches
to the plate.
Power supply "senses" arc transfer (DC current flow to plate),
pilot relay opens.
Pilot shuts off.
Power supply brings DC power output up to current settings.
Piercing or cutting begins.
Stage 1 of pierce
Stage 2 of pierce
Stage 3 of pierce
