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Pilot arc current levels -29 – Hypertherm HT4400 HySpeed Plasma Arc Cutting System User Manual

Page 120

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MAINTENANCE

HT4400

Instruction Manual

5-29

3

Start Circuit Board PCB14 - Status Indicators and Operation

See page 6-4 for location of Start Circuit Board.

Operation

The start circuit is a high-speed switch that quickly transfers the pilot arc current from the pilot arc load to the
work load. The start circuit performs 2 functions:

1. It allows the initial pilot arc current to flow through the pilot arc lead quickly, with little impedance.

2. After initial pilot arc current is established, the start circuit introduces impedance to the pilot arc load to

aid in transferring the arc current to the workpiece. See schematic on following page.

Pilot Arc Current Levels

The pilot arc current level will change depending on the chosen process and arc current level. See table below.

O2 as the Plasma Gas

Pilot Arc Current

100-amp current setting

30 amps

200-amp current setting

44 amps

300-amp and 400-amp current setting

60 amps

N2 as the Plasma Gas

Pilot Arc Current

200-amp current setting

44 amps

400-amp current setting

60 amps

D2
+15 VDC

D1
IGBT Output

J1