Specifications

1. The operator engages the torch switch on the torch, requesting a cutting operation. This closes

the torch switch connection at the control PCB (P5-1, P5-2). This enables the torch switch circuit, which,

ultimately, sends two logic signals out of that circuit. One signal leaves IC1-4 to enable the control chip

IC2 on PCB-1. The other signal leaves IC9-5 destined for the current control logic chip IC10 –1 via D22.

The start LED, LED1, lights up indicating start voltage is present. See Section 5.8.2.

2. The gas ow solenoid is engaged and air moves through the torch.

3. The Flow Switch closes.

4. After a 2 second preow delay, PCB1 relay K1 closes sending 115 VAC out to the HF circuit. The

Spark Gap unit, SG, engages.

5. IGBTs’ are gated on and open circuit voltage is available at the torch

6. The operator brings the torch nozzle in contact with the work surface

7. The HF signal ionizes the air and sets an environment conducive to main arc creation.

8. Main arc is established.

SECTION 3 SPECIFICATIONS

3.3 Sequence of Operation

NOTES:

1. When the torch switch is pushed during postow period, the postow and preow times are canceled, and the HF is

energized immediately.

2. When the red fault light comes on, cutting operation should be stopped. The postow time starts from the moment the

torch switch is released.

SEQUENCE OF

OPERATION

Trigger LOCK “UNLOCK” position (Applies to PT-21AMX and PT-32EH Torches)

Torch Switch

Gas Solenoid Valve

Flow Switch

Fault Overload Light

HF Circuit

Pilot Arc

Inverter

Cutting Arc (Current)

Energize

Open

Postow

Push

Open

2 sec.

Preow

Release

20 sec.

3.3 Sequence of Operations

SECTION 3 SPECIFICATIONS

CONTENTS