10Ap1 Tig Board; 10Ap1:1 Power Supply; 10Ap1:2 Communication With The Control Board; 10Ap1:3 Gas Valve - ESAB Origo Mig L3000i Service Manual

5 DESCRIPTION OF OPERATION
5.3

10AP1 Tig board

The TIG board is fitted to the Tig 3000i and Tig 3000i AC/DC. Sections 10AP1:1 to 10AP1:5
refer to the wiring diagrams in "10AP1 Tig board", page 27.
Circuit diagram of the TIG functions
5.3.1

10AP1:1 Power supply

42 V AC is supplied from transformer 2TC1.
5.3.2

10AP1:2 Communication with the control board

The processor on circuit board 20AP1 controls the gas valve and the HF generator.
The processor senses the start signal from the torch switch when optocoupler IC1 is
energized.
5.3.3

10AP1:3 Gas valve

When the torch switch is operated, relay RE1 closes and energizes the gas valve. When the
torch switch is released and the gas post-flow time has elapsed, the gas valve is deactivated.
5.3.4

10AP1:4 HF generator

When the welding torch switch is operated, and the open-circuit voltage is over 50 V, relay
RE2 closes and turns on the HF generator, TR1. It remains activated until the arc strikes, or
for a maximum of 0.7 seconds.
The voltage on the primary side of HF transformer 10TV1 is about 550 V. The secondary
voltage is about 11 kV if a 4 metre long welding torch is connected. If the welding torch is 16
metre long, the HF spark is about 8 kV.
Due to electromagnetic interference regulations, the energy in the HF ignition spark is
limited, and so the HF spark weakens with increasing length of the torch. The HF ignition is
satisfactory for welding torches up to 16 metres.
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