Tweco Thermal Arc TA 500 - Manual (Page 29)

Manual No 0-0470 3-3 Operation
3.2 Pre-Operation Set-up
This procedure should be followed at the beginning of each
shift:
WARNING
Check to be sure main disconnect switch is open.
1. Check the coolant level in the Coolant
Recirculator and fill to proper level if necessary.
2. Check the torch to be sure it has the proper com-
ponents and is assembled and adjusted cor-
rectly.
3. Close the main disconnects supplying 3-phase
power to the Power Supply, Coolant
Recirculator and Hi-Flow Water Shield (if used).
4. Turn the ON/OFF switch on the Control Panel
to ON. The Coolant Recirculator will come on.
The amber READY light will come on. (If the
gas supply is on, the gases will flow for 2 sec-
onds).
5. Select the plasma gas pressure for the type of
cutting to be done from Table 3-B. Move the
RUN/SET/PURGE switch to the SET position.
Open the plasma gas supply valve at the source.
Adjust the pressure regulator on the gas sup-
ply until the plasma pressure selected from the
Table is obtained.
6. Move the switch to PURGE for approximately
3 minutes (this allows the plasma gas to run).
This will remove any condensation or moisture
that may have accumulated in the torch while
it was shut down. If there is any sign of mois-
ture after purging, determine the cause and
correct it before operating the system.
NOTE:
Only the plasma gas needs to be purged.
7. Return the RUN/SET/PURGE switch to the
SET position and open the secondary supply
valve at the source. Adjust the pressure regu-
lator at the gas supply until pressure reads 60
psi (4.1 bar) or turn on the secondary water if
water shield cutting and set at about 12 gph.
8. Return the RUN/SET/PURGE switch to the
RUN position.
9. Set the CURRENT ADJUST knob on the Con-
trol Panel for desired amperage level.
10. Check the position of the HI-FLOW WATER SHIELD
ON/OFF switch and the PILOT AUTO/MAN switch
on the Power Supply for desired operating mode.
Surface or Underwater Cutting
11. The two cutting modes, Surface and Underwater, re-
quire a different pilot resistance. This is easily se-
lected using the SURFACE/UNDERWATER switch
on the TA500. The M200 torch also requires differ-
ent parts for underwater operation. Refer to Section
4.1 for details.
Bevel Cutting
12. Bevel cutting requires a greater standoff distance
due to the angle of the torch. The pilot resistance
therefore must be changed to ensure that the main
arc will transfer and that proper standoff will be found
when using an SC504 Standoff Control. The proper
resistance for surface bevel cutting is obtained by
moving the SURFACE/UNDERWATER switch to the
UNDERWATER position.
When bevel cutting, underwater resistance value of
the pilot resistor (R2) must be adjusted. Consult the
Thermal Dynamics Customer Service Department for
assistance in obtaining the correct resistance value.
The system is now ready for operation.
3.3 Operation
WARNING
Be sure the operator is equipped with proper
eye and ear protection and that all precautions
in the front of this manual have been followed.
1. The M200 torch must be at right angles to the plate
to obtain a clean, vertical cut. Use a square, as shown
in Figure 3-F, to align the torch.