L-TEC PCM-70 - Operation

(Nitrogen to PLASMA GAS fitting; nitrogen, air, or
CO2 to COOLING-GAS fitting). Connections should
be wrench tight.
f. Electrically connect work cable to work piece. The
connection must be made to a clean, exposed metal
surface free of paint, rust, mill scale, etc.
WARNING
A poor connection or failure to connect work cable to
Work piece can result in fatal shock.
g. Make sure workpiece is connected to an approved
earth ground. Use copper ground cable equal to or
larger than the power supply chassis ground listed in
Table 6.
V. ADJUSTMENTS & OPERATIONS
CAUTION: Never, under any circumstances, operate the
power supply with the cover removed. In addi-
tion to the safety hazard, improper cooling may
cause damage to internal components. Keep
side panels and top closed when unit is ener-
gized. Also make sure you are adequately
protected before you start cutting — protective
helmet and gloves should always be worn.
Refer to page 2 for additional operating precau-
tions.
CAUTION: Voltage is available at the POWER On-Off
switch on the hinged top cover when voltage is
applied to the input terminal board even when
the POWER switch is OFF.
A. TORCH ADJUSTMENTS
WARNING
Before making any adjustments or performing any main-
tenance on the torch, make sure the power to the torch is
shut off and the "Torch On" light is off. Do NOT make any
adjustments underneath the hinged top of the unit unless
the primary power to the unit is OFF even if the Power
on-off switch is off.
For torch adjustments, see booklet F-12-794 (PT-121) or
F-14-441 (PT-17A) packed with the torch.
B. PCC-70 ADJUSTMENTS
1. Slowly open the nitrogen and CO2 or air cylinders val-
ves.
2. Place the PCC-70 OPERATE/SET-UP and POWER
switches in the SET-UP and OFF positions.
. Place the primary (wall) switch in the ON position.
4. Place POWER SWITCH to ON POSITION. "Low Gas"
light should light up. (This light is indicating that power
is applied to the control circuit.) Fan should be running.
Wi
5. With OPERATE/SET-UP switch in SET-UP position gas
solenoid valves should be open. Adjust the gas
regulator(s) to deliver proper pressure (Tables 3 & 4).
6. Allow the gases to flow for a few minutes. This should
remove any condensation that may have accumulated
during shut down.
7. Place the OPERATE/SET-UP switch in the OPERATE
position. This will shut offthe gas flows. (The *Low Gas"
will remain on. It will go off when torch switch is
depressed and it will then function as a low gas indicator
light.)
C. OPERATION
ARNING
Wear the usual protective gloves, clothing, and helmet.
Helmet with filter lens shade No. 6 or 7 should provide
adequate protection for your eyes.
Never touch any parts forward of the torch handle (tip,
heat shield, electrode, etc.) unless the Power switch is in
the OFF position.
1. Position the PT-17A or PT-121 torch on the workpiece by
resting the heat-shield on the edge of the workpiece
where you intend to start the cut.
2. Lower your protective helmet and then lift the torch
about 1/8-in. above the workpiece.
3. Push down on the torch switch button mounted on the
torch handle. Pilot arc contactor and high frequency will
energize, and gas will start flowing. Two seconds later,
the main contactor will come on. The pilot arc should
then transfer to the cutting arc.
NOTE: If cutting arc does not start within 6 seconds, the
pilot arc will shut off. Release torch switch. Check to
be sure gas pressures are adequate, work cable is
firmly connected to workpiece, torch was about 1/8
to 1/4-in. above workpiece, etc. Then start from step
1 again.
4. For manual cutting, maintain a standoff (torch-to-work
distance) of about 1/8 to 3/8-in. (3/16 to 1/4-in. with the
PT-121). (See Table 3 or 4.) Keep the torch head vertical,
and move it at a rate that produces the desired cut
quality. The cutting should produce a straight fine spray
of molten metal emitting from beneath the workpiece as
illustrated in Fig. 5. For mechanized cutting, see Table
3 or 4 for recommended cutting speed range.
5. If cutting arc is lost during cut, the pilot arcimmediately
reignite as long as the torch switch is depressed. You
then have about 6 seconds to move the torch close
enough to work to reestablish the cutting arc.
6. The cutting arc will extinguish at the end of the cut;
however, the torch switch should be released to keep the
pilot arc from reigniting.
7. When cutting operation is completed, wait a few
minutes before placing the POWER switch to the OFF