Tweco PCM-120 Machine Torch - Manual (Page 56)

APPENDIX A-6 Manual 0-2698
APPENDIX 2: SEQUENCE OF OPERATION BLOCK
DIAGRAM
ACTION
ON/OFF switch
to OFF
RESULT
All indicators off.
Fans off.
ACTION
RUN/SET switch
to RUN.
RESULT
Gas flow stops.
GAS indicator off.
Power circuit ready.
ACTION
Torch moved within
transfer distance of workpiece.
RESULT
Main arc transfer.
Pilot arc off.
DC indicator still on.
ACTION
Torch deactivated (by torch switch
release or by remote device).
RESULT
Main arc stops.
(Power supply enable signal removed.)
DC indicator off.
NOTE - If torch is activated during
post-flow, pilot arc will immediately restart.
If torch is within transfer distance (3/8 in) of
workpiece, main arc will transfer.
After post-flow:
Gas solenoids close, gas flow stops.
GAS indicator off.
ACTION
Open external
disconnect.
RESULT
No power to system.
ACTION
Close external
disconnect switch.
RESULT
Power to system.
ACTION
RUN/SET switch
to SET.
RESULT
Gas solenoids open,
gas flows to set pressure.
GAS indicator on.
ACTION
Torch moved away
from work (while
still activated).
RESULT
Main arc stops.
Pilot arc auto-
matically restarts.
PILOT ARC
ACTION
ON/OFF switch
to ON.
RESULT
AC indicator on.
Pilot disabled during
pre-flow.
Fan on.
ACTION
Protect eyes and
activate torch
RESULT
Gas flows
GAS indicator on
After gas pre-flow:
DC indicator on.
Power supply enabled.
HF enabled.
Pilot arc established.
A-02194