Arc Machines 207 - Manual (Page 12)

MODEL 207A AND 207A-1
OPERATION MANUAL
Doc. No. 740044
Rev F
SECTION I - INTRODUCTION
1.3 SHOCK HAZARD WARNING
As already stated in this manual “High Voltage” is present on exposed internal
terminals. The ELECTRODE (tungsten and M-9 rotors) is also an “exposed
terminal” and by its nature the GTAW process requires electrical potential to be
present on the electrode during arc starting and of course during the welding.
All AMI Power Supplies contain a “bleeder” circuit to ground any residual
potential after welding or after an aborted or bad “arc start” attempt. However,
these circuits take a few seconds to operate or COULD FAIL.
“THE ELECTRODE SHOULD ALWAYS BE CONSIDERED A POSSIBLE
SHOCK HAZARD”. This is especially true when ever the system is in “weld
sequence” ready to weld, is welding or has just finished welding. However,
equipment/component failure, system abuse, or improper maintenance could
result in electrical potential at the weld head “even when not in weld sequence”.
The users/operators of this equipment must take all precautions necessary to avoid
contact with the ELECTRODE at “ALL TIMES”. The only exception is when
actually replacing or adjusting the electrode and this should be done “WITH THE
POWER TURNED OFF”.
If performed with the power “ON” the system must be in test mode out of weld
sequence and the USER MUST OBSERVE COMMON SAFETY PRACTICES
such as grounding the electrode to insure discharge before actually touching it.
REMEMBER, there is a “POSSIBLE” shock hazard in all welding power supplies
at “ALL” times.
Most AMI Power Supplies feature High Frequency (HF) Arc Starting. This is a
High Voltage/High Frequency electrical transmission process. To eliminate any
HF shock possibility “AVOID ALL CONTACT” with the Welding WORK
(ground), the ELECTRODE or the WELD HEAD during arc start.
1.7