Arc Machines 227 - Manual (Page 14)

MODEL 227
OPERATION MANUAL
Doc # 740063 Rev E
SECTION I - INTRODUCTION
1.3 RF AND EMI TRANSMISSIONS
3. RF PROTECTION (continued)
Most RF noise interference problems are going to be either set-up related or
caused by poor or no filtering on the behalf of the equipment that is being
interfered with. Most problems are easily correctable but each one must be
looked at on a “case by case basis.”
4. EMI SUPPRESSION
The M-227 is equipped with a heavy-duty Pi-Network filter, connected to
the input power line, to prevent propagation of EMI either into or out of the
M-227. The all-metal enclosures and internal shields prevent radiated EMI.
1.4 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.
1.8