Schumacher 120V - Manual (Page 18)

CONNECT WELDER GROUND
Attach the ground clamp to the work piece making sure that the work piece is cleaned of dirt, oil, rust,
scale, oxidation, and paint at the point of connection. It is best to connect the ground clamp directly to
the work piece and as close to the cut as possible. If it is impractical to connect the ground clamp
directly to the work piece, connect it to metal that is securely attached to the work piece, but not
electrically insulated from it. It is possible to cut ungrounded pieces, but cutting capacity is limited and
consumable life is decreased.
CAUTION!
RISK OF ELECTRONIC COMPONENT DAMAGE!
If the ground clamp is being connected to an automobile or other equipment with on-board computer
systems, solid state electronic controls, solid state sound systems, etc., do not cut until disconnecting
the cable from the battery that is attached to chassis ground. Failure to do so may result in electronic
component damage!
OPERATION
ARC STARTING
When the trigger is pressed, compressed air flows through the torch. When it reaches the end of the
torch, the electrode is pushed back away from the nozzle by the force of the air. When the gap
between the electrode and nozzle becomes great enough, an arc is created and quickly becomes a
plasma arc.
DUTY CYCLE
The duty cycle rating is expressed as a percentage of an industry recognized cycle, based on a 10
minute working time period. The duty cycle rating of a plasma arc cutter tells the operator what portion
of the 10 minutes of working time the cutter can be used for cutting and what portion of the time the
cutter must be allowed to rest and cool. Your unit has a duty cycle rating of 35%. This means that out
of the 10 minute working time period, you may cut for three and one half minutes, but must allow the
cutter to cool for the remaining six and a half minutes of the working time period.
SAFETY INTERLOCKS
When air pressure is not sufficient to blow the electrode back from the nozzle, current will not be
allowed to the torch for cutting. Some common reasons for low air pressure are:
1. The compressed air source pressure or the air regulator on the cutter is set too low.
2. The consumable parts at the end of the torch are not installed at all or not installed properly.
3. Any filter being used with the cutter is plugged and needs to have a new filter element
installed.
4. A thermal switch is also provided in the cutter to prevent overheating. Exceeding the cutter
duty cycle rating, or holding the torch more than 1/16 inch from the workpiece normally
causes overheating.
For all of these conditions, an error message will be indicated on the digital display or the LEDs on
the unit to indicate the problem.
GENERAL MAINTENANCE
This plasma arc cutter has been engineered and manufactured to give many years of trouble-free
service providing that a few very simple steps are taken to properly maintain it.
1. Inspect and replace all cutting torch consumables in a timely manner.
2. Periodically, unplug the power cord from the ac power source and remove the cover from the
plasma cutter. Air-blow any accumulated dust and dirt from the inside of the cutter and reinstall the
cover. Initially, this should be done after the first six months of operation. After that, do it more or less
frequently depending on what your cutter's environment dictates.
Always check that the torch consumables are in good shape and not worn out. This is the biggest
single thing to assure the best cutting performance.
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