Lincoln Electric POWER WAVE STT Operator's Manual page 7

Remote Sense Lead Connections
Voltage Sensing overview
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The STT welding process requires the use of remote
voltage sense leads to more accurately monitor the
conditions of the arc. These leads originate in the power
source, and are connected and configured external to
®
the STT Module. Consult the power source instruction
manual for detailed information.
Note:
Other processes run through the STT
necessarily require sense leads, but will benefit from
their use. Consult the power source instruction manual
for recommendations.
General Voltage Sensing Considerations for
multiple arc Systems
Special care must be taken when more than one arc is
welding simultaneously on a single part. The placement
and configuration of remote work voltage sense leads is
critical to the proper operation of multiple arc STT
applications.
RECOMMENDATIONS:

Position the sense leads out of the path of the
weld current. Especially any current paths common
to adjacent arcs. Current from adjacent arcs can
induce voltage into each others current paths that
can be misinterpreted by the power sources, and
result in arc interference.

For longitudinal applications, connect all work
leads at one end of the weldment, and all of the
work voltage sense leads at the opposite end of the
weldment. Perform welding in the direction away
from the work leads and toward the sense leads.
(See Figure a.4)
Figure A.4
1. Direction of travel.
2. Connect all sense leads at the end of the weld.
3. Connect all work leads at the beginning of the weld.
English
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Module do not
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4
Bad connection

Current flow from Arc#1 affects Sense lead #2.

Current flow from Arc#2 affects Sense lead #1.

Neither sense lead picks up the correct work
voltage, causing starting and welding arc instability.
Better connection

Sense lead #1 is only affected by current flow from
Arc#1.

Sense lead #2 is only affected by current flow from
Arc#2.

Due to voltage drops across workpiece, Arc voltage
may be low, causing need for deviation from
standard procedures.
Best connection

Both Sense leads are out of the current paths.

Both Sense leads detect arc voltage accurately.

No voltage drop between Arc and Sense leads.

Best start, best arcs, most reliable results.

For circumferential applications, connect all work
leads on one side of the weld joint, and all of the
work voltage sense leads on the opposite side, such
that they are out of the current path.
English