A-4

INSTALLATION
POWER WAVE 455/STT

A-4

CABLE INDUCTANCE, AND ITS EFFECTS

ON PULSE WELDING

For Pulse Welding processes, cable inductance will cause
the welding performance to degrade. For the total welding
loop length less than 50 feet, traditional welding cables may
be used without any effects on welding performance. For the
total welding loop length greater than 50 feet, the K1796
Coaxial Welding Cables are recommended. The welding loop
length is defined as the total of electrode cable length (A) +
work cable length (B) + work length (C) (See Figure A.3).
For long work piece lengths, a sliding work connection should
be considered to keep the total welding loop length less than
50 feet. (See Figure A.4.)
Output connections on some Power Waves are made via 1/2-
13 threaded output studs located beneath the spring loaded
output cover at the bottom of the case front.
Most welding applications run with the electrode being posi-
tive (+). For those applications, connect the electrode cable
between the wire feeder and the positive (+) output stud on
the power source (located beneath the spring loaded output
cover near the bottom of the case front). Connect the other
end of the electrode cable to the wire drive feed plate. The
electrode cable lug must be against the feed plate. Be sure
the connection to the feed plate makes tight metal-to-metal
electrical contact. The electrode cable should be sized
according to the specifications given in the work cable con-
nections section. Connect a work lead from the negative (-)
power source output stud to the work piece. The work piece
connection must be firm and secure, especially if pulse weld-
ing is planned.
When welding with the STT process, use the positive output
connection labeled “STT” for STT welding. (If desired ,other
welding modes can be used on this stud; however, the aver-
age output current will be limited to 325 amps.) For non-STT
processes, use the positive output connection labeled “Power
Wave”, so that the full output range of the machine is avail-
able.
Do Not connect the STT and Power Wave stud together.
Paralleling the connection will bypass the STT circuitry and
severely deteriorate STT welding performance.
For additional Safety information regarding the electrode and
work cable set-up, See the standard "SAFETY INFORMA-
TION" located in the front of the Instruction Manuals.
Excessive voltage drops caused by poor work piece
connections often result in unsatisfactory welding per-
formance.

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NEGATIVE ELECTRODE POLARITY
When negative electrode polarity is required, such as in
some Innershield applications, reverse the output connec-
tions at the power source (electrode cable to the negative (-)
stud, and work cable to the positive (+) stud).
When operating with electrode polarity negative the
"Electrode Sense Polarity" DIP switch must be set to the
"Negative" position on the Wire Drive Feed Head PC Board.
The default setting of the switch is positive electrode polarity.
Consult the Power Feed instruction manual for further
details.
VOLTAGE SENSING
The best arc performance occurs when the Power Waves
have accurate data about the arc conditions. Depending
upon the process, inductance within the electrode and
work lead cables can influence the voltage apparent at
the studs of the welder. Voltage sense leads improve the
accuracy of the arc conditions and can have a dramatic
effect on performance. Sense Lead Kits (K940-10, -25 or
-50) are available for this purpose.
If the voltage sensing is enabled but the sense leads are
missing, improperly connected, or if the electrode polar-
ity switch is improperly configured, extremely high
welding outputs may occur.

------------------------------------------------------------------------

The ELECTRODE sense lead (67) is built into the control
cable, and is automatically enabled for all semi-automatic
processes. The WORK sense lead (21) connects to the
Power Wave at the four pin connector located underneath
the output stud cover. By default the WORK voltage is moni-
tored at the output stud in the Power Wave 455M/STT. For
more information on the WORK sense lead (21), see "Work
Voltage Sensing”in the following paragraph.
All constant current processes sense the voltage at the out-
put studs of the POWER WAVE-455M/STT by default.
CAUTION
CAUTION
B
A
C
FIGURE A.3
POWER
WAVE
WORK
A
C
B
POWER
WAVE
FIGURE A.4
K1796 COAXIAL CABLE
MEASURE FROM END
OF OUTER JACKET OF
CABLE
C
A
B
WORK
SLIDING WORK CONNECTION
FIGURE A.4