Lincoln Electric IM762-C manual Negative Electrode Polarity, Voltage Sensing

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 ft.(15.24m), tradi- tional welding cables may be used without any effects on welding performance. For the total welding loop length greater than 50 ft.(15.24m)), 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).

B

For long work piece lengths, a sliding ground should be considered to keep the total welding loop length less than 50 ft.(15.24m). (See Figure A.4.)

FIGURE A.4

B B

SLIDING WORK

K1796 COAXIAL CABLE

MEASURE FROM END

OF OUTER JACKET OF

CABLE

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 positive (+). For those applications, connect the elec- trode 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 con- nection 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 connections 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 welding is planned.

For additional Safety information regarding the elec- trode and work cable set-up, See the standard "SAFE- TY INFORMATION" located in the front of the Instruction Manuals.

CAUTION

Excessive voltage drops caused by poor work piece connections often result in unsatisfactory welding performance.

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

NEGATIVE ELECTRODE POLARITY

When negative electrode polarity is required, such as in some Innershield applications, switch the output connections 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 apparent voltage 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.

CAUTION

If the voltage sensing is enabled but the sense leads are missing, improperly connected, or if the electrode polarity switch is improperly configured, extremely high welding outputs may occur.

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

The ELECTRODE sense lead (67) is built into the con- trol cable, and is automatically enabled for all semi- automatic processes. The WORK sense lead (21) con- nects to the Power Wave at the four pin connector located underneath the output stud cover. By default the WORK voltage is monitored at the output stud in the Power Wave 455M. 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 output studs of the POWER WAVE-455M by default.