Lincoln Electric 355M, 405M service manual Negative Electrode Polarity, Voltage Sensing

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A-5 INSTALLATION A-5

UNDERCARRIAGE MOUNTINGS

CAUTION

MOUNTING HOLE LOCATIONS	Excessive voltage drops	caused	by poor work
NOTE: MOUNTING SCREWS CAN NOT PROTRUDE MORE THAN
0.5 INCHES INSIDE THE MACHINE.	piece connections often result in unsatisfactory
3.50	welding performance.

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1/4-20 NUT (4 PLACES)	NEGATIVE ELECTRODE POLARITY
	When negative electrode polarity is required, such as
5.50
	in some Innershield applications, reverse the output
10.00	connections at the power source (electrode cable to
	the negative (-) Twist-Mate terminal, and work cable
	to the positive (+) Twist-Mate terminal.

11.84 4/01

M19527

OUTPUT CABLES, CONNECTIONS AND LIMITATIONS

Connect a work lead of sufficient size and length between the proper output terminal on the power source and the work. Be sure the connection to the work makes tight metal-to-metal electrical contact. To avoid interference problems with other equipment and to achieve the best possible operation, route all cables directly to the work or wire feeder. Avoid excessive lengths and do not coil excess cable.

CAUTION

When using inverter type power sources like the Power Waves, use the largest welding (electrode and work) cables that are practical. At least 2/0 copper wire - even if the average output current would not normally require it. When pulsing, the pulse current can reach very high levels. Voltage drops can become excessive, leading to poor weld- ing characteristics, if undersized welding cables are used.

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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 Twist-Mate terminal on the power source. 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 con- tact. The electrode cable should be sized according to the specifications given in the output cable connections

section. Connect a work lead from the negative (-) power source output Twist-Mate terminal 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.

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 PowerWaves have accurate data about the arc condi- tions. 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.

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.

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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. By default the WORK voltage is monitored at the output stud in the POWER WAVE 355/405. For more informa- tion on the WORK sense lead (21), see"Work Voltage Sensing” in the following paragraph.

POWER WAVE 355M/405M