Lincoln Electric Making Fillet Welds manual Square Wave vs. Sine Wave, Square Wave Balance

W A V E F O R M C O N T R O L T E C H N O L O G Y T M

APPLICATION

Making Fillet Welds with Power Wave AC/DC 1000™ System	3/10
Welding Guide

Square Wave vs. Sine Wave

Figure 2 shows one cycle of a true 60 Hz sine wave with a square wave superimposed upon it. Note that while the rms2 value and the peak values are the same for both waves, the transition time for peak-to-peak is much shorter for the square wave. The transition period is what has always caused instability with conventional AC welding but with the rapid transition associated with the Power Wave AC/DC 1000™, arc stability is increased.

Square Wave Balance

Square wave balance can allow the arc to act more as a DC negative or DC positive arc, thus increasing deposition rate or increasing penetration. This is always expressed as a percentage of the DC + component. i.e., (25% Balance means that only 25% of the cycle will be positive while 75% of the cycle will be negative, etc.)

Figure 3 shows two 3/8” (10mm) flat positioned fillet welds. Both were made at 814 amperes but the square wave AC 25% balance wave is made 17% faster.

Figure 4 graphically shows the significance that square wave balance can and does play. Note that only 25% of the time is the arc positive while 75% of the time

it is negative. This flexibility can be used to tailor the arc to achieve best results by increasing deposition, decreasing penetration or decreasing deposition and increasing penetration.

SINE WAVE

SQUARE WAVE TRANSITION

TRANSITION REGION

REGION

+ VOLTS

0

- VOLTS

1CYCLE 1/60 SECOND

60 Hz SINE WAVE vs 60 Hz SQUARE WAVE

Figure 2

DC+ AC 25% Balanced

Figure 3

Figure 4

2Rms: root-mean-square value of current or voltage. For example, when someone refers to, “110 volts,” this is actually an rms value as is “30 volts AC”, etc.

T h e f u t u r e o f w e l d i n g i s h e r e . ®