What is high-frequency DC? I thought that DC meant unchanging voltage (like a battery)?

Your understanding of what is meant by the term DC is not correct. There seems to be a lot of confusion about just what the terms AC and DC mean.

In the field of electronics,

• AC is used as an abbreviation for the term Alternating Current which is a condition that exists at any time that electrical current flows in two directions within a given electrical circuit, with the number of the current reversals typically occurring at some predetermined rate over a given period of time.
• DC is used as an abbreviation for the term Direct Current which is a condition that exists at any time that electrical current flows in one direction only within a given electrical circuit (i.e., from a positive electrical potential to a negative electrical potential).

Direct current flow can have a number of forms:

• a constant electrical current (which would be the case where a constant electrical voltage flows in a single direction within an electrical circuit with a unvarying electrical load resistance), OR
• it can be constantly varying as the result of changes in supply voltage and/or electrical circuit resistance changes and/or electrical circuit load changes.

It is still Direct Current as long as the electrical current flow is in a single direction. Such current can vary in an infinite number of ways and still be DC as long as current flow in held to a single direction within the electrical circuit.

In the ZENA mobile welding system, the term high frequency DC (HFDC) has a very special meaning:

With the ZENA welding system, the term high frequency DC is used to describe a special condition where the direct current flow in the welding circuit (arc) is caused to vary, very slightly, in a special way, under electronic control, with the tiny variations happening at a very high speed, so as to produce greatly improved welding characteristics when compared to a conventional welding current generating system of the type used in standard engine driven welders, or in welders which use automotive alternators as welding current generators (which often refer to high frequency DC in their specifications).

In the ZENA welding system the high frequency current transitions / variations occur at least 18,000 times per second, and will typically exceed 21,000 times per second.

HFDC current provides a three very substantial benefits in the ZENA welders:

• HFDC creates electrical agitation of the welding puddle (you will hear a high pitched whistling/whining tone coming from within the puddle while you are welding). This puddle agitation process:
  • works to facilitate the removal of impurities from the weld puddle, and to
  • improve weld penetration by moving hot metal from the center of the puddle towards the edge of the puddle and cooler metal toward the center, allowing the arc to melt additional metal in the areas surrounding the puddle -- for a given current setting, and to
  • significantly improve over all weld quality by insuring that the metal which makes up the bead and the metal surrounding the bead are more homogeneously mixed with each other and that heat within the bead is more evenly distributed.
• HFDC also improves the ability of the welding cable to transmit DC welding power from the generator to your electrode -- reducing the effects of welding cable DC resistance and internal impedance -- allowing us, of a given welder, to use welding cable with a smaller cross sectional diameter than would other be necessary for proper welder performance
• HFDC also works to increase the stability of the welding arc and allows an operator to achieve excellent welding results with both a shorter than normal welding arc (down to 0", in many cases) OR a longer than normal welding arc (up to 2X welding rod diameter). Inexperienced welders find the welder to be much easier to use and with much better results than a conventional welder can provide -- pros find it much easier to create x-ray quality welds and, at the same time, find that top quality results take less effort.

For more on HFDC -- CLICK HERE

ZENA™ is a trademark owned by ZENA, Inc. for its welding systems and related products.

US & Foreign Patents Pending

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