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
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
- 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
is a trademark owned by ZENA, Inc. for its welding systems and related products.
& Foreign Patents Pending
Copyright 1998,1999 by ZENA, Incorporated. All rights reserved.