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MacGregor Welding Systems - Welding Products and Solutions

What is HFDC ?

HFDC (High Frequency Direct Current) is an unusual abbreviation which refers to a DC current with some associated  High Frequency ripple.

When choosing an HFDC power source, it is very important to consider the HF ripple levels as these dramatically effect the ability of a unit to accurately measure the welding process...


HFDC - Get what you set...

The HF content of a supply can represent an error in terms of what is set as the output compared to what is actually achieved.  

All MacGregor power supplies use full closed loop control to ensure you get what you set.

HFDC vs Capacitor Discharge

Be they advanced or otherwise, capacitor discharge machines commonly used for battery welding lack the output control inherent with closed loop HFDC.  Consequently, welding currents tend to rise faster than the physical material melting process leading to needless and dangerous sparking at the welding electrodes.  

Sparking equates to a poorly defined welding process due to material expulsion and causes rapid and excessive electrode wear.  

Those who take battery welding seriously should consider the long term cost and quality benefits of reduced electrode wear and a better defined process.  


Quality manufacture of  high value items such as battery packs demands quality in the long term.  Built in process monitoring provides a means to monitor and perfect the process.

HFDC - Does not mean an Inverter

Some HFDC welding supplies are simple electrical inverters which generally operate at fixed frequencies.  As such, these units will tend to superimpose proportionally much more HF ripple on top of the desired DC level.  


Since HF ripple tends to obscure the electrical process, it is very much more difficult to obtain tight process control monitoring with a basic inverter supply.


For general, wide process window welding this is not necessarily a problem, however when highly repeatable energy delivery is required, supported by close monitoring, the HF content from basic inverters can cause problems.

HFDC - Check the specifications

Operating frequency, ripple content and absolute accuracy at all power levels are important variables to consider when specifying a welding supply, particularly in applications where tight quality control is required.  

Look for High frequencies coupled with low ripple level content.  

HFDC - The ripple content

MacGregor HFDC supplies employ a unique and sophisticated multi stage switch mode system that is specifically designed to minimise the ripple content that exists at the output of a switch mode based welding supply.


The system is designed to maintain a constant level of ripple across all operating ranges of the machines, thereby giving predictable performance and clarity when measuring the electrical process.  


Ripple effects are further minimised by adjusting the ripple content frequency in proportion to the welding load. Typically operating frequencies range from 15Khz to 60Khz.  This leads to an output that is very near to an ideal pure DC output.

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