V.R.D  "Voltage Reduction Device"  is a safety system found on our Digital range of TIG welders which have MMA ARC Welding Function.
Normal O.C.V (Open circuit voltage) is between 70-95 volts DC, when the machine is put in MMA mode it is constantly LIVE so if you touch the stick electrode onto workpiece it would stike an arc immediately.
When V.R.D is turned on the OCV is lowered to 20V (+/- 3v) so is much safer, especially when long welding cable are used.
Once the arc electrode has touched the workpiece the weld arc starts and welding carries on as normal.
When welding in V.R.D mode you may experience a slight delay in arc starting, the is normal.
It can be slightly harder to strike an arc on very rusty / dirty materials so you may have to scratch harder or clean the metal before welding.