A high voltage a. c. arc source unit of usual type was constructed in order to develop the spectrochemical methods of trace elements in iron and steel. This arc supply consists of a power transformer having a 220 volt primary and two 2200 volt secondaries, each capable of supplying 2.2 amperes. A switching system allows the secondaries to be hooked inseues or parallel, so that two voltage ranges are available; 2200 and 4400.
Seventy heater type coils wounded by 0.5 mm “Advance” wire are used as a ballast resistors in the secondaries and permit one to control the current from ampere to ampere at 4400 volt range and from to ampere at 2200 volt range.
The arc stand in locked into safety cage and the door of this cage act, as a switch preventing the current to flow into trasformer primary when this door is opening.
