Patent ID: 6495932
Filing Date: 2002-12-17
Classification: G01R

Abstract:
A DC power source unit for supplying DC voltage to an electrically powered tool, the DC power source unit comprising:a main unit that has an output and produces DC voltage from the output; an adapter plug that is electrically coupled to the electrically powered tool in use; a connector that is electrically connected to the output of said main unit; an output cable having one end attached to said adapter plug and another end attached to said connector; output voltage setting means, provided in said adapter plug, for setting a level of voltage to be supplied to the electrically powered tool, the level of voltage set by said output voltage setting means corresponding to a rated voltage of the electrically powered tool; load current detection means for detecting an instant load current flowing in the electrically powered tool and outputting a detection signal indicative of the load current; output voltage changeover means for changing over the level of voltage to be supplied to the electrically powered tool in response to the level of voltage set by said output voltage setting means; and control means for controllably transmitting the level of the voltage set by said output voltage setting means to said output voltage changeover means, based on whether the detection signal output from said load current detection means indicates that the instant load current is equal to or less than a predetermined load current.