Prior power supplies have made use of current-limiting circuitry.  For example, U.S. Pat.  No.  5,457,364 discloses an electric motor driver with a current-limiting mechanism.  However, no known prior art power supply system has made use of an in-circuit method of rapidly testing whether the current-limiting circuitry was functioning correctly.  In order to test whether the current-limiting circuitry was properly cutting back current at the appropriate value, external equipment, such as voltage and/or current probes, needed to be attached test the power supply. 
It is also known that electric motor systems have employed mechanical torque limiters.  However, such torque limiters are unreliable, take up space, are heavy, and/or are not cost effective.  Further, the functionality of such systems cannot be easily verified in the field.