Keithley 2231a 30 3 triple output variable bench dc power supply keithley 2231a 30 3 p the keithley 2231a 30 3 is a triple channel dc power supply that can output a total of 195w of power providing the power levels needed to energise a wide range of circuits and devices for bench top work p p two channels can supply up to 30v at 3a each the third channel can provide up to 5v at 3a the 2231a 30 3 does not compromise on performance or convenience features offering the versatility and e