Accelrated Life Testing of Muktijunction Thermal Converters with a Microcontroller

Multijunction thermal converters (MJTCs) used as AC-DC transfer devices are the most accurate wideband standards for precision AC measurements. Due to their high accuracy and broadband capability, MJTCs are used as the primary standards for AC-DC difference metrology at the National Institute of Standards and Technology (NIST). To determine the useful lifetime of these devices, a microcontroller test was designed to stress an MJTC under its routine operational conditions over an extended time period. This paper illustrates the long-term stability and accuracy maintained by the MJTC when operated within its specified parameters. Results indicate the lifespan of these reference instruments extends beyond 90 years for devices averaging 4 cycles per workday over the duration of a year.