Not only relays tests and laboratory tasks depend on accurate and reliable power sources but many other application areas as well. The power source ST40A is characterized by its high precision with makes it suitable not only for relay testing but also for calibration tasks with surrounding temperatures of up to 50 ° C. As a voltage-generator in 3-phase operation, the adjustable voltage ranges from 0 to 150V at a resolution of 10mV. As a current-generator, the resolution is 5mA. The generators can be operated with a nominal voltage of 110Vac to 240Vac with a nominal frequency of 50 and 60Hz. The easy handling and operation of the devices is ensured through a color LCD. There are 4 binary inputs and the sources can be connected via a USB connection to a PC.