Fully automated test system for the Thermal Stability Test of surge protective devices according to IEC 61643-1

Varistor-based surge protective devices (SPDs) for low voltage power distribution systems are equipped with a disconnect device, which disconnects the SPD from the power supply in case of thermal overload. The standard IEC 61643-1 describes a test to prove safe behaviour of these kinds of SPDs in case of rising leakage currents. This test is called Thermal Stability Test and its focus is set to proof reliable function of thermal activated disconnection devices. The test lasts commonly several hours and usually it is carried out manually. This is because of the fact that automated test systems are not available on the market up to now. Manual operated tests cause high economic efforts. Above that, the required precision of the test parameters demanded by the standard can not be achieved continuously by manual control. Therefore, the development of a fully automated test system for the Thermal Stability Test is attractive. The work presented, provides the detailed technical description of a fully automated test system which includes the control structure, the used hardware and the mechanical design of the test chamber. The performance of the test system and its advantages compared to manual operated tests are shown in case studies.