Electronics Production | August 22, 2006
Nothing wrong with AEG's UPS at Swedish nuclear power plant incident
AEG Power Supply Systems GmbH (AEG PSS) released its report to Forsmarks analyzing the behaviour of the UPS (Uninterruptible Power Supplies) units that were involved in the incident at the nuclear power plant on July 25th 2006.
On the basis of tests and simulations conducted since the incident, the report shows clearly that the UPS worked within the parameters that had been specified initially for over and under voltage conditions. The original parameters were set according to specifications. As part of the recent tests and simulations, AEG Power Supply Systems engineers demonstrated that adjusting these parameters in combination with the response time would allow the system to withstand such short circuits. “As soon as we were informed of the situation, the company fully committed itself to an in-depth investigation, in close coordination with Forsmarks, said Karl-Heinz Schulz, Managing Director of AEG Power Supply Systems. An AEG expert team was immediately sent onsite to analyze the UPS units affected. At the same time, technical specialists carried out in-house tests to simulate the Forsmark conditions during the short circuit and to analyze the response of the UPS systems under these abnormal conditions. These tests showed that the systems performed normally within the voltage limits. This means the UPS systems transfer to bypass, as normal safety behaviour, due to over voltage exceeding the settings' values. On the basis of these conclusions and new requirements from Forsmarks, the parameters of the device have been set in a way to react appropriately to larger voltage variations and notably to better withstand sudden voltage peaks. “We are pleased that our equipment performed normally, and that recommendations could be made quickly and efficiently” said Schulz. The UPS units for the Forsmark 1 plant were provided by the former AEG group in 1993. Hundreds of these UPS have been sold since then, but no system can be compared to another, as these UPS are customized to customer needs and specifications. “We want to make absolutely clear that the configurations of our systems installed in German power plants are different, because the overall security systems are different and because environment and product specifications are different,” added Schulz.