Test Results of 60 kVA Current Limiting Transformer With Full Recovery Under Load

Superconducting fault current limiting transformers (SFCLT) in electrical power systems offer the possibility to have both high short-circuit power during normal operation and limited short-circuit currents under fault conditions. During the current limitation, the temperature of the superconductor increases because of the resistive losses until the short-circuit is switched off. After the current limitation, the superconductor has to cool down to become superconducting again. Recovery under load is a very important requirement for superconducting current limiting transformers because in many applications it is not allowed to interrupt the power supply. In this case the superconductor has to cool down under regular load conditions. This paper presents the test results of a 60 kVA current limiting transformer demonstrator with full recovery under load. The design and the test results of the demonstrator are shown in detail and the test results confirm that full recovery under load can be achieved.