In late 2022, CONDIS embarked on the journey to break several of its internal records and achieve a world first. The company won the tender to produce an 800kV Low Power Voltage Transformer (LPVT), more specifically a Resistive Capacitive Divider.
This mini-series takes you through the various stages in the design and construction of the 800kV from the perspective of the different people involved in the project. In this first chapter, Thomas Heid, Product Engineering Manager at CONDIS, answers our questions about the research and development phase.
What were the most stringent requirements set forth by the end user for the design and how did you work with the end user to meet or adapt them?
“One of the more challenging requirements was the need for an accuracy class 0.1 for this 800kV RC-divider (LPVT), with less than 1% permitted ratio error for the extended frequency range, which is much more restrictive than the error limits defined for class 0.1-WB2 in IEC 61869-1 Ed.2.
These accuracy requirements need to be maintained for the full temperature range of -50°C up to +40°C, both in the cold state of the divider, as well as after its thermal stabilization. This guarantees that the LPVT remains in accuracy class both after its energization from a cold state, as well as during its long-term operation.”
“Due to the size of 800kV electrical equipment, testing the real size LPVT under nominal voltages and over the full temperature range is next to impossible. Hence, we designed a scaled model of reduced size, which allowed us to fully test all critical parameters with representative primary voltages and the full temperature range. These results, combined with analytical approaches, allowed us to optimize our design and validate the performance of the full-scale product.
Besides this, there were several other requirements by the customer, which derived from our standard LPVT products and their utilization. In order to help the customer validate feasibility, we further performed a series of additional testing using the scaled prototypes, as well as the full-scale 800kV RC Divider.”
