In the early 1960s, Castell provided interlocks to the power station; more than half a century later, the interlocks are still performing well. When the station was due to add a north bank extension, project owner Zambia Electricity Supply Corporation (ZESCO) recommended Castell to the project contractor SINOHYDRO.

Castell’s interlocks force workers to follow a predetermined process when operating or maintaining machinery and equipment, to prevent human error and safeguard workers’ access to dangerous areas.