We were called to Harmony Goldmine – South Africa to ensure the safe start of a process critical water pump. The pump is 2100m underground, and was powered by a weak and unstable generator power supply. Since the water is pumped up, a soft stop must also be provided to avoid water hammer when shutting down.
In view of the unstable power supply from the generator supply, soft starters from our SI-HDN series with 6.6 kV/1.5 MW were selected. These devices are distinguished by a control structure that is specially designed for generator feeding and regulates fluctuations in the feed-in frequency and feed-in voltage over a wide range, thus allowing reliable operation under the required conditions. Furthermore, the ‘water hammer effect’ was successfully eliminated through the use of the soft stop function, thus preventing further damage to the infrastructure.