CLOSE SPEED CONTROL IS KEY

Key to the savings is the close speed control of fans and pumps, using AC drives from Control Techniques, matching supply with demand and reducing the cooling plant power consumption, when idling, to about that of a domestic kettle.

The new SPX Marley highefficiency cooling tower has two 30kW cooling fans for the dual 300m3 cells and there are six large pumps – three 22kW pumps for the hot water to the tower and three 90kW, 4.4 bar pumps to return the chilled water back to the factory. All fans and pumps are fitted with Control Techniques Commander SK AC drives, each of which receives a speed reference from the controlling PLC system that monitors pressure, temperature (of cooled water), levels in the cooling water sumps, etc., and which also produces trend predictions.