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Case study

Clean water with flexible communication

Producing drinking water can be a complicated process, but in Halmstad on the Swedish west coast, it is surprisingly easy. In fact, the groundwater from the eskers of Halmstad is so clean that it is possible to use it directly as drinking water. To control the pumps transporting the water from the eskers, Halmstad Municipality uses drives and soft starters from CG Drives & Automation. Since they support communication by industriaI Ethernet both soft starters and drives can communicate with different networks in the water stations’ electrical cabinets.

[7 January 2013]

Prästjorden’s Water Station in Halmstad is one of the 17 water stations supplying Halmstad with drinking water. The water station pumps up 80 cubic meters of water every hour from a depth of 40 meters. The water goes directly into Halmstad’s drinking water without any cleaning at all. All that is added is some sodium in order to raise the water’s pH. However, given the large amounts of water, the sodium adding can be a time-consuming task. Magnus Winberg, coordinator at Halmstad Municipality explains: “Previously, we had to manually add nine bags of sodium each day. The new pump system handles this automatically which saves us a lot of work.”

Prästjorden’s Water Station, Halmstad. Through the pipe in Prästjorden’s Water Station, 80 cubic meters are pumped up every hour.


CG Drives & Automation’s products control the pumps

Halmstad’s water system use approximately 200 soft starters from CG Drives & Automation, making the pumps start and stop smoothly to minimize wear. In addition, 60 drives are used to set the exact engine speed for the pumps. The drives generate substantial power savings since it is possible to set the pump’s revolutions per minute (RPM) instead of running the engine at full speed and throttle the water flow.


Anybus CompactCom converts the signals from the network in the water station (in this case, Modbus-TCP) and make these signals understandable for the drives and soft starters used to contol the pumps.


Easy networking as well

The 17 pump stations in Halmstad are controlled by different industrial networks. To communicate with these, CG’s drives are delivered with an Anybus module from HMS. This pluggable communication module enables CG’s drives and soft starters to communicate with many different networks. Prästjorden’s Water Station, for example, use both Modbus- TCP and PROFIBUS to control the different pumps.  “The communication modules enable us to connect our products to several different networks,” says Lars-Olof Pejner, who is CG Drives & Automation’s account manager for Halmstad Municipality. “The communication modules also make it easier for the system integrators when installing the products in the electrical cabinets.”