VACON® 100 FLOW improves water pumping in Kristinestad

KRS-Vesi is responsible for water supply in the Kristinestad area on the west coast of Finland. Controlling the pumps – the workhorse in the water supply – with VACON® 100 FLOW AC drives results in an even flow and reduces pressure spikes in the pipes. The VACON® 100 FLOW is dedicated to improving flow control in pump applications.

VACON® 100 FLOW combines the core design of VACON® 100 with dedicated functions that benefit flow control processes. The new AC drive also improves the efficiency and redundancy of pump systems, offering advanced features such as Multimaster and Multifollower for controlling multiple pumps simultaneously.

When KRS-Vesi saw that modernization was necessary at their Friiveli booster station and Osvald waste water pumping station, their pump supplier Grundfos included seven VACON® 100 FLOW AC drives in the power range 5-15 kW in its offer. Three of the VACON® 100 FLOW units are installed at the Friiveli booster station and four units are at the Osvald waste water pumping station.

Each pump is controlled by an AC drive – smoothly
Before modernization, a conventional pump solution was used at the Friiveli booster station: the main pump was controlled by an AC drive, and a separate contactor unit was required to switch on two auxiliary pumps. After modernization, each of the three pumps is controlled by its own VACON® 100 FLOW drive, and a separate contactor unit is no longer needed. At the Osvald waste water pumping station, direct on-line starting was previously used to start the pumps. This caused a pressure spike in the pipes and mechanical stress on the equipment. After modernization, the VACON® 100 FLOW units accelerate the pump motors quickly but smoothly to their running speed, avoiding extra mechanical stress on the parts.

The VACON® 100 FLOW drives provide multipump functions as standard, which improves reliability and efficiency. The drives in a system communicate with each other via a Modbus RTU communications protocol. They are able to judge how many pumps are needed at any particular time and at what speed the pumps should operate, and notice if there is a fault in one of the motors, pumps or AC drives. If the demand exceeds the maximum capacity of the leading pump and more capacity is needed, auxiliary pumps are connected as needed. The leading pump and the auxiliary pumps run in parallel, which saves energy and reduces wear on the pumps.

“The Multipump Multidrive system improves redundancy. Starting the pumps smoothly decreases the stress on the electrical network and mechanical parts and reduces pressure spikes in the pipeline,” says Kimmo Äijö, Service Technician at Grundfos Pumps.

Commissioning the VACON® 100 FLOW is easy and quick and does not require any special skills. “Multipump Multidrive is a modern solution whereas an AC drive-contactor-combination is yesterday’s technology. We have found the AC drive application to be very good and recommend it to our pump customers,” says Kimmo Äijö, who has been working together with Vacon for more than 10 years.

Even flow and pressure
Pump control with the help of AC drives also brings other benefits, such as improved process control and optimum pump control. According to Grundfos’ Kimmo Äijö, the most important benefits of the VACON® 100 FLOW units at KRS-Vesi are a steady flow and pressure. “Thanks to the process control enabled by the VACON® 100 FLOW AC drives, the flow rate from the Osvald wastewater pumping station to the wastewater treatment plant is steady. At the Friiveli booster station the VACON® 100 FLOW drives keep the pressure stable.”

Energy and space savings
Energy savings are one of the most important benefits that AC drives bring. Process control with the help of AC drives can reduce energy consumption by 20-50%. The greatest savings are seen in pump and fan applications, when the speed of the motor is constantly adjusted according to process requirements. The power required by the drive is proportional to the third power of the speed. This means that even a small drop in speed leads to huge energy savings.
AC drives technology also reduces the need for space and cabling. All VACON® 100 FLOW drives delivered to KRS-Vesi were provided in splash-proof IP54 enclosures, which can be installed on the wall in the close vicinity of the process. This brings space savings in cramped electrical rooms and reduces the need for cabling.

The VACON® 100 FLOW drives have been controlling pumps at KRS-Vesi since May-June 2013. “We are very satisfied with the solution,” says Ari Hakala, Maintenance Manager at KRS-Vesi.

KRS-Vesi was familiar with VACON® AC drives technology even before the VACON® 100 FLOW units were installed. The VACON® CX and VACON® NXS range of drives have been used for years at their water treatment plant and other water intake plants.

Please note that Vacon joined the Danfoss Group in December 2014.