Product category:
Industrial Drives/Controls
News Release from: Danfoss Motion Controls | Subject: VLT 8000 Aqua
Edited by the Engineeringtalk Editorial
Team on 06 April 2004
Drives designed for pumping duties
A new range of drives is particularly aimed at the water and wastewater industries.
A new range of drives is particularly aimed at the water and wastewater industries Recognising that pumps make specific demands of drive technology, Danfoss has responded to customer demands by launching the VLT 8000 Aqua drive, specifically designed and equipped to meet the needs of the water/wastewater market
Although pumps represent a broadly quadratic load, somewhat similar to fans, they need a wider range of control capability to simplify drive application.
Aqua offers both quadratic and constant torque performance capabilities making it ideal for both centrifugal and constant torque applications.
Based upon the renowned Danfoss VVC+ control strategy, the Aqua series enables the motor to be run at full load/speed without any motor derating requirement.
At the same time, high energy efficiency is achieved by automatic energy optimisation software which actively controls the motor flux in respond to load demand, enhancing motor and drive efficiency and minimising losses.
The new enclosure design of the high-power Aqua models means that they are now more than 35% smaller than previous models, and are the most compact fully featured drives in their class.
Reliability is critical and in many pump applications, drives are frequently installed in remote locations and effectively left to fend for themselves.
The auto-derating feature of the Aqua ensures that even under phase-loss and supply voltage imbalance, the drive will self-protect by reducing the output frequency and hence power, for the duration of the condition.
In the same way, this feature protects the drive against damage from increases in ambient temperature beyond the design point.
Duty/standby operation, a frequent requirement on pumps, is catered for by pump alternation controls which allow the drive to control either of two motors, both of which it is tuned to.
An embedded timer allows the user to select the run-time for the duty pump-set before change-over to the standby is initiated, to even out wear on the system.
"Pipe-fill" mode is incorporated to control the fill-up of water pipe systems at startup, avoiding water hammer and potential damage to seals or the system infrastructure.
This closed loop function allows the setting of a "filled pressure setpoint" and the fill rate can be set as desired.
For multiple-pump applications, the Aqua series offers an inbuilt cascade control option for controlling multiple pump installation whereby a "lead" pump can be variable-speed controlled while up to four fixed-speed "lag" pumps can be staged on/off, eg by Danfoss MCD soft-starts, to achieve efficient ultrawide flow variation across the full capacity of the installation.
Alternating lead pump control ensures that one pump does not experience greater duty than the others on the system.
For master-slave systems with multiple VSDs operating in parallel, free multiple unit staging efficiency calculation software enables the user to enter pump and system data to achieve optimum efficiency for the system as a whole.
Aqua offers ratings up to 400kW and IP54 enclosures rated to 40C as standard, RFI compliance to EN55011-1A with up to 300m of shielded cable, RS485 as standard and optional communication via Profibus, Lonworks, Devicenet and Modbus RTU.
The Aqua range has already been adopted by the DRD Water Services in Northern Ireland and consequently a framework agreement covering the use of the Aqua for a wastewater aeration treatment process has been awarded to Danfoss customer, EPS Environmental, who already has a number of Aquas installed and running.
Brian Atkinson of Drives Solutions Partner, Greenville Electrical, reports: "The Aqua series has proved very popular because, as standard, it so closely matches the needs of the water industry".
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