Baldor creates custom firmware for pressure control application

Thrush Co Inc, an industry-leading hydronics company, has developed an energy-saving water pressure booster system that is based on a Baldor VS1MD variable-frequency microdrive and high-efficiency motor. Known as the Pressurizer-VS, the system is provides supplemental pressurisation of water supplies using a preemptive control scheme that employs custom Baldor-developed firmware to regulate output flow and pressure very efficiently and accurately. Typical applications include maintaining proper water pressure on the upper floors of high-rise buildings, and ensuring constant pressure for critical processes such as cooling industrial, medical and laboratory equipment.

All Thrush pressurisers are designed to increase water pressure at the point of need and to accommodate changes in system flow rates in order to ensure correct operation of devices such as flush valves, dishwashers, washing machines and shower heads. For its latest Pressurizer-VS product line, Thrush wanted to set a new performance standard by designing a pump control system with an exceptionally narrow pressure deadband, to eliminate temperature fluctuations in mixing valve applications. The company also sought to minimise the power consumption of the system so as to minimise users' running costs.

The Pressurizer-VS uses a Thrush TV2g in-line pump coupled to a vertically-mounted motor, with an adjacent hydropneumatic pressure tank that enables the system to react instantly when water is demanded and prevents the system cycling during small infrequent demands. The physical layout of the entire system results in a very compact footprint, enabling the unit to be fitted in areas too small for conventional systems. The pressuriser is available with a number of different motor and drive options, covering flow rates up to 200gpm (910 lpm) and pressure boost ranges from 30-80psi. As standard, the system is supplied with a Baldor high-efficiency drip-proof motor, controlled by a Baldor VS1MD microdrive.

Custom firmware

Aaron Schipper, an Applications Engineer at Thrush, comments; "We chose Baldor's VS1MD variable-frequency drives primarily because of their controllability and efficiency; the drives' V/Hz control mode enables us to regulate output pressure very accurately, and their sleep and wake-up functions help minimise energy consumption. In fact, we received excellent applications support from Baldor, who created customised versions of these functions so that they can be invoked directly by pressure transmitter signals. On the Pressurizer-VS, we pre-pressurise the hydropneumatic tank immediately prior to no-flow shutdown so that the system is always ready to respond to demand - a unique feature that we call 'Sleep Boost' - and this has only been possible thanks to Baldor's willingness to create custom firmware. We also make use of the drive's soft-start capabilities, to eliminate any power spikes on start-up."

Thrush introduced the Pressurizer-VS to the market in the summer of 2010 and it is already enjoying considerable sales success. As a result of Baldor's support on this new product line, Thrush has now made the company its 'Supplier of Choice' for all future projects involving variable-frequency drives.

Baldor's V*S microdrives are some of the smallest, most powerful and cost-effective products of their type on the market. The VS1MD model used in this application is a general-purpose drive, available with stock ratings up to 11kW (15HP) and with production ratings up to 22kW (30HP). Its compact size, user-friendly interface and high power output capabilities make it suitable for a wide variety of applications.

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