ABB pump and fan AC drives offer low voltages
Energy Saving Pumps Fans
The new ABB drives are low-voltage for pump and fan applications. ABB has launched a range of low voltage AC drives specifically targeted at pump and fan applications, offering models from 0.37 to 22 kW.
The new ABB AC pump and fan drives are described by the manufacturer as fast to install and commission for pump and fan applications with a powerful set of features which benefit pump and fan applications, along with advanced energy efficient functionality.
Built-in PID controllers are used to vary the drive’s performance in response to changes in pressure, flow or other external data, modifying the performance according to the needs of the application, says ABB. This is designed to eliminate the need for an external PLC and also to help save energy.
The ABB AC drives feature a pump and fan control (PFC) feature which modulates the speed of the main pump or fan and brings any auxiliary pumps or fans on line as necessary. ABB says the drives can even manage switching between pumps or fans to ensure that they are all used to the same extent over the long term.
In addition, the ABB AC drives include soft pump and fan control (SPFC) which further reduces unwanted pressure peaks in pumps and pipelines.
Also among the standard energy efficiency features incorporated into the pump and fan drives is the energy optimiser, designed to help to make adjustments in areas such as noise and efficiency. The drive’s internal fan is controlled by software to reduce losses, further improving energy efficiency.
Energy savings can be easily monitored using the built-in energy counter, which displays energy savings in kWh, or local currencies, says ABB.
The Pump and Fan Curve
A centrifugal pump or fan running at half speed consumes only one-eighth of the energy compared to one running at full speed. This is because the torque needed to run a pump or fan is the square of the volume. For instance, reducing the pump speed to 80% only requires 64% of the torque (0.8×0.8) (Tµn2).
Energy Saving Pumps Fans
Furthermore, to produce 64% of the torque only requires 51% of the power (0.64×0.8) (Pµn3), as the power requirement is reduced in the same way.
The explanation for this lies in the pressure difference across the impeller. When less pressure is produced, less acceleration of air or fluid across the impeller is required. It is the simultaneous reduction of acceleration and pressure that multiplies the savings.
Even further improved energy efficiency is offered through a technique called motor flux optimisation. This is particularly beneficial in pump and fan applications and under light loading conditions. The overall efficiency of an ABB low voltage AC drive and its motor is typically 1% to 10% higher than conventional AC drives. At 25% load, efficiency is up to 10% better.