Brochure

6
Anity laws are the key
to energy savings
By using AC drives in air handling units, the quality of the air and the indoor
comfort are increased, while obtaining consistent energy savings, and reducing
maintenance cost.
Higher control reduces consumption
The considerable daily load variation in HVAC facilities makes it
economical and attractive to install AC drives on more or less all
rotating equipment such as pumps and fans.
The benets obtained are typically:
• Better air quality and indoor comfort
• Substantial energy savings
• Better asset protection
• Less maintenance cost
• Higher plant reliability/performance
In a system using centrifugal or rotodynamic pumps and blowers with friction loss, major energy
savings can be obtained by using Danfoss AC Drives. A reduction of just 20% in pumping speed
or ow rate, can generate savings of up to 50% in energy consumption.
The level of energy savings is considerable, even with a high content of static pressure. Reducing speed
by 20% can typically generate 20-30% savings in energy consumption within the air handling unit.
The explanation for the high increase in energy eciency within systems that have an AC drive
resides in the Anity Laws. The principle of the law is described in the graphics below.
Nominal
power
Nominal
ow
12.5%
Speed/ow
The Cube Law
The power consumed = Speed
15 kW pump at 80% of rated speed
Power = 15 kW × (0.8 × 0.8 × 0.8)
Power = 7.68 kW (52% nominal)
15 kW pump at 50% of rated speed
Power = 15 kW × (0.5 × 0.5 × 0.5)
Power = 1.87 kW (12.5% nominal)
50%
Energy Used
50% ow