WEM AC VARIABLE SPEED DRIVES HOW DO THEY SAVE ENERGY & OTHER BENEFITS

The VSD represents technology that boosts the performance of an electric motor and saves energy. VSD's enable more cost effective production, reduce the greenhouse effect, a play a part in meeting emissions targets. Despite this, less than 1 in 10 electric motors in the world is fitted with a VSD - financially it would be justified to install a VSD on at least 1 in 3 electric motors

Typical Applications for Industrial Plants:

•FD, ID, Primary & Secondary Air Fans

•Boiler Feed, Chilled Water, River Water Pumps

•Compressors

Typical HVAC Applications:

•AHU Fans (VAV & CAV Systems)

•Supply & Extract Fans

•Heating & CW Pumps, Duty/Standby Pump Sets

•Compressors & Chillers

Typical Applications for Leisure and Commercial Buildings:

•Swimming Pool Pumps & Ventilation

•Sports Halls, Gymnasiums & Dance Studios

•Fountains

•Ice Rinks

Some facts…

•Electric motors consume 64% of all non-domestic energy consumption

•Total population of electric motors >10 million

•3000 motors purchased everyday – most used on fans, pumps and compressors

•Rmillions could be saved through careful management

How does a VSD save energy?

A VSD regulates the speed of the motor, and in turn the speed of the pump or fan, by controlling the energy that goes into the motor, rather than restricting the flow of a process running constantly at full speed. Running a motor at full speed while throttling the output is like driving a car with one foot on the accelerator and the other on the brake; a part of the produced output immediately goes to waste. A VSD can save over 60% of the energy as it controls the energy at source, only using as much as is necessary to run the motor with the required speed and torque - much in the same way as the accelerator in the car controls the engine revs.

In particular, VSD’s can dramatically reduce energy consumption in fan and pump systems. The power required to run a centrifugal pump or a fan is proportional to the cube of the speed. This means that if 100% flow requires full power, 75% requires 0.753= 42% of full power, and 50% flow requires 0.53= 12.5% of the power. As a small reduction of the speed can make a big difference on the energy consumption, and as many fan and pump systems run at less than full capacity a lot of the time, a VSD can make huge savings compared to a motor driving an load under mechanical control.

A VSD can also make it possible to stop a motor completely when it is not required as re-starting with a VSD causes far less stress than starting direct-on-line - soft starting is an inherent feature of the VSD. Regulating the motor speed has the added benefit of easily accommodating capacity rises without extra investment, as speed increases of 5-20% is no problem with a VSD as long as there is enough spare capacity in the system.

Other advantages of Variable Speed Drive Control …

•Lower starting current

•Reduced mechanical stress

•Flexibility of operation

•Reduced noise levels

•Reduced hardware requirements – starters, power factor correction, metering/monitoring, PI control, etc. no longer required