ACH550 energy saving drives for chilled water pumps



ACH550 energy saving drives for chilled water pumps


Fan and pump applications continue to offer opportunities for saving money through energy saving.  Although in most new installations equipment is optimised for energy saving, there is a huge installed base of fan and pump motors that spend their life either turned off or running at full speed. A typical example is with chilled water pumps.


In most of these applications the motor will have been over-sized for the load (wasting more money) and flow is controlled by valves or dampers.  By controlling the motor speed with a variable speed drive, the speed can be infinitely controlled to suit the application, and energy savings of 30-50% are regularly achieved.


Drive manufacturers like ABB UK produce ranges of variable speed drive (VSDs) specifically for building services application, like the ACH550 used for energy saving for chilled water pumps.


Chilled water pumps

Chilled water pumps are used to move cold water from the chiller to the air handling units. The chilled water is used to cool and dehumidify air within a building.  Hot water pumps simultaneously move hot water and heated air within the building.


Pumps are used for raising, transferring, or compressing fluids, and represent the largest single use of power in industry (31 percent) by motor driven equipment. Most of the time pressure within a system and the flow of gases and liquids are regulated using mechanical clutches, throttles and adjustable inlet guide vanes, however controlling an application this way is inefficient, requires frequent maintenance and provides inaccurate control.


Pumps have two main categories:

  1.  Positive displacement pumps force a fixed volume of fluid from inlet to discharge with each stroke or rotation. (e.g., reciprocating, rotary, or screw type pumps)
  2.  Centrifugal pumps which use the fluid’s own momentum to build up pressure or head. Centrifugal pumps use centrifugal and hydrodynamic forces to create pressure that moves the fluid from inlet to discharge.


An ACH550 can be used to control the impeller speed, in order to modify the pump curve. The benefits are cost and performance related. Drives reduce peak energy demands by capturing the speed of a pump that is running backwards due to back pressure. Built-in start function causes a free-wheeling pump to reverse and restart under controlled conditions unlike a line started pump motor.


In addition to reducing energy costs by lowering motor speeds, ACH550 VSDs lower peak energy demands.  Other benefits include improved temperature balance am reduced noise levels.  Maintenance requirements are reduced and component life increased.


ACH550 and other ABB VSDs available her at discounted prices

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