Is it cost effective replacing functioning VSDs?

ABB UK ACH550 inverter drive for HVAC

How cost effective is replacing functioning VSDs?


ABB advises replacing functioning VSDs, even if they have not failed, depending on the circumstances. But then, they would say that wouldn’t they, as they get to sell another drive. Their arguments are sound, and suggest an old drive could be costing money unnecessarily, compared to more modern and efficient products.

Replacing functioning VSDs

Today’s drives are at least 3% more efficient than their predecessors. For example, a new ABB 75 kW drive would consume 6,704,082 kWh of energy, costing £301,684, over ten years. In contract, an older SAMI STAR 75 kW drive would consume 6,915,789 kWh, and £311,211, over the same period. This is a saving of almost £1,000 per year.
Typically, VSDs have a ten to fifteen-year operating life, and replacing a drive before it fails can reduce expensive downtime costs. They also point out that replacing old drives brings several benefits to the HVAC. These include increased energy efficiency, reduced running costs, and using less floor space. They even help with disposal of your old variable speed drives.


Moreover, new drives are simpler to connected to a BMS control. They also have Ethernet onboard, aiding remote operation and monitoring. They also offer improved fault-finding and load monitoring functions to detect failures in associated equipment. Finally, they have far better harmonic mitigation.


Variable speed drives not only decrease energy use as well as lessen the burden on the environment, they also qualify for the Government’s Enhanced Capital Allowance scheme. This grants 100% capital write-off in the first year. It is not unusual for user to dismiss the promise of 50% energy saving on a 20% speed reduction as the exaggerated claims of a manufacturer.


To verify savings from replacing functioning VSDs, ABB suggests starting with an energy survey enabling users to make informed decisions that benefit company profitability.


Go here for more ABB energy saving VSDs

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