AC Motor FAQs

What is an AC motor?
Historically DC motors were the way to control the speed of your process giving accurate speed and dynamic responses to load demands. The humble AC motor was generally a fixed speed device with clever gearboxes and interfaces to do speed control. The invention of inverters changed this over time and now AC motors have performance equivalent of their DC counterparts without their problems. With AC there is no need for complicated brush gear and associated regular maintenance costs.

What is the life expectancy of an AC motor?
There are many factors that affect the life expectancy of an AC induction motor (or any electric motor). These factors can include input power problems, improper mechanical installations, malfunctions in the load, environmental factors, among others. Assuming that the motor is being operated under normal conditions, sized correctly for the application and within the manufacturer’s design requirements, it can last 15 years or more.



Should I rewind an AC motor?
Rewinding a motor is usually the result of a catastrophic failure in the motor’s insulation and windings and is usually due to a thermal breakdown. Hence, generally speaking, a motor that requires rewinding may not have been operated under normal conditions. Motors are frequently replaced rather than rewound due to costs, convenience and the claim that rewinding may reduce the motor’s efficiency.

Why would the motor bearings fail?
Early failure of motor bearings is usually the result of improper mechanical installation causing undesirable forces acting on the bearings, or simply poor maintenance. Bearings should be inspected regularly for lubrication and uncharacteristic noises. Their life expectancy depends on factors previously cited.

Why not fit an ABB smart sensor to monitor your motor giving regular indications on the performance and condition of your motor? Contact APDS for more details.

Should I use a DC or AC motor on my application?
The arrival of European Minimum Energy Performance Standard (EUMEPS ) has users reviewing their applications and the new regulations means that only the most efficient motors are now used on new processes. AC motors are more efficient that DC motors and so we always recommend this option.

If you have a significant number of old motors that are running at low efficiency, we recommended carrying out a site survey. We can help you with this and also identify the potential energy savings.

APDS are your motor experts. Contact us today to discuss a motor management policy and
how to save your company energy and reduce  down time.