HVACR technicians have traditionally swapped out customers’ faulty blower motors with like motors, and, more often than not, those motors have been single-speed permanent split capacitor (PSC) units. But, over the years, several manufacturers have developed variable-speed electronically commutated motors (ECMs) specifically designed as retrofit replacements for faulty PSC motors. And, while not all contractors consistently offer ECMs, those who do often report increased profits as well as improved customer comfort and satisfaction. Source: www.achrnews.com/articles/128247-retrofitting-psc-motors-with-ecms Due to high speed rotation of the rotor some wear and tear is caused along with the heat generation due to friction. To minimize this problem, bearings are used to reduce the friction between flange and the rotor. Most PSC motors use Ball Bearings. As the name suggests, a ball bearing is a ring of steel balls which are placed around the rotor. These balls are free to roll and are lubricated using grease (As unlike oil, grease tend to stick to the surface and does not drift away at high speeds). These bearings are held in place around the rotor using a bowler ring attached to the flange. Since the bowler ring is attached to the flange, it does not rotate along with the bearings and remains stationary to keep the bearing balls held in the right place. In order to prevent air leakage from the motor, the bearing ring is kept at a minimum distance from the housing, causing an increased zero flow static pressure as compared to sleeve bearings used in other motors.
Source: gemsmotor.com/ac-fan-blower-psc-motor
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