- reduce the speed of a single phase induction motor - 4 Updates
- Old 'Scope inductor and cap help please - 1 Update
| fynnashba@gmail.com: Oct 07 04:04PM -0700 Hi Comrades, please what is the simplest way to reduce the speed of a single phase induction motor to about 50%? also can a universal motor run for 24 hours on 90% load? (with all name plate ratings observed) thank you. |
| Phil Allison <pallison49@gmail.com>: Oct 07 05:51PM -0700 fynn...@gmail.com wrote: ---------------------------- > Hi Comrades, please what is the simplest way to reduce the speed > of a single phase induction motor to about 50%? ** Just feed it with 25 or 30 Hz sine wave at about half voltage. Or if that is a problem, use a gear or belt reduction system. > also can a universal motor run for 24 hours on 90% load? ** 24hrs, no problem. But after that it is totally buggered. .... Phil |
| "pfjw@aol.com" <peterwieck33@gmail.com>: Oct 08 04:05AM -0700 > Hi Comrades, please what is the simplest way to reduce the speed of a single phase induction motor to about 50%? > also can a universal motor run for 24 hours on 90% load? (with all name plate ratings observed) > thank you. What we would need is horsepower, operating voltage, then anticipated maximum load. https://cdn.automationdirect.com/images/products/large/l_gs110p5.jpg These exist, but as the load increases, so does the cost. As to operational capacities, if the motor is rated as "continuous" and properly cooled, there should be no issue about how long it runs as long as it is within its design load. NOTE: "Design Load" is generally some amount less than "Maximum Load". But not too much, typically around 10% - so you need to know which "90%" you are measuring. https://www.plantengineering.com/articles/keeping-it-simple-steps-to-determine-motors-actual-load/ Gives you more on the subject. Peter Wieck Melrose Park, PA |
| etpm@whidbey.com: Oct 08 09:17AM -0700 >Hi Comrades, please what is the simplest way to reduce the speed of a single phase induction motor to about 50%? >also can a universal motor run for 24 hours on 90% load? (with all name plate ratings observed) >thank you. It depends on what type of single phase induction motor. The typical single phase motor that you see powering bench grinders and the like will often have a centrifugal starting switch, a potential relay, or an electronic switch that controls the starting winding. These cannot be made to run at 1/2 speed without extensive modification and a power supply that provides AC at 1/2 the frequency the motor is rated for. Other common motor types may not have any type of switch and instead use a capacitor permanently connected to one winding to shift the phase. These motors would also need the 1/2 frequency. The reason for the 1/2 frequency is that the speed of most induction motors depends on frequency. If the voltage is lowered the motor will start to slow and will then consume more current in an effort to speed back up to normal operating speed. If the voltage gets too low the motor will just stall and then will overheat and eventually burn up if the power supply can deliver enough current. This stalling will happen way before the motor drops to 1/2 speed. Shaded pole induction motors are controllable to some extent by lowering the voltage. These motors are not very efficient. They are mostly used for applications requiring little torque, like the turntable in a microwave oven. Shaded pole motors are sometimes used for fans and controls for these can be bought at any store that sells home improvement stuff. Shaded pole motors have a tiny starting torque and so are not practical for anything other than starting very light loads, such as fans and turntables. Their speed regulation is also poor as it is quite sensitive to load changes. Unfortunately there is no simple way to lower by 1/2 the speed of a typical single phase induction motor. Eric |
| Fox's Mercantile <jdangus@att.net>: Oct 07 12:03PM -0500 > electrolytics there are some others that, from what I've read about > and seen on YouTube, are also suspect. > Eric Caps are cheap. Collateral damages from bad caps are not cheap. Replace ALL the electrolytics. Replace ALL the paper caps. Leave the silver dipped micas, tubular ceramics, and any "postage stamp" micas alone for the time being. Replace them one at a time. Take pictures, make notes. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
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