Perminant Magnet Motors  - Page 1
Forum section: electronics / beginners

author: electromateria
author_rank: Regular Contributor
timestamp: May 19, 2022, 03:50:39 am
content: I need some medium or large sized motors with magnets to mess around with, where's the best source to salvage them?From my findings:Electric lawnmowersTreadmillsIs there any other source that's even more common?

author: IanB
author_rank: Super Contributor
timestamp: May 19, 2022, 04:12:07 am
content: Quote from: electromateria on May 19, 2022, 03:50:39 amBattery operated power tools: electric drills, etc.

author: IanB
author_rank: Super Contributor
timestamp: May 19, 2022, 04:13:19 am
content: Also cars: windshield wipers, electric windows.

author: tepalia02
author_rank: Regular Contributor
timestamp: May 19, 2022, 07:22:43 am
content: Blender for medium-sized motor.

author: CaptDon
author_rank: Super Contributor
timestamp: May 19, 2022, 08:20:11 pm
content: There is a source if you can find them, Magnetron tubes in the .5 to 1MW class. The military used to scrap them out on pallets, some were electrically toasted and not rebuildable, and some were even brand new never used. Most of the big tubes had two magnets each at nearly twenty pounds and were capable of lifting outboard motors out of the water even though most of an outboard is aluminum!! If you ever got the two magnets stuck to each other it was nearly impossible to separate them without winches or tools!!

author: Ground_Loop
author_rank: Frequent Contributor
timestamp: May 19, 2022, 10:19:38 pm
content: Residential HVAC blower motors less than 15 years old.

author: BeBuLamar
author_rank: Super Contributor
timestamp: May 19, 2022, 10:30:28 pm
content: Quote from: Ground_Loop on May 19, 2022, 10:19:38 pmI don't think they have permanent magnet. AC motors rarely have permanent magnet although some do but not normally.

author: CaptDon
author_rank: Super Contributor
timestamp: May 19, 2022, 10:57:58 pm
content: Bebu, I'm with you. Some of the motors suggested by other posters are either Shaded Pole Squirrel Cage or series wound armature/stator and neither type have any permanent magnets.

author: james_s
author_rank: Super Contributor
timestamp: May 19, 2022, 11:06:46 pm
content: Quote from: BeBuLamar on May 19, 2022, 10:30:28 pmThey almost all do now, the HVAC industry calls them "ECM" motors which is just another name for permanent magnent BLDC. They are effectively required now to comply with efficiency mandates. I installed three furnaces last year and all of them had ECM blowers. I took one of the motors apart because it had a bit of debris in it that was making a noise and confirmed that it is indeed a 3 phase motor with a permanent magnet rotor.

author: Ground_Loop
author_rank: Frequent Contributor
timestamp: May 19, 2022, 11:16:54 pm
content: Quote from: BeBuLamar on May 19, 2022, 10:30:28 pmYep, they are, almost universally now. They have an electronics drive package attached to the motor base to communicate with the blower controller and generate the PWM. Won't meet SEER ratings without them.

author: james_s
author_rank: Super Contributor
timestamp: May 20, 2022, 12:14:20 am
content: They make a big difference too, continuous fan circulation is actually practical now. I checked the draw on my brother's furnace when I installed that and on low speed fan it only draws about 10 watts and this is a 3/4HP motor at full speed. Compare that to more like 80-100W for a PSC motor running on low.

author: electromateria
author_rank: Regular Contributor
timestamp: May 20, 2022, 12:19:02 am
content: Quote from: tepalia02 on May 19, 2022, 07:22:43 amFrom the ones I've seen blender / food processor motors are induction, not permanent magnet unfortunately.Quote from: CaptDon on May 19, 2022, 08:20:11 pmWow! Would love to get my hands on some of those huge magnets. Not even sure what I'd do with them - and it's definitely a safety risk to have magnets that size.. but I would love to get some. Do you have any tips on buying discarded military electronics?I'm really looking for some curved magnets to build custom motors.Quote from: james_s on May 19, 2022, 11:06:46 pmInteresting. I just took apart 5 or 6 HVAC blowers but they were the old style (20-30 years old) with crappy induction motors. I did get some nice bushings and shafts but the motors were junk, I'll keep an eye out for some newer ones

author: IanB
author_rank: Super Contributor
timestamp: May 20, 2022, 01:11:39 am
content: Quote from: electromateria on May 20, 2022, 12:19:02 amWhy were the motors junk? Induction motors usually last forever unless their windings burn out or their bearings seize up.

author: David Hess
author_rank: Super Contributor
timestamp: May 20, 2022, 01:43:00 am
content: The voice coil actuator in a hard drive has a pair of very strong magnets which are not too difficult to remove.

author: james_s
author_rank: Super Contributor
timestamp: May 20, 2022, 01:44:44 am
content: Quote from: electromateria on May 20, 2022, 12:19:02 amThey're not induction, they're series wound universal motors that you find in blenders and line powered power tools.Why do you keep taking stuff apart? I remember now, you're the guy who keeps turning useful stuff into scrap. What on earth are you going to do with bushings and shafts from blower motors? I'm not suggesting these were particularly high value items or anything to begin with but disassembled they are scrap value. You seem obsessed with tearing stuff apart into completely useless bits.

author: IanB
author_rank: Super Contributor
timestamp: May 20, 2022, 02:49:50 am
content: Quote from: james_s on May 20, 2022, 01:44:44 amThat doesn't seem right. In my furnace, and in every online reference I have seen, they are induction motors with start/run capacitors.

author: electromateria
author_rank: Regular Contributor
timestamp: May 20, 2022, 03:01:16 am
content: Quote from: IanB on May 20, 2022, 01:11:39 amThey were 20+ years old and didn't run when I wired them up, I didn't bother opening them to check why I just sent them to scrap. It appeared all the insides were coated in nasty sticky dust but can't say for sure that's why they seized. They were really crusty, not worth investing time into. One of them started smoking when I tried to start itQuote from: james_s on May 20, 2022, 01:44:44 amAre you sure? I took apart a few and didn't see any magnets, watched some yt teardowns too and couldn't see magnets.https://en.wikipedia.org/wiki/Universal_motor^ says it uses electromagnet, I don't understand.. electromagnet isn't the same as a permanent magnetWhy do I keep taking stuff apart? Ahh that age old questionsounds like something my mom would ask hehe"you're the guy who keeps turning useful stuff into scrap"lmaoBushings and shafts are useless to you, but very useful to me. I'm building out a metal shop for custom fabrication. I have benders, cutters, hundreds of pounds of stock steel, 100 ton hydraulic press under construction, plasma cutter, mig welder, stick welder, custom propane forge, lots of AC / DC motors, etc etc. If I want to build something, bushings and shafts are very useful. A 40 year old blower caked in filthy dust won't sell on kijiji for $20 (tried before disassembly / scrap).

author: james_s
author_rank: Super Contributor
timestamp: May 20, 2022, 03:05:52 am
content: Quote from: IanB on May 20, 2022, 02:49:50 amHow old is your furnace? ECM motors only became standard within the last few years or so. Have a look athttps://hvacdirect.com/for example and look at how many of the furnaces list ECM motors. They're used for the condenser fans in higher SEER AC/HP systems too.

author: IanB
author_rank: Super Contributor
timestamp: May 20, 2022, 03:12:47 am
content: Quote from: james_s on May 20, 2022, 03:05:52 amIt's very old, probably 30 years or more. The blower certainly does not have an ECM motor, it is a garden variety induction motor. I know this because I recently had to replace the capacitor after it wouldn't start properly.I can't imagine universal motors being installed in furnace blower applications. They would run too fast, they would be too loud, and the brushes would wear out.

author: james_s
author_rank: Super Contributor
timestamp: May 20, 2022, 03:26:45 am
content: Quote from: IanB on May 20, 2022, 03:12:47 amWell a 30 year old furnace certainly isn't going to have an ECM motor, I don't think they appeared on the market until maybe 10 years ago and at that time it was only the high end variable speed high efficiency furnaces that had them.I don't think anybody has suggested a universal motor in a furnace, those are used in the small kitchen appliances that were mentioned. Blenders, mixers, food processors, etc.

author: IanB
author_rank: Super Contributor
timestamp: May 20, 2022, 03:35:20 am
content: Quote from: james_s on May 20, 2022, 03:26:45 amSorry, I guess that was a misreading of your post. Your comment followed the last line, so I took it as a continuation:Quote from: james_s on May 20, 2022, 01:44:44 am

author: james_s
author_rank: Super Contributor
timestamp: May 20, 2022, 03:39:41 am
content: I was too lazy to sort out the separate quotes and just replied to one big block.

author: David Hess
author_rank: Super Contributor
timestamp: May 20, 2022, 09:07:47 am
content: Compared to induction motors, universal motors have the virtue of delivering higher power in a smaller package, and they have higher starting torque making them more resistant to stalling.Less expensive controllers and power electronics have made ECMs economical, but I am not impressed by their reliability. I am getting tired of replacing the evaporator ECM in my refrigerator.

author: BeBuLamar
author_rank: Super Contributor
timestamp: May 20, 2022, 04:01:57 pm
content: My HVAC system, furnace, AC etc.. have no ECM motors. All are single phase induction motors and none have magnet. They are more than 15 years old and less than 20 years old. In my factory I have a lot of motors and the only motors that have magnets are servo motors. I know because I am responsible for all those motors.