April 10, 20179 yr Hi, I have an Unisaw and I bought it second hand about 10 years ago. Up until a few days ago it was opperation fine. But after ripping a few boards, when turing the saw on, the blade rotated slowly and then the 20 Amp breaker tripped. I attempted this a few more times and the same thing happened. I have a planer on the same circut and it worked fine. I took out the capacitor and the other fuse and had them tested at a motor shop and they told me that they were fine. I will attempt to switch the breaker on that line with another, but with this information, what else should I look a that would cause it to draw more amps than normaol on start up? The brushes? Also when I took the capacitor out, it was chuck full of saw dust and I had to take a tool to get the sawdust cleard out to see the connectors on the capacitor. Do you think this may have been an issue, sawdust on the points? Best regards, Ron Edited November 22, 20178 yr by Ron Dudelston tags added
April 10, 20179 yr That's an induction motor, no brushes. When mine did exactly what you described, it was a capacitor (there were 2 on my saw). I suppose it's possible that the sawdust could have caused the problem, did you put the capacitor back and try it? Those cap covers are fairly well sealed (at least mine were), if it works after the cleaning you may want to consider sealing those covers somehow.
April 10, 20179 yr I don't know if this motor has starter contacts. If it does and there is dirt in them. it might cause this to happen.
April 10, 20179 yr can you post some motor specifications - voltage, HP, mag start, Duty cycle, internal overload protection??? Edited April 11, 20179 yr by Stick486
April 11, 20179 yr some things to consider... bearing(s) seizing/dragging/dry... motor/ and/or arbor.... start/run switch... dirty commutator.. open field/armature...... motor misalignment... open leg L2 or L2 .... motor trying to run on 120VAC... damaged power cord or cord cap causing live a short... loose cord cap... ground cross over.. poor/loose/dirty electrical connections... all-about-electric-motors-fa.pdf CAPACITOR TESTING.pdf Electric Motor Troubleshooting (Polyphase).pdf How to check the Windings of a 3-Phase AC motor.pdf meter motor testing.PDF motor troubleshooting.pdf Multitesters and Multimeters 101.pdf TESTING armature windings.pdf Testing Motor Capacitors.pdf Edited April 11, 20179 yr by Stick486
April 11, 20179 yr Author Thank for all that answered. I put the capacitor and other fuse in the saw and it again spun at low speed then tripped the breaker. I have the information on the motor and is listed below. It just started having this problem. Hopefully this information can help some stear me toward finding out what the heck is going on. Thank for the list and PDFs Stick. I will print them out and see if one works. 83-651 YM145TBFR5503AR P HP 3 / RPM 3475 Volts 230 / Amps 12.4 HZ 60 / PH 1 ENC-TEFC Service factor 1 / Frame 145TY-95 Insul Class F / Max Ambient 40 C Time rating CONT / TYPE BFR Design letter L / KVA code letter H
April 11, 20179 yr 1 hour ago, rlpeterson said: I will print them out and see if one works. HP 3 / RPM 3475 Volts 230 / Amps 12.4 HZ 60 / PH 1 ENC-TEFC nice thing is you can do most of the testing w/o pulling the motor... normally a 3HP pulls closer to 15 amps @220 volts... what is your real time voltage at the motor??? measure this as close to the motor as you safely can.. at the switch or contacter (if you have one) is fine... any extension cords or long wiring runs... if you do have have them you can create voltage drops and over time degrades the motor internally and a compromised motor always wants more...... see the loop??? lower voltages result in higher than normal start up/run amp draws... even by 5 volts let alone 10 or 15... 12GA wire in short run would be the rock bottom wire size to have... 10GA would be super... any 14GA in the system is just not a good thing... TEFC - (Totally Enclosed Fan Cooled) may be impacted w/ saw dust... that's a tear apart to correctly fix... seal those cap covers... suspect your breaker.. move it to the top of the list.. doe your saw have magnetic start and who made the motor??? Edited April 11, 20179 yr by Stick486
April 11, 20179 yr My motor was a Marathon, so was a little different. But if all else fails you can pull it and take it to a motor repair shop. Pulling it is not the easiest thing. It's very heavy and getting it out of the cabinet is the hardest part. But the bench test cost me $50, the repair was another $30. BTW, the suggestion to check the starter was a good one....the screws connecting the wires on mine were loose and tightening them up solved a similar (but separate) problem I had. Edited April 11, 20179 yr by Fred W. Hargis Jr
April 11, 20179 yr 6 hours ago, Fred W. Hargis Jr said: Pulling it is not the easiest thing. It's very heavy and getting it out of the cabinet is the hardest part. pull the bolts holding the table to the base and raise it using a motor hoist... (the table).. use nylon liftimg slings and not chains... slide the base out of the way... set the top on tall saw horses... pull up a stool and have at it... talk about 1st rate access and being able to pull full service, maintenance and cleaning ... Edited April 11, 20179 yr by Stick486
April 13, 20179 yr On 4/10/2017 at 3:42 PM, rlpeterson said: I have a planer on the same circut and it worked fine. Ron, you noted you have a planer on the same circuit...Do you plug it in to the same receptacle as the saw or do they have their own dedicated receptacles? Assuming separate, is it possible to plug the planer into the saw receptacle or vice-versa and see what happens? If you have a Volt meter, set on 250 V-AC (or higher) scale and insert leads into the two "hot" legs of the receptacle to verify you have 220-230 Volts. It almost sounds to me like you only have one leg (110V) of your 220V circuit supplying voltage. It could be a bad receptacle, poor connection on one leg of that receptacle or if the wiring run feeds off the planer circuit or at a junction box a bad connection there. I had a similar issue with an electric dryer...once I disassembled the receptacle, the problem was obvious.
April 18, 20179 yr Author I've been busy at work and didn't have much time. I've got the saw plugged into a 12 foot extension cord of number 10 wire plugged into a box on the ceiling next to the dust collection drop to the saw. I took that cord to my planer and it powered right up. I then switched the 20 amp breaker and that didn't help the unisaw but again the planet started. So it isn't a wiring problem, but is internal to the motor. I will have some time tomorrow to take a closer look and will keep you all updated.
April 18, 20179 yr Author Ok, had about an hour to go to my shop before heading to work. I was able to get the motor out of the saw. It is a Marathon motor, I guess I should have seen the "made by...." on the label on the motor. That being said, I think that Fred said that he had the same motor and took it to a shop and for less than $100 got it fixed. Fred, do you know what the problem was in your motor that you had fixed?
April 19, 20179 yr On mine it was the run capacitor. Had I known that I could have fixed it myself, but this way they gave it a clean bill of health. It was about $60 ( I think) for the bench fee and capacitor.
April 19, 20179 yr You said you put the capacitor and fuse back in. Does your motor have 2 capacitors in it ? Were both checked ? Roly
April 25, 20179 yr Author Popular Post Hi everyone, I took the motor apart and when I opened it, it didn't look like any of the videos on YouTube. So I bit the bullet and took it to a shop to be looked over. I got it back today and he said that all he did was clean the motor and the switch. So I guess between me and the previous owner of the saw, used it so much that a lot of dust collected in the motor. So just like a spring cleaning, that what was causing my problem. Total charge to fix it was $50 with the tax. So that could be a reason for anyone else with this problem. But I have to tell you, when I opened the motor, I really didn't see any dust, so it must be microscopic dust that caused the problem. Now back to building a gliding rocking chair for my daughter in law who is giving me my first grandson in the fall. Best to all, Ron
April 25, 20179 yr Glad you good it fixed! And CONGRATS on the new Grandson!! Edited April 25, 20179 yr by Chips N Dust
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.