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Motor brutal stop

Old 04-15-2018, 06:49 PM
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xalm04
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Default Motor brutal stop

Hi, today I was flying my P-19 and on the 3/4 roll stall turn the motor began to make some funny sound, and at the top just stopped like something was broken. I managed to land it safely, and I thought the problem should be a total destruction of the contra drive, or the motor. However after disassembling and checking it, all seems to be OK, but I found one of the 3 leads from the ESC to the motor disconnected. At the field I though it was caused by the stop, as the motor mount was loose because of how hard the stop was, but now I think maybe this was the cause. Someone has experienced a hard stop for disconnecting one of the 3 connectors?
Old 04-15-2018, 07:25 PM
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Jason Arnold
 
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It sounds like your ESC died. The solder on the motor wire probably got so hot it melted.

I'd be giving the motor windings a good inspection before trying again. It may be a motor failure that led to the ESC frying.

Cheers,
Jason.
Old 04-16-2018, 03:12 AM
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preston blake
 
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I agree with Jason. My understanding of motor/ESC electronics is incomplete but loss of commutation can lead to multiple types of failure in the motor or ESC. One can have a bad solder joint at the motor,bad solder joints at the connectors or bad solder joints at the ESC. Once one of those three wires has increased resistance compared to the others, the ESC and motor cant talk to each other accurately and some type of failure is imminent. I'd enjoy if a more knowledgeable person would expound on this further.
I would also check the pinion gear in the contra unit. I've had two strip on V3 units, one after a prop strike, another when my Neu siezed...none so far on my V4. If the pinion gear strips in flight the props stop or free spin and your aircraft's glide ratio assumes that of a brick.
Old 04-16-2018, 03:30 AM
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bem
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Hi,
In summer 2016 I had a motor stop in the air, Hacker Q80-14XS motor and Hacker/Jeti MasterMezon 90 with BEC in use. When I had glided down to a landing and opened the canopy It was burnt smell. When I took out the ESC I could smell burnt at the end where the capacitators are placed. No cables melted, no black sot, just the burnt smell. Terrible noice (like a stone-breaker) from motor when testing to apply a little throttle so the ESC could not give commands to motor correctly.

I replaced with a new same ESC but I still used same Hacker Q80-14SX (so I did not change that) as before and it has worked fine since that (many hundred flights).

/Bo
Old 04-16-2018, 05:34 AM
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nonstoprc
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I once had a similar incident in which one wire disconnected from the ESC to the Neu motor at the connectors. The plane experienced a dramatically slow down in the air but the prop kept spinning. After landing, I checked the ESC (Jeti Spin 99) and found there was a commutation error.

Once the wire was reconnected, the motor just run fine.

Last edited by nonstoprc; 04-16-2018 at 05:39 AM.
Old 04-16-2018, 05:47 AM
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kenh3497
 
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I'm not much of an electric guy but I know for a fact a three phase motor will not start on two phases but will run on two phases. Two phase power is very limited. This knowledge comes from working with machine tools in an industrial setting. I would also guess that an ESC with one phase disconnected will be in for trouble.

Ken
Old 04-17-2018, 04:57 AM
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I connect my Jeti ESC to motor via 4mm bullet plugs / sockets. In the air I've had these pull apart once or twice, resulting in only two of the three motor leads being connected. This happened during a schedule resulting in the motor stopping as the ESC blew (without any smoke). It completely wrecked the ESC but the motor was unharmed. Fitted a new ESC and all was well again

Keith
Old 04-17-2018, 05:28 AM
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A piece of shrink tubing over the ESC - motor bullets will ensure they don't pull apart.
Old 04-17-2018, 05:59 AM
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Yep, that's what I did and its worked okay since!
Old 04-19-2018, 02:30 PM
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If the motor looses one of the three wires it will get out of sync as it work under a rotating magnetic field, also the two remaining wires will have an increase in Amps, so besides the noise the amps differential might make the ESC to shut off for safety (this is not on all ESC's so not really sure).

All the other options or cases are equally valid, this is just one more.

Regards

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