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Discussion Starter · #1 ·
My friends
I have an elevator installation, 40hp soft start, 208v, 120a with 1/0 cu feeder and 200a cb/150a fuse. 250a inrush.
Any time elevator starts I have a noise at one section of the conduit. It feels like vibration with mecahinal stroke until inrush goes away.
I pulled wire out put 2/0 in noise still there. C/B or fuise does not trip.
Strangly enough they say it is more when it is cold!!!. I measured voltage at the time of noise it is 208-215. No noise or vibration transmiteed at the cables when touched inside j.box.
No major noise in elevator machine room, I even disconnected flex conduit from the controller but no change. Controller has no noise, breaker has no noise, only a certain point in conduit and including hangers.
Help me please.
 

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Although I have never experienced it myself, I have heard of situations where the conductors vibrate at motor startup.
 

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Same here. I worked at Soldier Field on the heat trace and we had a few that would slap the conductors in the pipe AUDIBLY. We fixed those, but every once in a while they would slam once and be done after that.
 

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Same here. I worked at Soldier Field on the heat trace and we had a few that would slap the conductors in the pipe AUDIBLY. We fixed those, but every once in a while they would slam once and be done after that.
How did you fix them?
 

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Discussion Starter · #5 ·
Although I have never experienced it myself, I have heard of situations where the conductors vibrate at motor startup.
thanks, my puzzle is that i was expecting like railrodas, any vibration due to conductor to be caaried to ends either at the panel end or at splice can but none was transmitting.
 

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Is this a snapping noise associated with conductors moving apart due to high currents and the resulting magnetic forces?

Or is this a vibration?

Vibration can be a result of harmonic distortion from the motor starter. A manufactures supplied in line filter can resolve this issue. Harmonic currents are very high during start up. I posted a wave form snap shot of this last week.
 

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Discussion Starter · #7 ·
Is this a snapping noise associated with conductors moving apart due to high currents and the resulting magnetic forces?

Or is this a vibration?

Vibration can be a result of harmonic distortion from the motor starter. A manufactures supplied in line filter can resolve this issue. Harmonic currents are very high during start up. I posted a wave form snap shot of this last week.

Thanks, Typically what i hear is a vibration on conduit for half a second and than a sound. It does not feel like a jerk an conductor that hits the conduit. It feel like garden hose with air bubles in it followed by a noise (or may be simultaneously).
 
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