Elevator Feeder Hum

[ARF]

I have a common 500kcm feeder serving a new 30hp elevator and an older 25hp feeder. The feeder has a significant hum when the 25hp elevator runs but not when the newer 30hp runs. Any ideas on cause and remedy would be appreciated.

 

[electricalperson]

if the feeder conductors hum its probably because of the large load. sometimes motors can cause conductors to vibrate when they kick on. if thats the cause then there shoudnt be anything to worry about. you can try to remove extra slack from the conductors as a possible fix

 

[mdshunk]

I've had pretty good luck with humming feeders by just turning off the disconnect, jerking them around back and fourth in the conduit in one direction or the other, then re-energizing them. I guess doing that rearranges them just enough to stop that kazoo effect. Worth a try, in any event. I don't know what you'll be able to do with 500's. Maybe not much. Give it a shot, anyhow.

 

[catchtwentytwo]

What's the vintage of the older motor? Newer ones are more efficient and that could account a larger starting load on the older vs the 30 HP. Do you have the nameplate data handy from both?

 

[brian john]

Is the elevator controller a electronic or motor generator?

Are both controllers the same type/manufacture?

 

[charlietuna]

are they hydraulic elevators ?

 

[ARF]

Elevator Feeder Hum

Brian john Both controllers are Electronic and of the same manufacture.

 

[ARF]

Elevator feeder hum

Elevator feeder hum

catchtwentytwo,
the older motor is circa 1940. Running amps on the older motor is 95amps at 208v and 92amps on the newer 30hp motor.
The humming is present when the older motor runs continuously even after start up ??? The humming isn't there when the newer unit runs.

 

[ARF]

Elevator feeder hum

Elevator feeder hum

Charlietuna,
No, both elevators are cable.

 

[ARF]

Elevator feeder hum

Elevator feeder hum

mdshunk/electricalperson,
the confusing part is that the hum is present even when only the one motor is running. The same load on the newer motor does not appear to have the same effect. Thanks for the input on slack conductors.