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#166310 - 07/17/07 06:51 PM Humming in Cubicle of Medium Voltage Switchgear  
windmiller  Offline
Junior Member
Joined: Dec 2006
Posts: 43
Alaska
Hi,
I have noticed a humming that recently started in a section of medium voltage switchgear. it operates at 13.8 kV.

Could this be a harmonic imbalance or loose bus bar?

Thanks for any replies.

regards

Windmiller


We all live under one King

Work Gear for Electricians and the Trades

#166327 - 07/18/07 06:59 AM Re: Humming in Cubicle of Medium Voltage Switchgear [Re: windmiller]  
Zog  Offline
Member
Joined: Sep 2005
Posts: 120
Charlotte, NC
Yes, could be either of those or you could have tracking. If you can arrange a shutdown do it as soon as possible. A visual inspection of all insulating surfaces should be done looking for signs of tracking, use a black light for the inspection that will make it easier to find any traces of nitric acid.
If you cant shut down a visual inspection with a corona camera would be best.


MV/HV Testing Specialist, "BKRMAN"

#217356 - 06/24/16 07:46 AM Re: Humming in Cubicle of Medium Voltage Switchgear [Re: windmiller]  
highvoltpower  Offline
New Member
Joined: Jun 2016
Posts: 1
India
Surely, listen for popping, or cracking sounds produced by electrical discharges also humming sounds or vibration produced by quality. With lights out, look for blue or purple corona halos. Orange or red sputter arcs are created by intermittent sparking. Best way is you cannot blackout a graphic checkup with a halo.


#217357 - 06/24/16 10:37 AM Re: Humming in Cubicle of Medium Voltage Switchgear [Re: windmiller]  
twh  Offline
Member
Joined: Mar 2004
Posts: 905
Regina, Sask.
Thermal imaging is a nice way to find problems like loose connections. The heat stays for a while after it's turned off so you have some time to look around.



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