Copper Bus Bars Humm

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nasir mehmood

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There are 5 cubicals installed which are main Incomer, Phase Correction, Sync1, Sync 2 and ATS from right to left in one row. Copper Bus Bars of 1600 Amps 3P+N and E are running in them. when load reaches upto 800Amps they sounds/ humm very loudely while the Neutral Bus is also grounded separately with 2x70 mm2 single core copper PVC cable.

How this humm can removed/corrected?
Why Humm?
 
Well is this a old switchboard or a new switchboard ?

Heres a example of humming new switchboard 5000amp main 4 sections the shunt trip was tested at full load after shunt was tested the electrician did not reset the 120 volt shunt trip button .

Next he recharged the breaker and pushed closed as the breaker could not fully close it tripped when it did the current flowing from contact to contact in that breaker was high and the second it took to trip heated the breaker up distorted the breaker contacts .

This is a true story next the switchboard after reset of shunt and now turning on power again breaker reset the swb had a load humming.

Square D was called out this was new equipment the breaker was replaced it transfered the vibration thur out the switchboard .


Its called stress if a switchboard is stressed or heated or say has a bad connection it will hum loudly .




Question is this a normal 60 hz ac hum like iwire said or is this a very loud hum theres a difference ?
 
iwire said:
Stop using AC and start using DC.

I am no engineer but it is my understanding hum is by product of the frequency and is more pronounced when currents are approaching the capacity of the conductors.
Click to expand...

It is the physical realignment of the domains every 1/60th of a second. The billions of domains moving causes a vibration that is heard as a hum. Another useless peice of knowledge, it is nearly a perfect C flat tone.
 
Well just wonding why the 5000 amp switchboard next to it didnt make a sound i guess if we had a harmonic of 3 4 or 5th we could hear a tune playing ?

I need to look into this its interesting what we all think on vibration of a wire or buss bar .

And how a human ear can hear changes in polar domains in metal .
 
ohmhead said:
And how a human ear can hear changes in polar domains in metal .
Click to expand...

Imagine what some animals hear. Our cat absolutely hates the vacuum.
It might be he hears 12amps worth of domains changing,

or could it be the time my son tried to speed up his job of brushing
the cat by using the vacuum on his fur.

As to the OP, something could be loose (not tightened quite enough) if
the hum has increased significantly over time with the same load.

Has regular PM been done on the buss bar bolts? lugs? All torqued to spec?
 
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Well imuse97 looking at it i found this the sound we hear can only be from air movement if there is no air there is no sound .

Sound travels in air not space .
If one can hear whats going on internally in metal why do we need ultrasound.

I read this when a conductive material is subjected to a time changing magnetic field eddy currents are formed in the conductor itself.

These cirrulate inside and a magnetic field is formed the force can be considered dynamic a continuously changing field significant forces are applied a opposong field of change exist between forces due to main field to internal field of eddys in addition outside factors of heat or temp will increase the force in conductor movement in magnitude.

Sound can be the result of air movement do to a vibration of conducting materials and magnetic fields applied but is not heard by the human ear as it is minimal in nature .

Utrasound testing of metal in research has been able to detect this movement only .
These test were at high amperage on buss bars to check for cracks and design new support methods of bus bars under stress at low freqs of 60 cycles .

IMO i think we better get our ears checked if we hear humming do to eddys or changing domains .

And my dogs attack the vac its one of those round disk jobs .

Take care
 
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