harmonics

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jimbo123

Senior Member
Why would we get harmonics back to a lighting panel for the second time ?
We have a 3 phase 120/208 100 amp panel and notice we have 180 hz on the neutral leg. Can poor connections and overloads to any of the circuits be a cause of this ? The first time harmonics were found one electrician said he replaced the ballast which was the cause at that time and the neutral read 60hz. after the replacements.

Anyone have any other causes for 180hz.
 
Smart $

Smart $

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Perhaps the same reason as the first time... (ballast degradation?)

That said, it is not uncommon to have harmonics... the question is, to what extent? Simply confirming 180Hz presence doesn't mean much. What is the magnitude of the neutral current and how much is 60Hz versus 180Hz, although your meter indicating 180Hz is an indication the 180Hz magnitude is at least high enough for the meter to recognize. But I don't see how you can be certain with anything short of a power analyzer. If you want to track it down with your fluke, check individual circuits, then on any contributing circuit, check its individual loads.
 
ohmhead

ohmhead

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ORLANDO FLA
jimbo123 said:
Why would we get harmonics back to a lighting panel for the second time ?
We have a 3 phase 120/208 100 amp panel and notice we have 180 hz on the neutral leg. Can poor connections and overloads to any of the circuits be a cause of this ? The first time harmonics were found one electrician said he replaced the ballast which was the cause at that time and the neutral read 60hz. after the replacements.

Anyone have any other causes for 180hz.
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Well we all can read and google this but heres my own thoughts if a switch is bad you can have harmonics a bad connection can create harmonics .

Heres why if you take a circuit 120 volts and lets say you have a resistive load a lamp with a regular bulb in this simple circuit a bad contact or connection between can add freq to this circuit . Its the gap or connection thats arcing across the point of connection to pass current voltage builds up to pass or jump across this gap that has to make and break each cycle but its not at 60 cycles its making and breaking at a different freq could be higher than 60 cycles most fluke meters made are rated at 400 cycles standard so they can pick this up .

The gap between a switch or connection will multiply the freq up from the input in cycles anything which makes and breaks can effect harmonics online . In electronics when you close a switch in circuit you must use a special circuit in your switching circuit meaning a regular switch doesnt work well or it will bounce when the switch closes its called a de- bounce circuit its kinda the same with a ac switch but no one thinks about it but its there every time you open or close a regular switch in your home there at that moment you are adding to the world some harmonics .

We need to eliminate this how just a simple circuit on you single pole switch in your house could help if everyone in the world did this it would help the trash we see today but no one will its kinda like the way people think today no one cares .

Think of the number of people at this time flipping that switch right now at this time thats a lot of harmonics !
 
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Besoeker

Besoeker

Senior Member
Location
UK
jimbo123 said:
Why would we get harmonics back to a lighting panel for the second time ?
We have a 3 phase 120/208 100 amp panel and notice we have 180 hz on the neutral leg. Can poor connections and overloads to any of the circuits be a cause of this ? The first time harmonics were found one electrician said he replaced the ballast which was the cause at that time and the neutral read 60hz. after the replacements.

Anyone have any other causes for 180hz.
Click to expand...
Pretty much any single phase non-linear load results in third harmonic currents.
On a three phase supply they add in the neutral.
 
Electric-Light

Electric-Light

Senior Member
jimbo123 said:
Why would we get harmonics back to a lighting panel for the second time ?
We have a 3 phase 120/208 100 amp panel and notice we have 180 hz on the neutral leg. Can poor connections and overloads to any of the circuits be a cause of this ? The first time harmonics were found one electrician said he replaced the ballast which was the cause at that time and the neutral read 60hz. after the replacements.

Anyone have any other causes for 180hz.
Click to expand...

Poor connection would cause flickering, voltage drop and overheating/smoke from the point of poor connection.

You can't measure harmonics with a normal DMM. You need a proper PQA or a DMM with a built-in Lite-PQA (I think Metex or ExTech has something like that).

Commercial rated electronic ballasts are power factor corrected with most having less than 10% THD.

Blame screw-in CFLs and computers. CRTs are mostly gone, so each work station doing regular office work consumes around 100-200W and assume power factor of 0.5 to 0.6 with 100%+ THD unless they have power factor corrected PSUs.

What are the true RMS amp readings on L1,L2,L3 and N?
 
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jimbo123

Senior Member
I can not give the amp readings at this time . I can recall last week the neutral had about 30 amps. That all i can give now.
 
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