Harmonics in Green Buildings

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T.M.Haja Sahib

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It is stated that in green buildings the harmonic producing electronic loads should not exceed 10% of total load to limit the electronic noise of harmonics. I do not know this is achievable. Your input please.
 
T.M.Haja Sahib said:
It is stated that in green buildings the harmonic producing electronic loads should not exceed 10% of total load to limit the electronic noise of harmonics. I do not know this is achievable. Your input please.
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Isn't anything possible if you throw enough money at it?
Slightly more seriously, yes, I think it's achievable.
 
Besoeker said:
Isn't anything possible if you throw enough money at it?
Slightly more seriously, yes, I think it's achievable.
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I simply adopted your own country philosopher Sir Bertrand Russeli's statement that some American millionaires think themselves as gods, implying that with their huge amount of money nothing is difficult to them.
More seriously, I am wondering. with high proliferation of single phase harmonic producing electronic loads in any building, how it could be possible to contain them within 10%.
 
T.M.Haja Sahib said:
I simply adopted your own country philosopher Sir Bertrand Russeli's statement that some American millionaires think themselves as gods, implying that with their huge amount of money nothing is difficult to them.
More seriously, I am wondering. with high proliferation of single phase harmonic producing electronic loads in any building, how it could be possible to contain them within 10%.
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I would think it more important to use mitigating measures to prevent the harmonics from polluting the supply network to the building rather than puting a limit on harmonic producing load within it.
However, there are ways and means to reduce the harmonics produced by any piece of kit. You mentioned a sine wave input SMPS in another thread. Use that technique in all electronic gizmos - job done. More expensive but done.
An alternative approach is to run things like computers from a UPS (we do our servers that way) with a sine wave input.
Any drives van be active front end.
Anything can have a passive harmonic filter included at its input.

And, I ought to ask you what the 10% refers to? Power rating? Current distortion? They're not the same thing.
 
"Anything can have a passive harmonic filter included at its input."

Thats the best answer. Unless you want to remove all of the electronic equipment, VFD's and T8 lighting, you will have harmonics issue. A good way to counter the effects are with filters.
 
aelectricalman said:
Unless you want to remove all of the electronic equipment, VFD's and T8 lighting, you will have harmonics issue. A good way to counter the effects are with filters.
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Besoeker said:
Anything can have a passive harmonic filter included at its input.
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Unfortunately, it increases the energy consumption due to energy loss in the filter which seems to run against the principles of Green building.
Besoeker said:
And, I ought to ask you what the 10% refers to?
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The answer is in the first post of the thread. I thought the thread had continuity.
 
T.M.Haja Sahib said:
Unfortunately, it increases the energy consumption due to energy loss in the filter which seems to run against the principles of Green building.
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Any harmonic mitigating measure is probably going to do that and add costs. Think about active front end variable frequency inverter drives. The front end bridge changes from a plain rectifier to an IGBT bridge of about the same rating as the output bridge. More complex, more losses, and more expensive.


T.M.Haja Sahib said:
The answer is in the first post of the thread.
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should not exceed 10% of total load
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It what you put in the first thread. Your post doesn't make that clear.
But 10% of what load?
Installed kVA?
kW?
Current?

For example if you had had 100kW of fixed speed motors installed, could you then have only 10kW worth of variable speed drives?
Of course the ratio of the currents between the VSDs and the fixed motors is most probably going to be rather lower than 10%.
And it the non-sinusoidal current that causes voltage distortion.

All I'm asking is that you clarify what the 10% refers to.
 
the IEEE standard for Harmonic total demand distortion ITDD at 5% should be more than enough to satisfy any "green building" requirement.

this is the limit that utilities use in measuring harmonic emissions from customers.
 
Besoeker said:
Any harmonic mitigating measure is probably going to do that and add costs. Think about active front end variable frequency inverter drives. The front end bridge changes from a plain rectifier to an IGBT bridge of about the same rating as the output bridge. More complex, more losses, and more expensive.
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I think there are SMPS with input filter less design that may serve the purpose here.

Besoeker said:
It what you put in the first thread. Your post doesn't make that clear.
But 10% of what load?
Installed kVA?
kW?
Current?

For example if you had had 100kW of fixed speed motors installed, could you then have only 10kW worth of variable speed drives?
Of course the ratio of the currents between the VSDs and the fixed motors is most probably going to be rather lower than 10%.
And it the non-sinusoidal current that causes voltage distortion.

All I'm asking is that you clarify what the 10% refers to.
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Let us take the name plate ratings and in that case, installed KVA, KW and current are all equivalent.
 
robbietan said:
the IEEE standard for Harmonic total demand distortion ITDD at 5% should be more than enough to satisfy any "green building" requirement.

this is the limit that utilities use in measuring harmonic emissions from customers.
Click to expand...

I think the 5% refers to voltage harmonic. Current harmonic limit may be much higher.
 
T.M.Haja Sahib said:
Let us take the name plate ratings and in that case, installed KVA, KW and current are all equivalent.
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As an example take a 55kW 400V 3-phase motor.
Driven directly from the supply it will take about 107A FLC
Use an active front end and that will take about 89A.

Both 55kW rating.
The supply loading for one is 74 kVA, the other 62 kVA.
The supply power is 59kW for one and 62kW for the other.

Would you perhaps like to reconsider your comment that installed KVA, KW and current are all equivalent?
 
Besoeker said:
As an example take a 55kW 400V 3-phase motor.
Driven directly from the supply it will take about 107A FLC
Use an active front end and that will take about 89A.

Both 55kW rating.
The supply loading for one is 74 kVA, the other 62 kVA.
The supply power is 59kW for one and 62kW for the other.

Would you perhaps like to reconsider your comment that installed KVA, KW and current are all equivalent?
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Does not the name plate rating distinguish between the two?
 
You mentioned about two motors: one with active front end while the other one without it. If the one with the active front one is so provided in the field, such modification in its rating need be clearly displayed.
 
Besoeker said:
As an example take a 55kW 400V 3-phase motor.
Driven directly from the supply it will take about 107A FLC
Use an active front end and that will take about 89A.

Both 55kW rating.
The supply loading for one is 74 kVA, the other 62 kVA.
The supply power is 59kW for one and 62kW for the other.

Would you perhaps like to reconsider your comment that installed KVA, KW and current are all equivalent?
Click to expand...

I am trying to learn from these posts sir; can you post how you arrived at each value above please? thank you.
 
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