Harmonic Control in Consumer System

[HamidEle]

Normally, Utilties have certain rules to limit THD at the common coupling limits. It is required by any companies.

Is there any rules on consumer side to limit the harmonic levels, especialy at low voltage levels?
CEC doesn't have any requiements? What about NEC?

 

[magoo2]

Normally the North American utilities follow IEEE 519 which puts a current harmonic limit on the customer so that the resulting voltage distortion isn't excessive.

There is no NEC requirement to my knowledge.

 

[HamidEle]

Thanks for the reply. Utilities put limits on the consumer sides.What about within the power system?

 

[pablo51]

I think the only limits for the are those that may have been written into either the corporation commission's edicts or the actual contract with the customer... having said that, the utility has concerns with providing a service that provides good quality to their customers... afterall, complaints back to the commissions can be detrimental in many ways -- for non-investor owned utilities, the jobs of the commissioners or utility personnel can be on the line..

again, my experience is that most (not all) problems w/ THD come from the customers' side, reflecting back onto the system... for instance a bank of spot welders at a local manufacturing facility can create havoc on other customers on that line.. it's to everyones interests then for the manufacturer to address the problem, and the utility is often willing to help (esp. if there is added revenue involved)...

if you are having problems, contact your utility... they should be able narrow down the problem to your side or potentially another customer in your area... and if there a number of customers having problems, it will get addressed fairly quickly (but allow some time)

Please note that not all "power quality" problems come through the utility wires... I am aware of one power quality issue, where a customer's computer system kept crashing, etc. and of course the utility was the likely suspect.. After several weeks of investigation, it was determined that the professional office next door didn't have radiation barriers in the walls -- every time they took an x-ray, the customer's computers went berserk... the issue was rectified immediately..

 

[HamidEle]

So, we do have to solve the problems within our systems because the potential harmonics will affect the power quality we are designing even though it may not affect other customers the same utility is serving.