Your Questions Answered: Electrical distribution systems (Source: Consulting-Specifying Engineer)

By Jeff Thomas and John Yoon

On June 15th, Jeff Thomas, LAN’s vice president and business group director, co-presented Consulting-Specifying Engineer magazine’s webcast on electrical distribution systems. The webcast helped electrical and nonelectrical engineers understand basic features when selecting, specifying and applying electrical distribution systems. To narrow the broad scope of electrical distribution, the discussion focused on practical considerations for specifying electrical distribution systems. Following the webcast, Jeff answered a number of questions from attendees such as:

How do you reduce harmonics?

Jeff Thomas: As we know, harmonics collect in the neutral conductor. There are a couple of strategies for handling harmonics. In all cases IEEE-519 is the standard we want equipment and systems to meet:

• Use delta-wye transformers to isolate the harmonics.
• Use harmonic mitigating transformers but do the research and see if you agree they’ll do what they advertise.
• Install harmonic traps (not very common, usually to correct a very specific problem).

How is high and ultrahigh voltage class defined?

Jeff Thomas: Again, it depends on who you ask. One source indicates for AC voltages, HV is 100-230 kilovolt, EHV is 230-800 kilovolt and UHV is above 800 kilovolts. UHV DC is typically 1,000 kilovolts.