Triplen harmonics are divisible by 3 and cause problems on which circuits?

Triplen harmonics are divisible by 3 and cause problems on which circuits?

• A. 3Ø, 3-wire circuits
• B. 3Ø, 4-wire circuits
• C. Both
• D. None

Answer: (B)

Triplen harmonics are multiples of three (3rd, 9th, etc.) and, in a three-phase system, they appear in all three phases in phase with each other. When a neutral is present, those in-phase currents add in the neutral conductor instead of canceling, which can lead to excessive neutral current, overheating, nuisance tripping, and voltage distortion for line-to-neutral loads. In a 3-phase, 3-wire system there is no neutral to carry that extra current, so the neutral-related issues aren’t present in the same way. That makes circuits with a neutral—the 3Ø, 4-wire configurations—the ones where triplen harmonics cause the most trouble.

Triplen harmonics are multiples of three (3rd, 9th, etc.) and, in a three-phase system, they appear in all three phases in phase with each other. When a neutral is present, those in-phase currents add in the neutral conductor instead of canceling, which can lead to excessive neutral current, overheating, nuisance tripping, and voltage distortion for line-to-neutral loads. In a 3-phase, 3-wire system there is no neutral to carry that extra current, so the neutral-related issues aren’t present in the same way. That makes circuits with a neutral—the 3Ø, 4-wire configurations—the ones where triplen harmonics cause the most trouble.