From http://ecmweb.com/mag/electric_fundamentals_harmonics/ :
Triplen harmonics are third-order harmonics created by devices that draw current from the line in a non-sinusoidal waveform. These devices are known as non-linear loads and include phase-control dimmers and switch-mode power supplies.
Triplen harmonics are odd multiples of the 3rd harmonic of the fundamental (50 or 60 Hz): 3rd, 9th, 15th, 21st. etc. Triplen harmonics are of the zero-sequence variety, which means that they add rather than cancel in the neutral. This can result in neutral conductor overcurrents, as well as transformer overheating.
Of importance in our industry as they're responsible for, in a three phase, Wye-connected system, current on the neutral that can exceed any one line current by as much as 30% when used with Dimmer, phase control. For example, a three phase dimming system with a connected load of 100A per phase could achieve a neutral current of 130A at certain combinations of dimmer settings. Thusly the use of double-neutral connections to handle the current. It's also why a grounded conductor (neutral) on phase-control systems must be considered current-carrying for calculation of conduit fill and ampacity adjustment factor .
Triplen harmonics are third-order harmonics created by devices that draw current from the line in a non-sinusoidal waveform. These devices are known as non-linear loads and include phase-control dimmers and switch-mode power supplies.
Triplen harmonics are odd multiples of the 3rd harmonic of the fundamental (50 or 60 Hz): 3rd, 9th, 15th, 21st. etc. Triplen harmonics are of the zero-sequence variety, which means that they add rather than cancel in the neutral. This can result in neutral conductor overcurrents, as well as transformer overheating.
Of importance in our industry as they're responsible for, in a three phase, Wye-connected system, current on the neutral that can exceed any one line current by as much as 30% when used with Dimmer, phase control. For example, a three phase dimming system with a connected load of 100A per phase could achieve a neutral current of 130A at certain combinations of dimmer settings. Thusly the use of double-neutral connections to handle the current. It's also why a grounded conductor (neutral) on phase-control systems must be considered current-carrying for calculation of conduit fill and ampacity adjustment factor .
