Neutral Sizing in Harmonic Rich Installations

Both national and international standards for the conductor sizing of cables do not adequately take into account the additional heat load arising from harmonic currents. Some standards prescribe the maximum current values for four-conductor and five-conductor cables under the assumption that only two or three conductors are loaded. However, today’s harmonic situations may give rise to the fourth conductor (neutral) being fully loaded or even overloaded simultaneously with a balanced load on the three phase conductors. Other standards provide a general instruction that under a particular harmonic impact on the phase conductors, a certain additional load has to be taken into account for sizing the neutral conductor. However, the practitioner will usually not know how much harmonic impact arises from a particular load or group of loads.

In the following application note, an approach will be given to estimate the additional thermal impact due to harmonic currents in the LV power supply system of a building. Based on this estimation, it provides a methodology on how to dimension and select three-phase cables that are supposed to feed single-phase final circuits containing distorting loads.

The Highlights from this publication:

  • The harmonic impact on the neutral current can be substantial. Cables have to be over-dimensioned accordingly.
  • Assuming that all harmonics accumulate in the neutral results in an approach that falls on the safe side.
  • It is good to keep this safety margin, because similar loads can have a very different harmonic behaviour.
  • It is also good to provide some reserve for imbalance coming on top of the harmonics.

DOWNLOAD RESOURCES

Application Note - Neutral Sizing in Harmonic Rich Installations

Related POST

Reactive Power Compensation - Understanding the positive and negative sides - An Expert's View

‘Reactive Power’ – is it for real or imaginary? is it unavoidable or essential? a problem or a solut..

Read more

Innovations in PQ Interventions

Power Quality is one of the major issues in electricity distribution segment today. It is an issue, ..

Read more

Interactive Workshop on Power Quality and Harmonics at Mumbai

APQI and MSEDCL jointly hosted a full day interactive workshop on Harmonics and Power Quality at Mum..

Read more

Workshop on Power Quality and Its Impact On Steel Re-Rolling Mill Infrastructue at Raipur and Nagpur

Asia Power Quality Initiative (APQI) & Visvesvaraya National Institute of Technology (VNIT) in assoc..

Read more

Unbalances, harmonics & neutral current in an Indian Airport Lighting system? a study to evolve suitable solutions.

Unbalances, harmonics & neutral current in an Indian Airport Lighting system? a study to evolve suit..

Read more

Fundamental of Harmonics and Study of its Impact on Electrical Power System

Voltage and current functions are the foundation concepts in the power system. Nonlinear devices li..

Read more

10th Webinar Assessing Transformer Loss in Harmonics High Environment

17th November, 2016 (Thursday) - Transformers are one of the most important and high CAPEX assets..

Read more

18th Webinar - kVAh Billing - the 4 things you must know to optimize energy bills

30th July, 2020(Thursday) - After implementation of the kVAh tariff structure by MSEDCL in April 202..

Read more
Drop us a message

You're in the right place! Just drop us a message. How can we help?

Or see contact page
There seems to be some problem with validating your request. Please try again.
Thank You! Your message has been delivered.