Search

Premium Membership ♕

Limited Time Offer: Save 15% on PRO Plan with discount code: LRN15 and study specialized LV/MV/HV technical articles and studies.

Conductors and protection devices

Careful selection of the conductors sizes in wiring systems and the characteristics of protection devices will ensure basic protection of the installation.

Guide to sizing conductors and selecting protection devices
Guide to sizing conductors and selecting protection devices (photo credit: brainfiller.com)

Basic protection of the installation:

  1. Protection against overloads
  2. Limitation of voltage drops
  3. Protection against short-circuits
  4. Checking of the thermal stresses
  5. Protection against indirect contact

The complete calculation of installations has been found to be so long, complex, and even daunting as to justify the ongoing development of practical aids: calculation charts, note-boards, etc. and now software, such as XL PRO2 Calculation.

We must not however let the absolute accuracy, reliability and ease of use of these tools make us lose sight of the calculation principles on which they are based!

The purpose of this book is to cover the main rules that are used for sizing conductors, wiring systems and their electrical protection (against overloads, voltage drops, short-circuits and indirect contact) according to the parameters of the installation:

  • Physical
    (type of conductor, installation conditions, temperature, length of lines, etc.)
  • Electrical
    (power, prospective short-circuit, operating currents, etc.).
conductor supplying a group of circuits and applications
conductor supplying a group of circuits and applications

Examples of how they are determined are given for each parameter. The complete process for estimating the short-circuit currents at all levels in the installation is illustrated on page 54.

The rules for selecting and mounting wiring systems are specified in standard IEC 60364-5-52CENELEC guide R064-003 gives a rigorous calculation method suitable for calculation software. In practice two approximate methods are used. These are called the conventional method and the composition method.


Overcurrents

Overloads

An overload is an overcurrent circulating when there is no electrical fault in a circuit. It is caused by under-sizing of the wiring system for the load being supplied, or by the load being too high for the wiring system.

Protection devices must be provided to break any overload current before the overheating of the conductor damages its insulation, its connections and the surrounding equipment.

Protection against overloads can be provided by fuses (type gG), circuit breakers with thermal or electronic release or contactors with measurement relays. aM fuses do not provide protection against overloads. The rules for determining overload protection are described on page 06.

Title:Sizing conductors and selecting protection devices – Legrand
Format:PDF
Size:4.4 MB
Pages:71
Download:Right here | Video Courses | Membership | Download Updates
Sizing conductors and selecting protection devices - Legrand
Sizing conductors and selecting protection devices – Legrand

Premium Membership

Get access to premium HV/MV/LV technical articles, advanced electrical engineering guides, papers, and much more! It will help you to shape up your technical skills in your everyday life as an electrical engineer.
50% Discount 💥 - Save 50% on all 90+ video courses with Enterprise Membership plan.

More Information

One Comment


  1. tarekdia
    Feb 06, 2019

    thanks

Leave a Reply to tarekdia

Tell us what you're thinking. We care about your opinion! Please keep in mind that comments are moderated and rel="nofollow" is in use. So, please do not use a spammy keyword or a domain as your name, or it will be deleted. Let's have a professional and meaningful conversation instead. Thanks for dropping by!

eight  +  two  =  

Learn How to Design Power Systems

Learn to design LV/MV/HV power systems through professional video courses. Lifetime access. Enjoy learning!

Subscribe to Weekly Newsletter

Subscribe to our Weekly Digest newsletter and receive free updates on new technical articles, video courses and guides (PDF).
EEP Academy Courses - A hand crafted cutting-edge electrical engineering knowledge