Premium Membership ♕

Save 50% on all EEP Academy courses with Enterprise Membership Plan and study specialized LV/MV/HV technical articles & guides.

Home / Technical Articles / Learn how to analyse and check wiring diagrams of a medium voltage switchgear

Introduction to wiring diagrams

As already written earlier regarding the LV switchboard, wiring diagrams are used to show the control and signalization principle of operation inside the switchboard. Usually, they are given in form of electrical circuits between two lines which are representing control voltage potentials. Of course, various types of signals can be transferred outside the switchboard, for the purpose of measuring, monitoring, or control, i.e. to be used for SCADA applications.

Learn how to analyse and check wiring diagrams of a medium voltage switchgear
Learn how to analyse and check wiring diagrams of a medium voltage switchgear

Within this article, we will be talking about wiring diagrams inside medium voltage (MV) switchgear. Basically, the same rules and principles apply here as well. However, there are some differences related to the fact that in the case of MV applications, primary equipment operates at medium voltage level, while control and signalization circuits are always of low voltage type.

An example of wiring diagram related to MV equipment will be given and discussed later within the article.

Table of content:

  1. The basics of MV switchgear
  2. Example of MV switchgear wiring diagram

1. The basics of MV switchgear

When we say “medium voltage” or just “MV” switchgear, we refer to a switchgear with “primary” equipment which operates at medium voltage level, typically at or close to 6 kV, 10 kV, 20 kV, and 35 kV in Europe. These are phase to phase, or “line” values of rated operation voltage.

Such switchgear will also contain so-called “secondary” equipment, used for control, measuring, signalization, and auxiliary purposes. So basically, MV switchgear consists of primary and secondary equipment.

Primary equipment is designed and used for rated voltage and current values specified for switchgear. These are medium voltage circuit breakers, switch disconnectors, fuses, surge arresters, measuring transformers, etc.

Secondary equipment is used for control and supervision of primary equipment, usually at 24 VDC, 48 VDC, 110 VDC, 115 VAC, or 230 VAC voltage levels. Protection and signalization relays, miniature circuit breakers, selector switches, auxiliary relays, signal lights, etc. are the example of secondary equipment.

Primary equipment is bulky, heavy, and expensive. It is placed inside the MV compartment, which can be further divided into a busbar compartment, circuit breaker compartment, cable compartment, etc. depending on content and topology.

Premium Membership Required

This technical article/guide requires a Premium Membership. You can choose an annually based Plus, Pro, or Enterprise membership plan. Subscribe and enjoy studying specialized technical articles, online video courses, electrical engineering guides, and papers. With EEP’s premium membership, you get additional essence that enhances your knowledge and experience in low- medium- and high-voltage engineering fields.

Check out each plan’s benefits and choose the membership plan that works best for you or your organization.

Good To Know!Save 50% on all video courses by purchasing Enterprise plan.

Log In »Purchase »

Premium Membership

Get access to premium HV/MV/LV technical articles, electrical engineering guides, research studies and much more! It helps you to shape up your technical skills in your everyday life as an electrical engineer.
More Information

Miodrag Kokotovic

Graduated from Faculty of Electrical Engineering, within University of Belgrade, in the field of electrical power systems. Expert in electrical part of tender preparation, design, procurement, construction and commissioning of treatment plants and pumping stations, electrical power quality and energy management.

Leave a Comment

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!

two  ×    =  four

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