Help
  • Explore Community
  • Get Started
  • Ask the Community
  • How-To & Best Practices
  • Contact Support
Notifications
Login / Register
Community
Community
Notifications
close
  • Forums
  • Knowledge Center
  • Events & Webinars
  • Ideas
  • Blogs
Help
Help
  • Explore Community
  • Get Started
  • Ask the Community
  • How-To & Best Practices
  • Contact Support
Login / Register
Sustainability
Sustainability

We Value Your Feedback!
Could you please spare a few minutes to share your thoughts on Cloud Connected vs On-Premise Services. Your feedback can help us shape the future of services.
Learn more about the survey or Click here to Launch the survey
Schneider Electric Services Innovation Team!

What is behind Full Selectivity, Total Selectivity, and Enhanced Selectivity ?

Power Distribution and Digital Support

Join experts & peers to learn, share and engage about the key trends of electrical distribution around safety, availability, efficiency and connectivity, as well as power standards & regulations. From design to implementation and operation, let’s discuss how digital and software are transforming your business and your day-to-day work.

cancel
Turn on suggestions
Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type.
Showing results for 
Show  only  | Search instead for 
Did you mean: 
  • Home
  • Schneider Electric Community
  • Power Distribution IEC
  • Power Distribution and Digital Support
  • What is behind Full Selectivity, Total Selectivity, and Enhanced Selectivity ?
Options
  • Subscribe to RSS Feed
  • Mark Topic as New
  • Mark Topic as Read
  • Float this Topic for Current User
  • Bookmark
  • Subscribe
  • Mute
  • Printer Friendly Page
Invite a Co-worker
Send a co-worker an invite to the portal.Just enter their email address and we'll connect them to register. After joining, they will belong to the same company.
You have entered an invalid email address. Please re-enter the email address.
This co-worker has already been invited to the Exchange portal. Please invite another co-worker.
Please enter email address
Send Invite Cancel
Invitation Sent
Your invitation was sent.Thanks for sharing Exchange with your co-worker.
Send New Invite Close
Top Experts
User Count
Genghiz
Captain Genghiz Captain
93
Gregoire_Brun
Commander Gregoire_Brun Commander
71
J_Travostino
Sisko J_Travostino Sisko
70
S-W
Commander S-W Commander
66
View All

Invite a Colleague

Found this content useful? Share it with a Colleague!

Invite a Colleague Invite
Solved Go to Solution
Back to Power Distribution and Digital Support
Solved
MercedesLopez
Ensign MercedesLopez
Ensign

Posted: ‎2019-12-12 06:39 AM

0 Likes
4
8086
  • Mark as New
  • Bookmark
  • Subscribe
  • Mute
  • Subscribe to RSS Feed
  • Permalink
  • Print
  • Email to a Friend
  • Report Inappropriate Content

Link copied. Please paste this link to share this article on your social media post.

Posted: ‎2019-12-12 06:39 AM

What is behind Full Selectivity, Total Selectivity, and Enhanced Selectivity ?

I am confused between the different ways selectivity is defined.
Could you please clarify what is the difference between Full Selectivity,  Total Selectivity, and  Enhanced Selectivity ?

Reply

Link copied. Please paste this link to share this article on your social media post.

  • All forum topics
  • Previous Topic
  • Next Topic

Accepted Solutions
MathieuGuillot
Lieutenant MathieuGuillot Lieutenant
Lieutenant

Posted: ‎2019-12-18 07:54 AM

2 Likes
1
8052
  • Mark as New
  • Bookmark
  • Subscribe
  • Mute
  • Subscribe to RSS Feed
  • Permalink
  • Print
  • Email to a Friend
  • Report Inappropriate Content

Link copied. Please paste this link to share this article on your social media post.

Posted: ‎2019-12-18 07:54 AM

Hello,

 

Thanks for this relevant question. I understand it can be confusing indeed.

 

Selectivity (or discrimination) is achieved by overcurrent and earth fault protective devices if a fault condition, occurring at any point in the installation, is cleared by the protective device located immediately upstream of the fault, while all other protective devices remain unaffected.

 

This is the main objective : minimize the part of installation switched off in case of fault such as overload, Line to Line short-circuit or Line to Earth fault.  The concern is to convert this general requirement in criteria for circuit-breakers selection.

 

 

Selectivity is achieved when the maximum short-circuit current at a point of installation (Isc_max) is below selectivity limit (Is) of the circuit breakers supplying this point of installation. That’s where Total / Full / Enhanced selectivity concepts come in the game… IEC 60364-5-53: 535 2019 is now providing some guidance.

 

If we consider two circuit-breakers, the following situations are possible:

 

  1. Is < Icu or Icn : The selectivity limit (Is) between the two circuit-breakers is lower than the breaking capacity of the circuit-breaker on the load side (Icu or Icn). (In that case we talk about “Partial selectivity” between the two circuit-breakers.)

 

Example: ComPact NSX100F (36kA 400V) TMD 100A & iC60N (10kA 40V) C 32A Selectivity limit Is = 1kA

 

In a given electrical installation two cases are then possible:

 

  • Is < Isc_max <= Icu or Icn : The maximum short-circuit current on the load side (Isc_max) is higher than this selectivity limit “Is”. (1kA in the example). In that case selectivity will not be achieved for all values of fault current. We call this situation “partial selectivity” in the installation and partial selectivity for circuit-breakers.

 

  • Isc_max <= Is < Icu or Icn : The maximum short-circuit current on the load side is lower or equal to this selectivity limit Is. (1kA in the example). In that case we talk about “Full selectivity” in the installation even if it’s partial from circuit-breaker perspective.

  1. Isc_max < Is = Icu or Icn The selectivity limit (Is) between the two circuit-breakers is equal to the breaking capacity of the circuit-breaker on the load side and the maximum short-circuit current on the load side is lower or equal to this breaking capacity. In that case we talk about “Total selectivity” in the installation and total selectivity for circuit-breakers.

Example: ComPact NSX100F (36kA 400V) Micrologic 2.2 100A & iC60N (10kA 40V) C 32A: Total selectivity

 

 

  1. Icu<  Isc_max <= Icomb The maximum short-circuit current on the load side is higher than the breaking capacity of the circuit-breaker on the load side when using back up (or cascading) effect as permitted by IEC 60364-4-43 Ed 3 2008 § 434.5.1 or equivalent national standards such as BS7671, NFC15100. In that case the maximum short-circuit current shall be lower than the re-enforced breaking capacity (Icomb). The selectivity limit between the two circuit breakers in that specific case can also be enhanced or not according to manufacturer information. If selectivity limit is going above Icu of downstream circuit-breaker it ’is called “Enhanced selectivity” in the installation and enhanced selectivity for circuit-breakers.

 

Example: ComPact NSX100F (36kA 400V) Micrologic 100A & iC60N (10kA 40V) C 32A “20/20”

  • Enhanced selectivity limit = 20kA
  • Enhanced breaking capacity = 20kA

 

 

To wrap up :

 

Selectivity in a given installation according to circuit-breakers selectivity performance without back-up

 

Selectivity characteristics of two circuit-breakers

Short-circuit current

Selectivity consequence for the electrical installation

Partial (up to Is)

Is<= Isc max <= Icu or Icn

Partial up to Is

Isc max < Is<= Icu or Icn

Full

 

Total

 

Isc max <= Is=  Icu or Icn

 

Total

 

 

Selectivity in a given installation according to circuit-breakers selectivity performance when back-up  is used:

 

Selectivity characteristics of two Circuit-breakers

Short-circuit current

Selectivity consequence for  the electrical installation

Partial (up to Is)

Is < Icu < Isc max

Partial (up to Is)

Total

Is = Icu < Isc max

Partial (up to Icu)

Enhanced

Icu < Isc max <= Is

Enhanced selectivity (up to Is_enhanced)

 

 

From a designer perspective, when selectivity in an electrical installation is expected I recommend to specify the following : Either “Total Selectivity is required and back-up is forbidden” or “Total selectivity is required, if back-up is applied, enhanced selectivity up to maximum short-circuit current shall be checked.  

 

Mathieu Guillot

Schneider Electric

See Answer In Context

Reply

Link copied. Please paste this link to share this article on your social media post.

MathieuGuillot
Lieutenant MathieuGuillot Lieutenant
Lieutenant

Posted: ‎2019-12-18 07:59 AM

In response to MathieuGuillot
2 Likes
0
8051
  • Mark as New
  • Bookmark
  • Subscribe
  • Mute
  • Subscribe to RSS Feed
  • Permalink
  • Print
  • Email to a Friend
  • Report Inappropriate Content

Link copied. Please paste this link to share this article on your social media post.

Posted: ‎2019-12-18 07:59 AM

Sorry a "cell jam" makes my first table confusing. Read as follow:

 

Selectivity in a given installation according to circuit-breakers selectivity performance without back-up (cascading)

 

Selectivity characteristics of two Circuit-breakers

Short-circuit current

Selectivity consequence for the electrical installation

Partial (up to Is)

Is<= Isc max <= Icu or Icn

Partial up to Is

Partial (up to Is)

Isc max < Is<= Icu or Icn

Full

 

Total

 

Isc max <= Is=  Icu or Icn

 

Total

 

 

See Answer In Context

Reply

Link copied. Please paste this link to share this article on your social media post.

Replies 4
MathieuGuillot
Lieutenant MathieuGuillot Lieutenant
Lieutenant

Posted: ‎2019-12-18 07:54 AM

2 Likes
1
8053
  • Mark as New
  • Bookmark
  • Subscribe
  • Mute
  • Subscribe to RSS Feed
  • Permalink
  • Print
  • Email to a Friend
  • Report Inappropriate Content

Link copied. Please paste this link to share this article on your social media post.

Posted: ‎2019-12-18 07:54 AM

Hello,

 

Thanks for this relevant question. I understand it can be confusing indeed.

 

Selectivity (or discrimination) is achieved by overcurrent and earth fault protective devices if a fault condition, occurring at any point in the installation, is cleared by the protective device located immediately upstream of the fault, while all other protective devices remain unaffected.

 

This is the main objective : minimize the part of installation switched off in case of fault such as overload, Line to Line short-circuit or Line to Earth fault.  The concern is to convert this general requirement in criteria for circuit-breakers selection.

 

 

Selectivity is achieved when the maximum short-circuit current at a point of installation (Isc_max) is below selectivity limit (Is) of the circuit breakers supplying this point of installation. That’s where Total / Full / Enhanced selectivity concepts come in the game… IEC 60364-5-53: 535 2019 is now providing some guidance.

 

If we consider two circuit-breakers, the following situations are possible:

 

  1. Is < Icu or Icn : The selectivity limit (Is) between the two circuit-breakers is lower than the breaking capacity of the circuit-breaker on the load side (Icu or Icn). (In that case we talk about “Partial selectivity” between the two circuit-breakers.)

 

Example: ComPact NSX100F (36kA 400V) TMD 100A & iC60N (10kA 40V) C 32A Selectivity limit Is = 1kA

 

In a given electrical installation two cases are then possible:

 

  • Is < Isc_max <= Icu or Icn : The maximum short-circuit current on the load side (Isc_max) is higher than this selectivity limit “Is”. (1kA in the example). In that case selectivity will not be achieved for all values of fault current. We call this situation “partial selectivity” in the installation and partial selectivity for circuit-breakers.

 

  • Isc_max <= Is < Icu or Icn : The maximum short-circuit current on the load side is lower or equal to this selectivity limit Is. (1kA in the example). In that case we talk about “Full selectivity” in the installation even if it’s partial from circuit-breaker perspective.

  1. Isc_max < Is = Icu or Icn The selectivity limit (Is) between the two circuit-breakers is equal to the breaking capacity of the circuit-breaker on the load side and the maximum short-circuit current on the load side is lower or equal to this breaking capacity. In that case we talk about “Total selectivity” in the installation and total selectivity for circuit-breakers.

Example: ComPact NSX100F (36kA 400V) Micrologic 2.2 100A & iC60N (10kA 40V) C 32A: Total selectivity

 

 

  1. Icu<  Isc_max <= Icomb The maximum short-circuit current on the load side is higher than the breaking capacity of the circuit-breaker on the load side when using back up (or cascading) effect as permitted by IEC 60364-4-43 Ed 3 2008 § 434.5.1 or equivalent national standards such as BS7671, NFC15100. In that case the maximum short-circuit current shall be lower than the re-enforced breaking capacity (Icomb). The selectivity limit between the two circuit breakers in that specific case can also be enhanced or not according to manufacturer information. If selectivity limit is going above Icu of downstream circuit-breaker it ’is called “Enhanced selectivity” in the installation and enhanced selectivity for circuit-breakers.

 

Example: ComPact NSX100F (36kA 400V) Micrologic 100A & iC60N (10kA 40V) C 32A “20/20”

  • Enhanced selectivity limit = 20kA
  • Enhanced breaking capacity = 20kA

 

 

To wrap up :

 

Selectivity in a given installation according to circuit-breakers selectivity performance without back-up

 

Selectivity characteristics of two circuit-breakers

Short-circuit current

Selectivity consequence for the electrical installation

Partial (up to Is)

Is<= Isc max <= Icu or Icn

Partial up to Is

Isc max < Is<= Icu or Icn

Full

 

Total

 

Isc max <= Is=  Icu or Icn

 

Total

 

 

Selectivity in a given installation according to circuit-breakers selectivity performance when back-up  is used:

 

Selectivity characteristics of two Circuit-breakers

Short-circuit current

Selectivity consequence for  the electrical installation

Partial (up to Is)

Is < Icu < Isc max

Partial (up to Is)

Total

Is = Icu < Isc max

Partial (up to Icu)

Enhanced

Icu < Isc max <= Is

Enhanced selectivity (up to Is_enhanced)

 

 

From a designer perspective, when selectivity in an electrical installation is expected I recommend to specify the following : Either “Total Selectivity is required and back-up is forbidden” or “Total selectivity is required, if back-up is applied, enhanced selectivity up to maximum short-circuit current shall be checked.  

 

Mathieu Guillot

Schneider Electric

Reply

Link copied. Please paste this link to share this article on your social media post.

MathieuGuillot
Lieutenant MathieuGuillot Lieutenant
Lieutenant

Posted: ‎2019-12-18 07:59 AM

In response to MathieuGuillot
2 Likes
0
8052
  • Mark as New
  • Bookmark
  • Subscribe
  • Mute
  • Subscribe to RSS Feed
  • Permalink
  • Print
  • Email to a Friend
  • Report Inappropriate Content

Link copied. Please paste this link to share this article on your social media post.

Posted: ‎2019-12-18 07:59 AM

Sorry a "cell jam" makes my first table confusing. Read as follow:

 

Selectivity in a given installation according to circuit-breakers selectivity performance without back-up (cascading)

 

Selectivity characteristics of two Circuit-breakers

Short-circuit current

Selectivity consequence for the electrical installation

Partial (up to Is)

Is<= Isc max <= Icu or Icn

Partial up to Is

Partial (up to Is)

Isc max < Is<= Icu or Icn

Full

 

Total

 

Isc max <= Is=  Icu or Icn

 

Total

 

 

Reply

Link copied. Please paste this link to share this article on your social media post.

Anonymous user
Not applicable

Posted: ‎2019-12-24 11:14 PM

0 Likes
0
8028
  • Mark as New
  • Bookmark
  • Subscribe
  • Mute
  • Subscribe to RSS Feed
  • Permalink
  • Print
  • Email to a Friend
  • Report Inappropriate Content

Link copied. Please paste this link to share this article on your social media post.

Posted: ‎2019-12-24 11:14 PM

nice too meet you all sir

Reply

Link copied. Please paste this link to share this article on your social media post.

Anonymous user
Not applicable

Posted: ‎2019-12-30 10:35 PM . Last Modified: ‎2019-12-30 10:36 PM

0 Likes
0
7985
  • Mark as New
  • Bookmark
  • Subscribe
  • Mute
  • Subscribe to RSS Feed
  • Permalink
  • Print
  • Email to a Friend
  • Report Inappropriate Content

Link copied. Please paste this link to share this article on your social media post.

Posted: ‎2019-12-30 10:35 PM . Last Modified: ‎2019-12-30 10:36 PM

Thanks a lot for all your guys sharing, it helpful

------------------------------------------------------------------------

chữa sùi mào gà ở hải phòng

phá thai bằng thuốc ở hải phòng

Reply

Link copied. Please paste this link to share this article on your social media post.

Preview Exit Preview

never-displayed

You must be signed in to add attachments

never-displayed

 
To The Top!

Forums

  • APC UPS Data Center Backup Solutions
  • EcoStruxure IT
  • EcoStruxure Geo SCADA Expert
  • Metering & Power Quality
  • Schneider Electric Wiser

Knowledge Center

Events & webinars

Ideas

Blogs

Get Started

  • Ask the Community
  • Community Guidelines
  • Community User Guide
  • How-To & Best Practice
  • Experts Leaderboard
  • Contact Support
Brand-Logo
Subscribing is a smart move!
You can subscribe to this board after you log in or create your free account.
Forum-Icon

Create your free account or log in to subscribe to the board - and gain access to more than 10,000+ support articles along with insights from experts and peers.

Register today for FREE

Register Now

Already have an account? Login

Terms & Conditions Privacy Notice Change your Cookie Settings © 2025 Schneider Electric

This is a heading

With achievable small steps, users progress and continually feel satisfaction in task accomplishment.

Usetiful Onboarding Checklist remembers the progress of every user, allowing them to take bite-sized journeys and continue where they left.

of