IEC TR 61912-2:2009 PDF

Name: IEC TR 61912-2:2009 — Low-voltage switchgear and controlgear - Over-current protective devices - Part 2: Selectivity under over-current conditions
SKU: IEC TR 61912-2:2009
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Low-voltage switchgear and controlgear - Over-current protective devices - Part 2: Selectivity under over-current conditions

Название (английский):

IEC TR 61912-2:2009

Low-voltage switchgear and controlgear - Over-current protective devices - Part 2: Selectivity under over-current conditions

Статус документа:: Действующий
Формат:: Электронный (PDF)
Количество страниц:: 33
Дата публикации:: 13 мая 2009 г.
Издание:: IEC TR 61912 edition 1 version 1
ICS:: 29.130.20

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Описание (английский):

IEC 61912-2:2009(E), which serves as an application guide for the determination of selectivity between over-current protective devices of low-voltage switchgear and controlgear, summarises the definitions of the terminology and provides examples of application.

Abstract

Похожие стандарты

Стандарты, упомянутые в описании

Overview - IEC TR 61912-2:2009 (Selectivity under over-current conditions)

IEC TR 61912-2:2009 is an IEC Technical Report and application guide addressing selectivity (coordination) between over‑current protective devices in low‑voltage switchgear and controlgear. The report summarizes terminology, presents methods to determine selectivity between devices in series, and provides worked examples to help designers optimize supply availability while meeting protection objectives. It complements device standards by focusing on practical coordination of circuit‑breakers, fuses, motor overload relays, RCDs and related equipment.

Key topics and technical content

Definitions and terms: consolidated glossary and abbreviated terms for consistent use of “selectivity”, “upstream/downstream” devices, fault zones, etc.

Selectivity determination methods: guidance for assessing selectivity for different device pairings, including:

circuit‑breaker / circuit‑breaker
circuit‑breaker / fuse and fuse / circuit‑breaker
fuse / fuse
circuit‑breaker / motor overload relay (MOR)
circuit‑breaker / CPS (connector protective system) and fuse / CPS

RCD selectivity: principles for selectivity between residual current devices (earth‑leakage and earth‑fault conditions) including time‑delay (Type S) considerations.

Zone Selective Interlocking (ZSI): operating principles and examples for using ZSI to improve selectivity in multi‑supply systems.

Over‑current protection relays (OCRs): single‑input energizing quantity relays with dependent/independent timing and their coordination considerations.

Worked examples and annexes: practical time‑current curve examples, grades of selectivity, and discussion of standing loads affecting overload-zone selectivity.

Practical applications

Design and verification of LV distribution and motor protection schemes to ensure selective disconnection of faults and maximum continuity of supply.

Choosing and coordinating protective devices to avoid unnecessary upstream trips and reduce outage scope for critical loads.

Applying ZSI and OCR strategies where conventional time/current discrimination is limited by fault level or protection device characteristics.

Economic optimization: using limited or graded selectivity where full selectivity across the entire prospective fault current is unnecessary or impractical.

Who should use this standard

Electrical design engineers and system integrators working on low‑voltage power distribution

Protection and relay engineers specifying coordination studies

Installers, testing and commissioning teams validating selective protection

Specification writers and procurement specialists evaluating device combinations

Related standards (referenced)

IEC 60269 series (fuses), IEC 60947 series (circuit‑breakers, contactors), IEC 60898-1, IEC 61008-1, IEC 61009-1, and relevant IEC 60255 relay standards - all cited as normative references for device characteristics and testing.

Keywords: IEC TR 61912-2:2009, selectivity, over‑current protective devices, low‑voltage switchgear, coordination, circuit‑breaker, fuse, RCD, ZSI.

IEC TR 61912-2:2009 PDF

Abstract

Похожие стандарты

Overview - IEC TR 61912-2:2009 (Selectivity under over-current conditions)

Key topics and technical content

Practical applications

Who should use this standard

Related standards (referenced)

Технические детали

IEC 60269-6:2010/COR1:2010

Corrigendum 1 - Low-voltage fuses - Part 6: Supplementary requirements for fuse-links for the protection of s…

IEC 60947-5-1:2016/COR2:2020

Corrigendum 2 - Low-voltage switchgear and controlgear - Part 5-1: Control circuit devices and switching elem…

IEC 60898-1:2015/COR1:2015

Corrigendum 1 - Electrical accessories - Circuit-breakers for overcurrent protection for household and simila…

IEC 61008-1:2024

Residual current operated circuit-breakers without integral overcurrent protection for household and similar…

IEC 61009-1:2024

Residual current operated circuit-breakers with integral overcurrent protection for household and similar use…

BS EN IEC 60255-181:2019

Measuring relays and protection equipment - Functional requirements for frequency protection