SIST EN 3774-004:2024
(Main)Aerospace series - Circuit breakers, three-pole, temperature compensated, rated currents 1 A to 25 A - Part 004: UNC thread terminals - Product standard
Aerospace series - Circuit breakers, three-pole, temperature compensated, rated currents 1 A to 25 A - Part 004: UNC thread terminals - Product standard
This document specifies the characteristics of three-pole circuit breakers, temperature compensated with a rated current from 1 A to 25 A, used in aircraft on-board circuits at a temperature between −55 °C and 125 °C for ratings ≤ 15 A and −55 °C to 90 °C for ratings > 15 A and at an altitude of 22 000 m max.
These circuit breakers are operated by a push-pull type single pushbutton (actuator), with delayed action “trip-free” tripping.
They will continue to function up to the short-circuit current.
Luft- und Raumfahrt - Schutzschalter, dreipolig, temperaturkompensiert, Nennströme von 1 A bis 25 A - Teil 004: UNC-Klemmengewind - Produktnorm
Dieses Dokument legt die Eigenschaften dreipoliger Schutzschalter fest, temperaturkompensiert, für Nennströme von 1 A bis 25 A, zur Verwendung in Luftfahrzeug-Bordnetzen bei Temperaturen zwischen −55 °C und 125 °C für Nennströme ≤ 15 A und −55 °C bis 90 °C für Nennströme > 15 A und in einer maximalen Höhe von 22 000 m.
Diese Schutzschalter besitzen einen Druckknopf (Betätigungsknopf) mit „Druck-Zug“-Betätigung mit verzögerter Freiauslösung.
Sie sind bis zum Kurzschlussstrom weiterhin funktionsfähig.
Série aérospatiale - Disjoncteurs tripolaires compensés en température, intensités nominales 1 A à 25 A - Partie 004 : Bornes à filetage UNC - Norme de produit
Le présent document spécifie les caractéristiques des disjoncteurs tripolaires compensés en température à intensité nominale de 1 A à 25 A, utilisés dans les circuits embarqués des aéronefs à des températures comprises entre -55 °C et 125 °C pour des intensités ≤ 15 A et de -55 °C à 90 °C pour des intensités > 15 A, à une altitude de 22 000 m max.
Ces disjoncteurs sont commandés par un bouton-poussoir unique (bouton de commande) de type « push-pull », à déclenchement libre temporisé.
Leur fonctionnement est assuré jusqu’au courant de court-circuit.
Aeronavtika - Odklopniki, tripolni, temperaturno kompenzirani, nazivni tok od 1 A do 25 A - 004. del: UNC-navojni priključki - Standard za proizvod
Ta dokument določa značilnosti tripolnih temperaturno kompenziranih odklopnikov z nazivnim tokom od 1 A do 25 A, ki se uporabljajo v letalskih vezjih pri temperaturi med –55 °C in 125 °C za nazivne tokove ≤ 15 A in med −55 °C in 90 °C za nazivne tokove > 15 A ter na največji višini 22.000 m.
Ti odklopniki se upravljajo z enim gumbom (sprožilom) tipa »potisni-povleci« z zakasnjenim proženjem brez sprožila.
Delovali bodo do kratkega stika.
General Information
Relations
Overview
SIST EN 3774-004:2024 is a European standard published by CEN, specifying the product characteristics for three-pole, temperature-compensated circuit breakers rated from 1 A to 25 A. These aerospace-grade circuit breakers are designed primarily for aircraft on-board electrical circuits, operating reliably under extreme environmental conditions including temperatures from −55 °C up to 125 °C (depending on rating) and altitudes up to 22,000 meters.
These circuit breakers feature UNC (Unified National Coarse) thread terminals and utilize a push-pull type single pushbutton actuator with delayed action “trip-free” tripping. They maintain operational integrity even under short-circuit conditions, ensuring the safety and continuity of aircraft electrical systems.
Key Topics
Rated Currents and Operating Conditions
- Rated current between 1 A and 25 A
- Temperature range: −55 °C to 125 °C (for ratings ≤ 15 A), and −55 °C to 90 °C (for ratings > 15 A)
- Operational at altitudes up to 22,000 m
Design and Construction
- Three-pole circuit breakers with UNC thread connection terminals
- Push-pull actuator with delayed trip-free mechanism for reliable disconnection
- Compliance with dimensional and mass specifications ensuring interchangeability
Mechanical and Electrical Characteristics
- Tightening torques specified for attaching nuts (4.75 ± 0.25 N.m) and connection hardware (1.6 ± 0.1 N.m)
- Resistance to vibrations, shocks, corrosion, humidity, and contaminating liquids per aerodynamic operating environments
- Endurance tests for no-load (up to 5,000 operations) and load conditions (2,500 operations)
- Guaranteed voltage drop and maximum tripping thresholds specified by rated currents
- Dielectric rigidity and insulation resistance ensuring electrical safety
Environmental Compatibility
- Suitability for severe aerospace environmental stresses including temperature extremes, humidity, altitude, and lightning-induced overvoltage
Marking and Identification
- Clear marking of rated current and product coding on actuators according to the specified rated current code
Applications
SIST EN 3774-004:2024 circuit breakers are critical components in aerospace electrical systems, offering:
Aircraft On-Board Electrical Protection
Designed for three-phase circuits in commercial and military aircraft to protect wiring and equipment from faults and overloads, enhancing flight safety.High-Altitude and Harsh Environment Usage
Suitable for aircraft operating at high altitudes and extreme temperatures, ensuring reliable circuit interruption under challenging conditions.Integration in Aerospace Electrical Panels
Built to fit standardized panel cuts and mounting as per aerospace equipment specifications, facilitating straightforward installation and replacement.Flight Control and Power Distribution Systems
Used in essential flight systems, avionics power distribution, and onboard electrical subsystems requiring dependable circuit protection.
Related Standards
To ensure full compliance and interoperability within aerospace electrical systems, SIST EN 3774-004:2024 references and aligns with the following related standards:
- EN 3774-001:2014 - Aerospace series circuit breakers, three-pole, temperature compensated - Technical specifications
- EN 2350 - Aerospace series - Circuit breakers - Technical specification
- EN 3841-305 - Aerospace series - Circuit breakers - Test methods including short-circuit performance
- EN 6113 - Aerospace series - Circuit breaker connecting and attachment hardware
- TR 6083 - Aerospace series - Cut-outs for installation of electrical components
- SAE AMS-STD-595 - Standardized colors used in government aerospace procurement
SIST EN 3774-004:2024 serves as an essential standard for manufacturers, engineers, and maintenance professionals involved in aerospace electrical systems, providing clear, rigorous requirements for reliable three-pole circuit breakers with UNC thread terminals designed to withstand the demanding conditions of modern aviation. This standard reinforces safety, quality, and interoperability in critical aircraft power distribution systems.
Standards Content (Sample)
SLOVENSKI STANDARD
01-julij-2024
Aeronavtika - Odklopniki, tripolni, temperaturno kompenzirani, nazivni tok od 1 A
do 25 A - 004. del: UNC-navojni priključki - Standard za proizvod
Aerospace series - Circuit breakers, three-pole, temperature compensated, rated
currents 1 A to 25 A - Part 004: UNC thread terminals - Product standard
Luft- und Raumfahrt - Schutzschalter, dreipolig, temperaturkompensiert, Nennströme
von 1 A bis 25 A - Teil 004: UNC-Klemmengewind - Produktnorm
Série aérospatiale - Disjoncteurs tripolaires compensés en température, intensités
nominales 1 A à 25 A - Partie 004 : Bornes à filetage UNC - Norme de produit
Ta slovenski standard je istoveten z: EN 3774-004:2024
ICS:
29.120.50 Varovalke in druga Fuses and other overcurrent
nadtokovna zaščita protection devices
49.060 Letalska in vesoljska Aerospace electric
električna oprema in sistemi equipment and systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN 3774-004
EUROPEAN STANDARD
NORME EUROPÉENNE
April 2024
EUROPÄISCHE NORM
ICS 49.060 Supersedes EN 3774-004:2014
English Version
Aerospace series - Circuit breakers, three-pole,
temperature compensated, rated currents 1 A to 25 A -
Part 004: UNC thread terminals - Product standard
Série aérospatiale - Disjoncteurs tripolaires compensés Luft- und Raumfahrt - Schutzschalter, dreipolig,
en température, intensités nominales 1 A à 25 A - temperaturkompensiert, Nennströme von 1 A bis 25 A
Partie 004 : Bornes à filetage UNC - Norme de produit - Teil 004: UNC-Klemmengewinde - Produktnorm
This European Standard was approved by CEN on 5 February 2024.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2024 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 3774-004:2024 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 4
4 Dimensions and mass . 5
4.1 Dimensional characteristics . 5
4.2 Electrical diagram . 6
4.3 Mass . 6
4.4 Panel mounting . 6
5 Characteristics . 7
5.1 Material, surface treatment . 7
5.2 Mechanical characteristics . 7
5.2.1 Fasteners . 7
5.2.2 Recommended tightening torque of attaching nut for installation . 7
5.2.3 Recommended tightening torque of connection hardware for installation . 7
5.2.4 Resistance to vibrations . 7
5.2.5 Resistance to shocks . 7
5.2.6 Mechanical endurance . 7
5.3 Environment characteristics . 7
5.3.1 Humidity . 7
5.3.2 Corrosion . 7
5.3.3 Contaminating liquids . 7
5.3.4 Overvoltage caused by lightning . 8
5.4 Electrical characteristics . 8
5.4.1 Nominal voltage of operational circuits . 8
5.4.2 Voltage drop at Ι and low current . 8
n
5.4.3 Minimum and maximum tripping thresholds . 8
5.4.4 Overload trip . 9
5.4.5 Short-circuit values . 9
5.4.6 No-load and load endurance . 10
5.4.7 Dielectric rigidity . 10
5.4.8 Insulation resistance . 10
6 Designation . 11
7 Rated current code . 11
8 Delivery codes . 11
9 Marking . 12
10 Technical specification . 12
European foreword
This document (EN 3774-004:2024) has been prepared by ASD-STAN.
After enquiries and votes carried out in accordance with the rules of this Association, this document has
received the approval of the National Associations and the Official Services of the member countries of
ASD-STAN, prior to its presentation to CEN.
This document shall be given the status of a national standard, either by publication of an identical text
or by endorsement, at the latest by October 2024, and conflicting national standards shall be withdrawn
at the latest by October 2024.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 3774-004:2014.
The main changes with respect to the previous edition are as follows:
— EN 3774-004 (P2), 07/2014 — A typo error in Table 7: as it is a circuit breaker wit
...
Frequently Asked Questions
SIST EN 3774-004:2024 is a standard published by the Slovenian Institute for Standardization (SIST). Its full title is "Aerospace series - Circuit breakers, three-pole, temperature compensated, rated currents 1 A to 25 A - Part 004: UNC thread terminals - Product standard". This standard covers: This document specifies the characteristics of three-pole circuit breakers, temperature compensated with a rated current from 1 A to 25 A, used in aircraft on-board circuits at a temperature between −55 °C and 125 °C for ratings ≤ 15 A and −55 °C to 90 °C for ratings > 15 A and at an altitude of 22 000 m max. These circuit breakers are operated by a push-pull type single pushbutton (actuator), with delayed action “trip-free” tripping. They will continue to function up to the short-circuit current.
This document specifies the characteristics of three-pole circuit breakers, temperature compensated with a rated current from 1 A to 25 A, used in aircraft on-board circuits at a temperature between −55 °C and 125 °C for ratings ≤ 15 A and −55 °C to 90 °C for ratings > 15 A and at an altitude of 22 000 m max. These circuit breakers are operated by a push-pull type single pushbutton (actuator), with delayed action “trip-free” tripping. They will continue to function up to the short-circuit current.
SIST EN 3774-004:2024 is classified under the following ICS (International Classification for Standards) categories: 29.120.50 - Fuses and other overcurrent protection devices; 49.060 - Aerospace electric equipment and systems. The ICS classification helps identify the subject area and facilitates finding related standards.
SIST EN 3774-004:2024 has the following relationships with other standards: It is inter standard links to SIST EN 3774-004:2014. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
You can purchase SIST EN 3774-004:2024 directly from iTeh Standards. The document is available in PDF format and is delivered instantly after payment. Add the standard to your cart and complete the secure checkout process. iTeh Standards is an authorized distributor of SIST standards.
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