SIST EN 2350:2024
(Main)Aerospace series - Circuit breakers - Technical specification
Aerospace series - Circuit breakers - Technical specification
This document gives design information and specifies test methods for aircraft circuit breakers covered
by European Standards. It is applicable if it is referred to in these standards.
Luft- und Raumfahrt - Schutzschalter - Technische Lieferbedingungen
Dieses Dokument enthält Angaben über die Konstruktion und legt Prüfverfahren für Schutzschalter für Luftfahrzeuge nach Europäischen Normen fest. Es ist anwendbar, wenn in diesen Normen Bezug darauf genommen wird.
Série aérospatiale - Disjoncteurs - Spécification technique
Le présent document donne des informations sur la conception et spécifie les méthodes d’essais des disjoncteurs utilisés à bord d’aéronefs couverts par des normes européennes. Il s’applique chaque fois qu’il est cité en référence dans ces normes.
Aeronavtika - Odklopniki - Tehnična specifikacija
Ta dokument vsebuje projektne informacije in določa preskusne metode za letalske odklopnike, zajete
v evropskih standardih. Uporablja se, če je naveden v teh standardih.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-december-2024
Aeronavtika - Odklopniki - Tehnična specifikacija
Aerospace series - Circuit breakers - Technical specification
Luft- und Raumfahrt - Schutzschalter - Technische Lieferbedingungen
Série aérospatiale - Disjoncteurs - Spécification technique
Ta slovenski standard je istoveten z: EN 2350:2024
ICS:
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 2350
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2024
EUROPÄISCHE NORM
ICS 49.060 Supersedes EN 2350:1990
English Version
Aerospace series - Circuit breakers - Technical
specification
Série aérospatiale - Disjoncteurs - Spécification Luft- und Raumfahrt - Schutzschalter - Technische
technique Lieferbedingungen
This European Standard was approved by CEN on 29 April 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 2350:2024 E
worldwide for CEN national Members.
Contents Page
European foreword . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Design . 6
4.1 Insulating housing . 6
4.2 Trip-free mechanism . 6
4.3 Mounting . 7
4.4 Electrical connection components. 7
4.5 Actuator button . 7
4.6 Calibration safety device . 7
4.7 Leakage paths . 7
4.8 Insulants . 7
4.9 Protection against corrosion . 7
4.10 Fasteners . 7
5 Tests – Requirements – Procedures – Evaluation . 9
5.1 General. 9
5.2 Mechanical tests . 10
5.2.1 Visual inspection . 10
5.2.2 Dimensions and masses . 10
5.2.3 Actuating components . 10
5.2.4 Strength of mounting . 11
5.2.5 Strength of connections . 11
5.3 Environmental tests . 12
5.3.1 Vibration performance . 12
5.3.2 Mechanical shocks . 12
5.3.3 Centrifugal acceleration . 13
5.4 Climatic environmental tests. 14
5.4.1 Sand and dust . 14
5.4.2 Corrosion test (salt spray) . 14
5.4.3 Humidity . 14
5.4.4 Resistance to explosion . 15
5.4.5 Fluid contamination . 15
5.5 Electrical tests . 17
5.5.1 Voltage drop. 17
5.5.2 Insulation resistance . 17
5.5.3 Dielectric strength . 18
5.5.4 Tripping points . 18
5.5.5 Short circuit performance . 19
5.6 Service life tests (endurance) . 22
5.6.1 General. 22
5.6.2 Procedure . 22
5.6.3 Service life with overload tripping . 23
6 Qualification . 23
6.1 General conditions . 23
6.2 Selection of samples . 23
7 Periodic tests to maintain qualification . 26
7.1 Circuit breakers . 26
7.2 Materials . 26
8 Acceptance . 27
8.1 Responsibility . 27
8.2 Tests . 27
8.2.1 General . 27
8.2.2 Evaluation. 27
9 Marking . 28
Bibliography . 29
European foreword
This document (EN 2350:2024) 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 April 2025, and conflicting national standards shall be withdrawn at
the latest by April 2025.
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 2350:1990.
The main changes with respect to the previous edition are as follows:
— EN 2350 (P1), 09/1990 — General editorial improvements and update of Clause 2 and Bibliography.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this document: 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 the United
Kingdom.
1 Scope
This document gives design information and specifies test methods for aircraft circuit breakers covered
by European Standards. It is applicable if it is referred to in these standards.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 2669, Environmental tests for aircraft equipment — Steady-state acceleration
ISO 7137, Aircraft — Environmental conditions and test procedures for airborne equipment
IEC 60050-441, International electrotechnical vocabulary (IEV) — Part 441: Switchgear, controlgear and
fuses
ASTM D740, Standard Specification for Methyl Ethyl Ketone
ASTM D910, Standard Specification for Leaded Aviation — Gasolines
MIL-PRF-7870C, Performance specification, lubricating oil: General purpose, low temperature
MIL-PRF-23699F, Performance specification: Lubricating oil, aircraft turbine engine, synthetic base
NATO code number O-156
MIL-PRF-87937D, Performance specification: Cleaning compound, aerospace equipment
SAE AMS1424G, Deicing/anti-icing fluid, aircraft, Newtonian — SAE Type I
SAE AS1241C, Fire Resistant Phosphate Ester Hydraulic Fluid for Aircraft
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-441 and the
following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp/
— IEC Electropedia: available at https://www.electropedia.org/
Published by American Society for Testing and Materials (ASTM International), available at:
https://www.astm.org/.
Published by Department of Defense (DoD), available at: https://assist.dla.mil/online/start/.
Published by Society of Automotive Engineers (SAE), available at: https://www.sae.org/.
3.1
circuit breaker with “trip-free release”
circuit breaker in which the “open” command takes precedence over the “close” command, i.e when the
electrical trip condition is reached and pressure is exerted on the depressed actuator button, the circuit
is still automatically opened
3.2
pole of a circuit breaker
any main circuit from the input to the pertinent output terminal
Note 1 to entry: The parts of each current path (contacts, sensors, switching parts) are independent and
electrically insulated.
Note 2 to entry: There may be 1, 2 or 3 poles independently of any auxiliary circuits.
3.3
current rating
l
n
current for which the circuit breaker has been designed and designated
Note 1 to entry: Trip characteristics and test values are based on the current rating.
Note 2 to entry: Current is in amperes.
3.4
voltage ratings
voltage levels for which the circuit breaker is designed
Note 1 to entry: Insulation values and test voltages are related to these rated voltages.
Note 2 to entry: Voltage levels are in volts.
3.5
indication of current and voltage values
unless otherwise specified, the AC voltage and AC values shown are RMS values
4 Design
4.1 Insulating housing
In addition to the switching mechanism, the insulating housing shall incorporate the connecting and
mounting systems.
4.2 Trip-free mechanism
The circuit breaker shall be designed to permit trip-free release, i.e. so that it is switched off at overload
and remains switched off even when the button is held in the closed position. Resetting of the circuit
breaker shall be possible only after complete release of the actuator button.
In no case shall operation under these conditions affect the further serviceability of the circuit breaker.
All poles of a multi-pole circuit breaker shall trip on single or multi-phase overload. The time lag
between opening of the first and last pole shall not exceed 10 ms.
4.3 Mounting
All visible parts shall be black and non-reflective.
4.4 Electrical connection components
These shall be suitable to fit the cable lugs (or contacts).
4.5 Actuator button
In the closed position, the visible part of the actuator button shall be black. In the ‟off” (open) position,
a white strip shall be exposed. The outer part of this button shall be insulated from all live parts.
In no case shall the actuator button remain in an intermediate position or give an incorrect indication of
the switching condition of the circuit breaker. It shall not be removable.
— The circuit breaker contacts shall be closed by pushing the actuator button.
— The circuit breaker contacts shall be opened by pulling the actuator button.
The current rating of the circuit breaker shall be indicated indelibly in white colour on the top of the
actuator button. Arrangement of the digits is indicated in the product standard.
4.6 Calibration safety device
The circuit breaker shall be designed in such a way that the calibration cannot be interfered with
without breaking a seal.
4.7 Leakage paths
Leakage paths and the minimum distance to be observed between live parts and all other parts of the
circuit breaker in non-insulating materials and between live parts of opposite polarity shall be sufficient
to avoid damage and spark-over under all operating and ambient conditions.
4.8 Insulants
Insulating parts shall be of non-inflammable or self-extinguishing materials and shall not emit noxious
or explosive vapours.
They shall be resistant to fungus growth and the effects of microorganisms.
Protective coatings and materials which may chip, crack or shatter shall not be used.
4.9 Protection against corrosion
All metal parts shall be either resistant to or protected against corrosion.
In case of contact between dissimilar metals, they shall be protected against electrochemical corrosion.
Where bimetals are used, any corrosion which may occur shall not affect the proper function of the
circuit breaker.
4.10 Fasteners
Screws and nuts shall be locked so that the connections cannot be damaged.
5 Tests – Requirements – Procedures – Evaluation
5.1 General
5.1.1 Unless otherwise indicated, measurement conditions are as follows:
— ambient temperature (23 ± 5) °C;
— pressure 840 hPa to 1 070 hPa;
— relative humidity ≤ 85 %.
5.1.2 Mechanical tests shall be carried out with the circuit breakers mounted in their normal position
on a metal holder at least 2 mm thick.
5.1.3 For thermal tests the circuit breakers shall be mounted with the minimum distance between
each other as specified in the product standard.
5.1.4 For electrical tests the circuit breakers shall be connected to cables as shown in Table 1.
The cables shall be at least 0,5 metre-long.
Where several circuit breakers or the poles of multi-pole circuit breakers are connected in series, the
connecting cable between the circuit breakers or poles shall be 2 m × 0,5 m-long.
The cable lugs used shall be compatible with the circuit breaker terminals.
Table 1 — Cables used for electrical tests for the circuit breakers
a
Current rating Cross section Corresponding AWG
Cross section
A mm
Up to 1 0,6 20
1,5 to 6 1 18
7 to 10 1,2 16
11 to 15 2 14
16 to 20 3 12
21 to 25 5 10
26 to 40 9 8
41 to 50 14 6
a
AWG = American Wire Gauge.
1 hPa = 1 mbar.
5.2 Mechanical tests
5.2.1 Visual inspection
It shall be performed without magnification. It concerns:
— general appearance (surface finish, colour, assembly);
— conformity and quality of markings and inscriptions;
— undamaged condition of calibration seal;
— after climatic environmental tests, inspection of all parts which may show corrosion or poor
legibility of the markings.
5.2.2 Dimensions and masses
These shall conform to the requirements of the product standard and shall be checked using normal
measuring instruments.
5.2.3 Actuating components
5.2.3.1 Actuator button travel
With the circuit breaker in the closed and open positions, the dimensions of the end of the actuating
button in relation to the mounting surface are measured, parallel to its longitudinal axis (direction
of travel).
This measurement is performed three (3) times, with one (1) mechanical switching operation between
each measurement.
The mean values of the measurements recorded shall lie within the tolerances specified in the
product standard.
5.2.3.2 Operating force
The force required to switch ‟onˮ and ‟offˮ shall be measured with a suitable gauge in the line of travel
of the actuator button.
The measurement shall be taken three (3) times in each direction.
The mean value of the measurements shall lie within the limits indicated in the product standard.
5.2.3.3 Strength of actuating components
— Transverse load
The push button in the closed and open positions shall be subjected to the load specified in the
product standard at the end (rim) of the button, perpendicularly to the direction of travel.
The load shall be applied for one (1) minute each in the four (4) main directions.
— Longitudinal load
The push button shall be subjected to the force specified in the product standard, for one (1)
minute each in the push and pull directions.
No damage shall be caused by the loads applied.
— Evaluation
Verification tests: A + E + F + C of Table 5.
5.2.4 Strength of mounting
— Mounting
The tightening torque specified in the product standard shall be applied three (3) times for one (1)
minute each, with one (1) disassembly between each operation.
— Rotation
The circuit breaker housing shall be turned around its mounting in both directions successively at
the torque specified in the product standard.
No deformation outside tolerances or rupture of the locating device shall result. The circuit breaker
housing shall not break.
— Evaluation
Verification tests: A + E + F + C of Table 5.
5.2.5 Strength of connections
— Tightening torque
The connection screws shall be tightened to the torque specified in the product standard.
This torque shall be maintained for one (1) minute. The connection screws shall then be loosened.
This test shall be carried out five (5) times.
No deterioration of the connections shall result.
There shall be no breakage of the circuit breaker housing.
— Strength of connections
Each of the contact lugs (or terminals) shall be subjected to the forces indicated in the product
standard. The forces shall be maintained for one (1) minute and shall not lead to deterioration of
the connections.
The circuit breaker housing shall not break.
— Evaluation
Verification tests: A + C of Table 5.
5.3 Environmental tests
5.3.1 Vibration performance
— Mounting
The circuit breakers shall be mounted on the vibrator. The means of mounting shall be designed so
as to transmit the vibrations over the whole frequency range without absorption or natural
resonance.
The electrical connection shall be made with cables of the sections specified in Table 1.
The connection cables shall be attached on the vibrating support approx. 100 mm from
the terminals.
— Procedure
The circuit breakers shall be subjected to the sinusoidal wave test according to ISO 7137.
The test shall be carried out in three (3) mounting positions along the main axis of the circuit
breaker, at ambient temperature, in the closed and open positions.
The values shall conform to the limits specified in the product standard.
Total vibration time per direction:
o in the closed position: 2 h, circuit breaker load 90 %
...
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