1、AECMA STANDARD NORME AECMA AECMA NORM Edition approved for publication 14 March 2003 prEN 3841-404 Edition P 3 March 2003 Comments should be sent within six months after the date of publication to Electrical Domain AECMA-STAN ICs: 49.060 Descriptors: ENGLISH VERSION Supersedes edition P 2 September
2、1998 Aerospace series Circuit breakers Test methods Part 404: Explosion proofness Srie arospatiale Disjoncteurs Mthodes dessais Partie 404 : Antidflagration Luft- und Raumfahrt Schutzschalter Prfverfahren Teil 404: Explosionsdichtheit This “Aerospace Series“ Prestandard has been drawn up under the r
3、esponsibility of AECMA-STAN (The European Association of Aerospace Industries - Standardization). It is published on green paper for the needs of the European Aerospace Industry. It has been technically approved by the experts of the concerned Domain following member comments. Subsequent to the publ
4、ication of this Prestandard, the technical content shall not be changed to an extent that interchangeability is affected, physically or functionally, without re-identification of the standard. After examination and review by users and formal agreement of AECMA-STAN it will be submitted as a draft Eu
5、ropean Standard to CEN (European Committee for Standardization) for formal vote. I I Copyright 2003 O by AECMA-STA1 Page 2 prEN 3841-404: 2003 Foreword This standard was reviewed by the Domain Technical Coordinator of AECMA-STANS Electrical Domain. After inquiries and votes carried out in accordance
6、 with the rules of AECMA-STAN defined in AECMA- STANS General Process Manual, this standard has received approval for Publication. Page 3 prEN 3841-404: 2003 1 Scope This standard specifies a method of verifying explosion proofness of circuit breakers. It shall be used together with EN 3841-100. 2 N
7、ormative references This European Standard incorporates by dated or undated reference provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions
8、of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. IS0 7137, EN 3841-100, Aircraft - Environmental conditions and test procedures for airborne equipment)
9、 Aerospace series - Circuit breakers - Test methods - Patt 700: General 2) 3 Method 3.1 Test mounting 3.1 .I General The circuit breakers shall be mounted approximately in the centre of the chamber, and as specified in EN 3841-100, in connection with the applicable product standard. The chamber volu
10、me (2 25 i) shall ensure that the circuit breakers are evenly exposed to the explosive mixture. The test chamber shall be fitted with a spark plug which allows the combustibility of the mixture to be verified when the chamber is closed. The test chamber shall provide a facility to switch on the circ
11、uit breakers when the chamber is closed (for manual or remote operation). 3.1.2 Test circuit According to figure 1 with d.c. and a.c., single-pole. According to figure 2 with a.c., three-pole. 1) Endorsement of EUROCAEIED-14C and RTCNDO-160C 2) Published as AECMA Prestandard at the date of publicati
12、on of this standard Page 4 prEN 3841-404: 2003 r e! G S m 2 c“ . e Y- N S m e! G 2 c“ . e Y- Page 5 prEN 3841-404: 2003 3.1.3 Test mixture Gas mixture of air and fuel vapour (grade of fuel 100/130 octane gasoline or propane or standard hexane, with a volumetric ratio of 13:l) following IS0 7137. 3.1
13、.4 Test temperature The test temperature shall be 70 “C. 3.1.5 The pressure in the test chamber shall be atmospheric pressure at normal altitude. Pressure in the test chamber 3.2 Procedure The test chamber shall be heated to the temperature and filled with the explosive mixture. (the explosive mixtu
14、re may also be produced by injecting the fuel quantity proportionate to the chamber volume, provided that an adequate mixing and even distribution of the mixture are ensured). The circuit breakers shall be stored in the explosive atmosphere for 3 h prior to break operations. The operations as outlin
15、ed in the product standard shall be carried out at intervals of 1 h. The mixture shall remain explosive during this period. 3.3 Requirement The explosive mixture shall not ignite when the circuit breakers are operated. On completion of the operations, combustibility of the mixture shall be verified by means of the spark plug. If the mixture does not ignite, the test shall be repeated with new test samples.
