1、MIL-T-3720 59 W 9797906 OOOL25 7 I 27 Sepcembe; 1968 Sv PSRSEDING SGMES PD-L!+8A 3i March i967 MILITARY SPECIFICATION TFtANSF0RME;RS AND INDUCTORS, NON4XPLOSIVE , CrENERAL SPECIFICATION FOR 1.0 scorn 1.1 Scope. This specification contains the general requirements for non- explosive transformers of o
2、pen coil and core construction intended for use in svaled electronic air-environment enclosures. 2.0 APPLICABJE DOCUMENTS 2.1 tion for bids or request for proposal form a part of %his specification to the extent specified. The following documents of thg issue in effect on date of invita- SPECIFICATI
3、ONS Mili targ MIL-T -27 MIL-P- STANDARDS Federal Fed STD-595 Militam MILS TD -12 9 MI L-S TD -13 OC Transformers and Inductors (Audio power, and liigh power pulse General Specification for) Preservation, Methods of Paint, Requirements Marking for shipment l). 3.9 Induced Voltage. When transforners a
4、nd inductors are tested as specified in MIL-T-27, there shall be no evidence of continuous arcing, breakdown of insulation, or any abrupt changes in input current (see 4.1). 3.10 InsulLstion Besistance . When transfomers and inductors are masured as specified in MIL-T-27, the minimura insulation res
5、istance shall be 7500 megohms (see 4. i). 3.11 Winding Continuity. Whm .transforinsrs and 5nductors are tested as specified in LXIL-I-27, all windings shall be electrically continuous (see 4.1). 3.12 Electrical Characteristics. When transforiners md inductors are kested as specified in MiL-1-27, the
6、 applica3le electrical characteristics shall be as specified, including tolerances (see 3.1 and lk.1). 3 .i3 Temperature Rise. specified in IIILdT-27, the temperature rise of any winding above the specified x&um ambient temperature (see 3.1) shall not exceed the valus specified (see 3 .i) .and there
7、 shall be no evidence of physical damage (see 4.1). When 5ransformei-s and inductors are tested as , “I Licensed by Information Handling Services- .- MIL-T-3720 59 a 9999906 0080329 4 W MIL-T-yFL)( USAF 1 3.l4 Thermal Shock. W.sn transfomers and inductors are tested as specified in MIL-1-27, not mor
8、e than 10 percent of the surface shall have peeling, flaking, chipsing, cracking, crazing, or other impairinsnt of the protective coating (see 4. i). 3.15 Vibration. When trmsforrners and inductors are tested as specified in LyIL-T-27, not more than 10 percent of the surface shall have peeling, flak
9、ing, chipping, cracking, crazing, or other hpimnzn: of the protective coating (see 4.1). 3.16 Shock. NIL-T-27, not illme than 10 percent of the surface shall have peeling, flaking, chipping, cracking, crazing, or other impairmsnt of the protective coating (see &.i). When transformers and inductors a
10、re tested as specified in 3.17 Qverload. When transforinera and inductors are tested as specified in MIL-I?-27, not mm-e than 10 percent of the surface shall have peeling, flaking, chipsing, cracking, crazing, or othher impairinent of the protective coating (see 4. I). 3.18 - Life. NIL-T-27, there s
11、hall be no evidence of physical or electrical damage (see 4.1). When transfomsrs and inductors are tested as specified in 3.19 Resistance to Soldering Heat. When transformrs and inductors are tested as specified in MIL-I?-27, there shall be no softening of the insulation or loosening of windings or
12、terminals (see 4.1). 3.20 Marking. Transfomers and inductors shall be marked in accordance with MIL-STD-130. transformer or inductor and each terminal shall be idsntified by the applicable nimber specified in the detail specification. The manufacturers part nunber shall be stamped on the 3.20.1 Symb
13、ol. Transformers arnd inductors supplied per this specification shall be identified by the symbol illustrated in Figure 1. The color shall be red 11105 per Fed. STD 595. 3.21 Workinanship. Transfomers and inductors shall be processed in such a manner as to be uniform in quality and shall be free fro
14、m defects that will affect life or serviceability. 4.0 QUAUTY ASSURAN PROVISIONS 4.1 Walitg Assurance. The quality assurance provisions of MILdT-27 ap?ly as requirenents of this specification unless otherwise specified. 5 Licensed by Information Handling Services- MIL-T-3720 57 W 7797706 OOOl130 O W
15、 MIL-T-83720( US Al! ) Outline dimensions of the marking synbol to be of bine relative proportims indicated below. 2 Numbers are absolute FIGURE I Marking Symbol ( see para 3.20 _- _. -.y- 6 Licensed by Information Handling Services- MIL-T-83720 57 W 7177706 0080131 2 MIL-T -83720 (US AF ) 4.1.1 Res
16、ponsibility for Inspection. Unless otherwise specified in the conbract or pnchase order, the supplier is responsible for the performance of all inspection requirenients as specified herein. Except as otherwise specified, the sup2lier may utilize his o-i facilities or any cormercial laboratory accept
17、able to the Goverment. examination axl tests shall be kep,t complete and available to the Govern- ment as specified in the contract or order. The Goverment reserves the right to perform any of the inspections set forth in the specification where such inspsctions are dsemed necessary to assure suppli
18、es and services confom to prescribed requirements. 4.1.1.1 Test equipmnt and inspection facilities. Test equipment and inspection facilities shall be of sufficient accuracy, quality, and qxmtity to pelirfit perforniance of the required inspection. The supplier shall establish calibration 3f inspecti
19、on eqxiprnent to the satisfaction of the Government. Inspection records of the 4.2 Classification of Inspections. The examination and testing of transformers and inductors shall be classified as follows: a. Preprxhction Inspection b. Acceptance Inspection 4.3 Preproduction Inspection. Preproduction
20、inspection will be per- formed by the supplier after award ai? contract and prior to pyod-Action at a location acceptable to the Government. The tests to be perforinsd shall consist of the tests listed in Table I. accordance with MIL-T-27, unless otherwise specified. The tests shall be performed in
21、4.3.1 Material Decompsition. Sup2liez-s furnishing transforniers and inductors per this specification shall furnish dakailed %ata sho-ng quantitatively the gases of decoinposition of the materials of the transfomer or inductor at temperatures froin 100C through 50C. data shall be sufficient to prove
22、 to the satisfaction of the Govern- ment that the materials of decomposition are non-eqlosive and cannot combins to form an explosive mi-xbure (see 6.2). The 7 Licensed by Information Handling ServicesMIL-T-3720 57 m 777770b OOOL32 4 m _ - - MIL-T-83720( USAF ) TABE3 I PFEPRODUCTIOX TESTS Test Metho
23、d Grmp I (All sample units) Reauirement Para Visual & Mechanical Inspection (External) 3.1, 3.4, 3.4. 1 4- 1 Die lec tric Withstanding Voltage 3 .e 4.1 Barometric Pressure (When applicable) 3.8.1 4.1 Ind-xed Voltage (When specified) 3.9 4.1 Electrical Characteristics 3-12 4-1 Corona Discharge (When
24、specified) 3.7 4.1 Insulation Re si stance9 3.10 4.1 3.4.4, 3.5, and 3.21 Group II (2 ea units2 Temperature Rise (i sample) Thew1 Shock Vibration Shock (Winding Continuity) Dielsctric withstanding voltags (9% of initial) Induced Vo It age Winding Continuity Overload Dielectric withstanciing voltage
25、Induced voltage Insulation Resistance Winding Continuity Group III (2 ea units) Life Dielectric withstanding voltage (90$ of initial) Insulation Resistance Induced Voltage Visuai & Mechanical (external) Grmg IV 3.13 3*u 3.11 3.15 3.16 3.18 4. 1 Explosion Test (i ea unit) 3.6 4.5.1.1 Visual Examinati
26、on (internal & external) 3.1, 3.4,3.4.1 . 4.1 3.4.2, 3.4.3, 3.4k 3.5, 3.3, and 3.2.1 . .- - . - 8 I Licensed by Information Handling ServicesI MI L-T -83720( US AF ) 4.3.2 Samples - Five samples shall be subjected to the test in Table 1, The nuaber of samples to be used in each test grou? shall be a
27、s indicated, 4.3.3 will be cause for refusal to authorize production, Failure - Failure in any of the applicable examinations or tests 4.3.4 Disposition of Samples - Samples subaitted to preproduction tests shall not be delivered as part of the contract quantity. 4.4 Acceptance Inspection 4.4.1 Insp
28、ectiori Groups. Inspection of product for delivery shall consist of Group A, B, and C. 4.4.1.1 Group A and B. except that performance of sealing test is not required. Group A and B inspection shall be per MIL-T-27, 4.4.1.2 Group C. per 3.6 and 4.5.1.1 of this specification. be classified as a failur
29、e if any or all requirements of paragraph 3.6 are not satisfied. 4.4,.1.3 selected froin each months produstion except that, if x3re than three part numbers are being produced concurrently, n3 more than one sample each to a maximu? of six types need -De subjected to this test in any given month. 4.4
30、.1.4 Disposition of Sample Units - Sam?le units which have been subjected to explosion testing shall be foriuarded to the contracting office, but shall not be considered as part of the contract order qantity. 4.4.1.5 production shall be imiediately held up and one of the following actions taken as a
31、pplicable : Group C inspection shall consist of the explosion test A transformer or inductor shall Sampling Plan - Two sample udts of each part iiunoer shall be Non-Comphnce - If any sample fails to pass Group B inspection, (a) One part number in prodxtion. Two additional sam2le units If a failure s
32、hall be selected and subjected to the explosion test. occurs, all units in the lot shall be scrappsd. shall be notified, and failure determined and corrective action taken. Upon approval by he Government, of the failure report and corrective action proposal, production may be resumed. If no failure
33、occurs, the lot may be shipped. The contracting officer (b) More than:one part number in production. Two additional sample units of each part number shall be selected and subjected to the explosion test. Licensed by Information Handling ServicesMIL-T-83720 57 W 9777706 008013Lt 8 I MI L-T -83 720( U
34、3 AF ) (i) If a failure re-occurs only on a unit or mits of ths same part number (s) which failed initially, the lot of this particular design shall be scrapped, the cause of failure determined and corrective action taken. and corrective action proposal, production may be resuilivd. Upon approval by
35、 the Government, of the failure report (2) If the saaples of any particular part number (s) pass both test and re-test, the lot of this particular design (s) shall be shipped. 4.4.2 shall be selected and inspected in accordance with specification MIL-P- to verify conformance with requirements in Sec
36、tion 5 of this specification. Inspection cf Praparation for Delivery Sample - Items and packs 4.5 Nethods of Examination and Tests 4.5.1 Examinztion and Tests - ikamination and Tests shall be performed using methods in accordance with MIL-T-27, unless other.wise spmified. The exaininations and tests
37、 to be perfomsd shall correspond with the requirements of this spacification, MIL-T-27 and the applicable detall drawing or specification. 4.5.1.1 Explosion test. 4.5.1.1.1 Equipmsnt - The basic equipment shall be as shown in Figure 2. 4.5.1.1.2 Explosion Chambers - The outeer chanbar shall be capab
38、le of protecting test psrsonnel from inj-dry should an eqlosion occur. shall be a provision for observing Lhe inner chambsr &.iring Lhe entire test period. The volume of the inner explosion chmber shall be equal to the volurne of the free air space of the equipment in rqhich the transformers and/or
39、inductors will be used. (See note 6.3). The chamber shall be cubical in shape and shall be formed of a material that does not outgas. A press fit cover shall be designed such that, a pull of i5 lbs minimum shall be required to displace it. feed throughs for DZ power to be applied to the windings of
40、the test transformer and an arcing rod by which an arc can be podxed in the chamber. The insulation material shall be non-explosive . There The chmber shall be airtight when the cover is fitted into place. Provisions shall be made for insulated 4.5.1.1.3 a Dc current to the transformer windings such
41、 that the temgerature of Power suprlx - The Po-r supply shall be capable of supplying the transformer windings may be increaied at a controlled iate up to 50C. 4.5.1.1.4 Resistance Bridge - The resistance bridge shall be an instm- ment capable of measuring the transformer winding resistance accurate
42、ly &thin 2 1%. I 10 Licensed by Information Handling Services MIL-T-83720 57 W 7777706 0080335 T I MIL -T -83 72 O ( US AF ) I- O z O I- a a - a I a W W o cn ZW m ! cnm 29 O W i L O 11 I P O a a W m I a I o z cn O J Q X w A A H v) 0 a W a I o z O cn 3 o a x w w I- 3 O Q 1 a, tn to a, I t t t C 0 n O
43、 a .- - x W (u W a Licensed by Information Handling ServicesMI L-T -83 720 (US AF ) 4.5.1.1.5 connect the transformsr -inding .to either the DC poxer supply or the re- sistance bridge. Switch - A doable pole single throw switch shall bz used to 4.5.1.1.6 -High Voltage Probe - Tesla Coil, Arthur H. T
44、hmas Co., Philadelphia 5, Pa., Catalog No. 1060 or a governmsnt approved equivalent. 4.5.1.1.7 the greatest resistance shall be connected to the DsC power su-ply as illustrated in Figure 1. A resistance vs temperarture grxph shall be mads for the winding of the test transformer or inductor to which
45、D: voltage is to be apslied. Test Method - Unless otherwise specified, the “inding having The graph shall be computed from the formula 234.5 + T2 wheye (R1) is the resistance of the winding of the - R2 - R1 234.5 + Ti test transfo-mer at a knvm tenperature (T ). values of temperature in the range 10
46、0C -16000C. R2 is the resistance of the test winding at T2. Using the pap5 while using the test set- up in Figure 2, the teqerature of the transfomer can be deterinined. After h3ok-up and before placing the cover on the inner eqlosion chamber, the position of the arcing rod should be adjusted so tha
47、t an arc occurs in the chamber when the high voltage probe is asplied to the external connection of the arcing rod. The cover of the inner cham3er shall be secured. or gas except air. The outer chamber shzll be secured. Power shall be applied to the test winding such that the average rate of teapera
48、ture rise shall not exceed 300% per hour n3r be less than 200% per how. When the test winding reaches a temperature of 400C an arc shall be generated within the chamber. through the observation port of the outer chamber when the arc occurs. An arc shall be gensrated at 50C intervals until a minhum t
49、eiqprature of 590% is reached or an explosion occurs. The arc shall be applied for 5 s8c minimum. Upon coinpletion of the test, the cover of the inner chamber shall be carefully removed, the chamber ventilated and an arc generated to vayify that arcing occurred during the test T2 represeats acscuwd Ths chamber shall contain n3 other liquid The inner chamber should be observed 5.0 PFEPARATION FOX DELIVERY 5.1 Preservation and Packaging. 5.1.1 Level4. Transformsrs and inductors shall be individually pro- tected and unit pack
