1、Comments, suggestions, or questions on this document should be addressed to: Defense Supply Center, Columbus, ATTN: DSCC VAT, Post Office Box 3990, Columbus, Ohio 43218-3990 or by email Resistordla.mil. Since contact information can change, you may want to verify the currency of this address informa
2、tion using the ASSIST Online database at https:/assist.daps.dla.mil/ AMSC N/A FSC 5905 INCH-POUND MIL-PRF-29C 5 February 2010 SUPERSEDING MIL-PRF-29B 30 November 1998 PERFORMANCE SPECIFICATION RESISTORS, FIXED, METER MULTIPLIER, EXTERNAL (HIGH VOLTAGE, FERRULE TERMINAL TYPE) This specification is ap
3、proved by all Departments and Agencies of the Department of Defense. 1. SCOPE 1.1 Scope. This specification covers the requirements for high-voltage, external, meter-multiplier, fixed resistors of the ferrule-terminal type for use with direct-current (dc) instruments drawing 1 milliampere at full-sc
4、ale deflection. Designers are CAUTIONED on using these resistors in pulse applications (see 6.5). 1.2 Classification. 1.2.1 Part or Identifying Number (PIN). The PIN must be in the following form and as specified (see 3.1). MFC 504 Style (1.2.1.1) Resistance (1.2.1.2) 1.2.1.1 Style. The style is ide
5、ntified by a three-letter symbol. The first two letters, MF, identify high voltage, external, meter-multiplier, fixed resistors of the ferrule-terminal type. The third letter identifies the particular physical dimensions. 1.2.1.2 Resistance. The nominal resistance in ohms is designated by a three-di
6、git number. The first two digits represent the first two significant figures of the figures of the resistance value, the third digit indicates the number of zeros to follow. 1.2.1.2.1 Resistance range. Resistors have a resistance range of 0.5 ohm to 20 megohms. 1.2.1.2.2 Nominal resistance and rated
7、 voltage. Nominal resistance and rated voltages are as specified in table I. TABLE I. Nominal resistance and rated voltage. Type designation Nominal resistance in megohms Rated voltage in kilovolts Type designation Nominal resistance in megohms Rated voltage in kilovolts MFC504 0.5 0.5 MFB355 3.5 3.
8、5 MFC804 0.8 0.8 MFA355 3.5 3.5 MFC105 1.0 1.0 MFA405 4.0 4.0 MFB105 1.0 1.0 MFA505 5.0 5.0 MFB155 1.5 1.5 MFA605 6.0 6.0 MFB205 2.0 2.0 MFD106 10.0 10.0 MFB255 2.5 2.5 MFE156 15.0 15.0 MFB305 3.0 3.0 MFF206 20.0 20.0 Provided by IHSNot for ResaleNo reproduction or networking permitted without licen
9、se from IHS-,-,-MIL-PRF-29C 2 2. APPLICABLE DOCUMENTS 2.1 General. The documents listed in this section are specified in sections 3 and 4 of this specification. This section does not include documents cited in other sections of this specification or recommended for additional information or as examp
10、les. While every effort has been made to ensure the completeness of this list, document users are cautioned that they must meet all specified requirements documents cited in sections 3 and 4 of this specification, whether or not they are listed. 2.2 Government documents. 2.2.1 Specifications, standa
11、rds, and handbooks. The following specifications, standards, and handbooks form a part of this document to the extent specified herein. Unless otherwise specified, the issues of these documents are those cited in the solicitation or contract (see 6.2). DEPARTMENT OF DEFENSE STANDARDS MIL-STD-202 - T
12、est Methods Standard Electronics and Electrical Components Parts. MIL-STD-1285 - Marking of Electrical and Electronic Parts. (Copies of these documents are available online at https:/assist.daps.dla.mil/quicksearch/ or from the Standardization Document Order Desk, 700 Robbins Avenue, Building 4D, Ph
13、iladelphia, PA 19111-5094). 2.3 Order of precedence. Unless otherwise noted herein or in the contract, in the event of a conflict between the text of this document and the references cited herein (except for related specification sheets), the text of this document takes precedence unless otherwise n
14、oted. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained. 3. REQUIREMENTS 3.1 Requirements for individual resistor types. Requirements or exceptions applicable to individual resistor types are specified on FIGURE 1 (see 6.2). 3
15、.2 Qualification. Resistors furnished under this specification shall be products that are authorized by the qualifying activity for listing on the applicable qualified products list (QPL) before contract award (see 4.4 and 6.3). 3.3 Materials. Materials shall be used which will enable the resistors
16、to meet the performance requirements of this specification. Acceptance or approval of any constituent material shall not be construed as a guaranty of the acceptance of the finished product. 3.3.1 Fume-emitting material. Material that emits deleterious or toxic fumes at a temperature of 110OC or low
17、er shall not be used. 3.3.2 Ferrous material. Ferrous material shall not be used for current-carrying parts. 3.3.3 Pure tin. The use of pure tin, as an underplate or final finish is prohibited both internally and externally. Tin content of resistor components and solder shall not exceed 97 percent,
18、by mass. Tin shall be alloyed with a minimum of 3 percent lead, by mass (see 6.4). 3.4 Interface and physical dimension requirements. Resistors shall meet the interface and physical dimensions specified herein. Resistors shall consist of a resistance element or series of elements of the wirewound or
19、 film type. 3.4.1 Protective coating or enclosure. The resistor assemblies shall be protected by a coating or enclosure of insulating and moisture-resistant material which shall completely cover the exterior of the resistance element, including connections between any two elements or between any ele
20、ment and a terminal ferrule. This material shall afford adequate protection against the effects of prolonged exposure to high humidity. The protective coating or enclosure shall be such as to minimize the establishment of leakage paths between terminals, resulting from collection of moisture film on
21、 the exterior surface of the resistor. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-PRF-29C 3 Style Dimensions A max. B .031 C .015 (dia) D .015 (dia) E (dia) F Min. Max. MFA 8.687 9.781 1.140 1.390 .812 1.312 .515 .015 MFB 4.187 5.281 MFD 13.
22、5 16.5 1.156 1.5 +0.010 -0.000 MFE 20.5 23.5 MFF 27.5 30.5 Resistor styles: MFA, MFB, MFD, MFE, and MFF.Resistor styles MFC. Style Dimensions A max. B .031 C .015 (dia) D E .015 (dia) F (dia) G H Min. Max. MFC 1.781 2.937 .812 .937 1.0 .687 1.078 .515 .015 .437 NOTES: 1. All dimensions are in inches
23、. 2. These resistors should be supported by ferrule-terminals only. FIGURE 1. Fixed Resistor. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-PRF-29C 4 3.4.2 Resistance elements. 3.4.2.1 Wirewound. Each resistance element shall be wound on a suit
24、able form with resistance wire. The design of the winding shall be such as to preclude shorting of turns or arcing between turns under the potential imposed between any adjacent turns. 3.4.2.1.1 Resistance wire. The resistance wire shall posses a substantially uniform cross section of conductor and
25、insulation. The wire shall be as free as practicable from particles of impurity and grain growth or other factors contributing to spot weakness. 3.4.2.2 Film. Films shall be uniformly deposited. The film shall be free of blister, thin spots, areas inadequately bonded to core, discolored spots, or ot
26、her blemishes likely to cause flaking or a non-uniform ribbon when spiraled (helixed). Where used, spiraling shall occupy no less than 70 percent of resistor element actual length. The resistor element actual length shall be defined as the nominal distance between terminal bands less three sixty-fou
27、rths of an inch. Designers are CAUTIONED on using these resistors in pulse applications (see 6.5) 3.4.3 Engagement of threaded parts. When threaded parts are used, they shall engage by at least four full threads. 3.4.3.1 Locking of screw-thread assemblies. Screw-thread assemblies shall not loosen as
28、 a result of tests specified herein. 3.5 Terminals. The ends of the resistance element shall be connected to ferrule type terminals, which shall serve for mechanical mounting and electrical connection. The lead wires from the active resistance element to the ferrules shall be so arranged and connect
29、ed that they will be protected from being cut by or placed in contact with the mounting clips at any angle of rotation of the unit. 3.6 Concentricity and parallelism of ferrules. The ferrules shall be so aligned with respect to each other and the resistor body that the maximum permissible departure
30、from concentricity shall be as shown on figure 2. FIGURE 2. Maximum permissible departure from concentricity. 3.7 Ferrules. Ferrules shall be of one piece construction and of a corrosion resistant nonferrous material or shall be protected against corrosion by a coating. 3.8 Resistor units. When a re
31、sistor unit is constructed by joining a number of individual resistance elements together, a means shall be provided for locking the segments securely together to prelude separation or disassembly in the field. There shall be no relative movement among the resistance elements within the housing of t
32、he completed resistor. 3.9 Dielectric withstanding voltage. When resistors are tested as specified in 4.7.2, there shall be no flashover or evidence of insulation breakdown. 5MAL C Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-PRF-29C 5 3.10 In
33、sulation resistance. When measured as specified in 4.7.3, the insulation resistance shall be not less than 1,000 times the nominal resistance value of the resistor being tested (see 3.1). 3.11 DC resistance. When tested as specified in 4.7.4, resistors shall have a dc resistance 0.5 percent of the n
34、ominal resistance specified . 3.11.1 Resistance value deviations. All maximum deviations as specified in this section are to be considered absolute limits with the exception of the contact resistance adjustments. 3.12 Short-time overload. When tested as specified in 4.7.5, resistors shall nor arc, b
35、urn, or char, or show evidence of other damage. The change in resistance shall not exceed 0.5percent. 3.13 Temperature rise. When resistors are tested as specified in 4.7.6, they shall operate continuously without having a hot spot temperature in excess of 110OC. If impregnating compounds are used,
36、there shall be no leakage or external displacement of any of the compounds, regardless of the mounting position, at any ambient temperature up to and including 85OC. 3.14 Resistance temperature characteristics. When resistors are tested as specified in 4.7.7, the resistance change shall not exceed +
37、0.02 percent or -0.005 percent (+200 parts per million (ppm) or -50 ppm) per degree centigrade. 3.15 Thermal shock. When resistors are tested as specified 4.7.8, there shall be no evidence of chipping, crazing, cracking, or spalling of the exterior coating or enclosure. There shall be no evidence of
38、 other mechanical damage. The change in resistance shall not exceed 0.5 percent. 3.16 Salt water immersion cycling. When resistors are tested as specified in 4.7.9, there shall be no evidence of mechanical damage. The change in resistance between the initial and any succeeding measurement shall not
39、exceed 1 percent. 3.17 Vibration. When resistors are tested as specified in 4.7.10, there shall be no evidence of mechanical damage. The change in resistance shall not exceed 0.5 percent. The dielectric withstanding voltage and insulation resistance shall be as specified in 3.9 and 3.10, respectivel
40、y. 3.18 Security of ferrules. When resistors are tested as specified in 4.7.11, there shall be no shifting or loosening of either ferrules or visible relative movement of any of the components of the resistors. 3.19 Mechanical strength. When resistors are tested as specified in 4.7.12, there shall b
41、e no evidence of mechanical damage. 3.20 Marking. Resistors shall be marked in accordance with MIL-STD-1285. The type designation and manufacturers name or code symbol shall be marked on one ferrule (see figure 1), and the maximum rated voltage and current on the other ferrule. There shall be no spa
42、ce between the groups of letters and numbers which comprise the type designation. Marking shall remain legible at the end of all tests. 3.21 Recycled, recovered, or environmentally preferable materials. Recycled, recovered, or environmentally preferable materials should be used to the maximum extent
43、 possible provided that the material meets or exceeds the operational and maintenance requirements, and promotes economically advantageous life cycle costs. 3.22 Soldering. When soldering is employed, only noncorrosive fluxes shall be used unless it can be shown that corrosive elements have been sat
44、isfactorily removed after soldering. Electrical connections shall be mechanically secure before and electrically continuous after soldering. 3.23 Workmanship. Resistors shall be processed in such a manner as to be uniform in quality and shall be free from other defects that will affect life, service
45、ability, or appearance. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-PRF-29C 6 4. VERIFICATION 4.1 Classification of inspection. The inspections requirements specified herein are classified as follows: a. Qualification inspection (see 4.4). b.
46、 Retention of qualification (see 4.5). c. Conformance inspection (see 4.6). 4.2 Reliability and quality. 4.2.1 QPL system. The manufacturer shall established and maintain a QPL system. Evidence of such compliance is a prerequisite for qualification and retention of qualification. 4.3 Inspection cond
47、itions. 4.3.1 Inspection conditions. Unless otherwise specified herein, all inspections shall be performed in accordance with the test conditions specified in the “GENERAL REQUIREMENTS” of MIL-STD-202. 4.4 Qualification inspection. Qualification inspection shall be performed at a laboratory acceptab
48、le to the Government (see 6.3) on sample units produced with equipment and procedures normally used in production. 4.4.1 Sample. The number of sample units comprising a sample of resistors to be submitted for qualification inspection shall be as specified in the appendix A to this specification. (se
49、e A.3.1) 4.4.2 Test routine. Sample units will be subjected to the qualification inspection specified in table II, in the order shown. TABLE II. Qualification inspection. Inspection Requirement paragraph Method paragraph Number of defects allowed Visual and mechanical inspection 3.1, 3.3 to 3.7 inclusive, 3.20 to 3.23 inclusive 4.7.1 0 Dielectric withstanding voltage 3.9 4.7.2 Insulation resistance 3.10 4.7.3 DC resistance 3.
