Standard No.:	GJB 1521-1992
English Name:	General specification for pulse, low power transformers
Chinese Name:	小功率脉冲变压器总规范
Professional Classification:	GJB    Professional Standard - Military
Issued on:	1992-10-28
Implemented on:	1993-6-1
Status:	superseded
Superseded by:	GJB 1521A-2013 General specification for pulse, low power transformers
Superseded on:	2013-10-1
Language:	English
File Format:	PDF
Word Count:	21000 words
Price(USD):	1200.0
Delivery:	via email in 1 business day

Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative. General specifications for low-power pulse transformers 1 Scope 1.1 Subject content This specification specifies the general requirements, quality assurance provisions and test methods for low power pulse transformer for electronic and communication device. 1.2 Application scope This specification is applicable to low-power pulse transformers with a peak pulse power not greater than 300 W and an average power no greater than 5 W. 1.3 Classification 1.3.1 Model designation The model specification of low-power pulse transformer (hereinafter referred to as transformer) shall be in the following form and shall comply with the provisions of the detailed specifications. Component Grade Class Expected life Turns ratio (1.3.2) (1.3.3) (1.3.4) (1.3.5) (1.3.6) 1.3.2 Name code The two letters "TP" are used to represent military low-power pulse transformer. 1.3.3 Grade The grade is identified by a single digit denoting metal encased, encapsulated, or open-type construction, and the ability of the transformers to withstand the environmental tests of Table 1.   Table 1 Grade Test Grade 4 Metal encased Grade 5 Encapsulated Grade 6 Metal encased Grade 7 Encapsulated Grade 8 Open type Vibration of lower frequency × × × Vibration of hight frequency × × Shock × × × × × Temperature shock × × × × × Immersion × × × × Moisture resistance × × × × × Flammability × × × Note: "×” indicates that the test item shall be carried out. 1.3.3.1 Grade 4 and Grade 6. Grade 4 and Grade 6 transformers are sealed, metal encased with separately fabricated headers and terminals. The grades do not include transformers which are encapsulated in a metal shell with an opening in either end or side of the shell, or with insulated lead wires extending through the metal shell. 1.3.3.2 Grade 5 and Grade 7. Grades 5 and 7 transformers are encapsulated, including molded or embedded constructions, and transformers with a metal shell, open at one or both ends and filled with encapsulant material. 1.3.3.3 Grade 8. Grade 8 transformers are open transformers, including transformers of end-sealed structure. 1.3.4 Class The class is identified by a single letter in accordance with Table 2, and denotes the maximum operating temperature (temperature rise (see 4.6.13) at which the expected life in Table 3 can be achieved plus maximum environmental temperature (see 6.3).   Table 2 Class Symbol Maximum operating temperature ℃ Q R S T U V 85 105 130 150 170 >170, as specified 1.3.5 Expected life A letter that meets the requirements of Table 3 is used to represent the expected life (see 6.5). Table 3 Expected life Symbol Expected life h X Y Z Minimum value of 10,000 Minimum value 2,500 As required (see 3.1) 1.3.6 Turns ratio (see 6.6) Four numbers are used to represent the most basic turns ratio of four-winding transformer. For two-winding transformers, the last two numbers shall be zero; for three-winding transformers, the last number shall be zero. The turns ratio marking code is as follows: Turns ratio Symbol 1:1 (two-winding) 1100 1:2 (two-winding) 1200 1:1:1 (three-winding) 1110 1:1:1:1 (four-winding) 1111 Non-standard NNNN 1.3.6.1 For transformers with non-standard turns ratio (for example, 7.1: 6; 7: 5.3) or transformers with more than four windings, the marking code shall be "NNNN". 1.3.7 Type A letter meeting those shown in Figure 1 is used to represent the type. Type A radial terminal Type B double-end terminal Type C unidirectional terminal Type D standard 9-pin tube base J9-1 Type E standard 7-pin tube base J7-1 Type L dual in-line 14 terminal Type M dual in-line 16 terminal Figure 1 Outline structure chart 2 Normative references The valid versions of the following documents within the scope specified in this specification constitute parts of this specification. In case of any discrepancy between the text of this specification and the cited documents, the provisions of this specification shall prevail. GB 191 Packaging - Pictorial marking for handling of goods GB 787 Dimensions of electronic tube bases GB 2423.28 Basic environmental testing procedures for electric and electronic products - Test T: Soldering GB 5048 Moisture-proof packaging GJB 150.10 Environmental test methods for military equipments - Fungus test GJB 179 Sampling procedures and tables for inspection by attributes GJB 360.1 Test methods for electronic and electrical component parts - General GJB 360.2 Test methods for electronic and electrical component parts - Salt spray test GJB 360.4 Test methods for electronic and electrical component parts - Immersion test GJB 360.5 Test methods for electronic and electrical component parts - Barometric pressure test (reduced) GJB 360.6 Test methods for electronic and electrical component parts - Moisture resistance test GJB 360.7 Test methods for electronic and electrical component parts - Temperature shock test GJB 360.11 Test methods for electronic and electrical component parts - Flammability (external flame) test GJB 360.13 Test methods for electronic and electrical component parts - Vibration test of lower frequency GJB 360.15 Test methods for electronic and electrical component parts - Vibration test of hight frequency GJB 360.17 Test methods for electronic and electrical component parts - Impact shock test GJB 360.18 Test methods for electronic and electrical component parts - Solderability test GJB 360.20 Test methods for electronic and electrical component parts - Resistance to soldering heat GJB 360.21 Test methods for electronic and electrical component parts - Terminal strength test GJB 360.23 Test methods for electronic and electrical component parts - Shock (specified pulse) test GJB 360.25 Test methods for electronic and electrical component parts - Resistance to solvents GJB 360.27 Test methods for electronic and electrical component parts - Dielectric withstanding voltage test GJB 360.28 Test methods for electronic and electrical component parts - Insulation resistance test GJB 548 Test methods and procedures for microelectronic device 3 Requirements 3.1 Specification sheets The individual product requirements shall be as specified herein and in accordance with the specification sheets. In the event of any conflict between the requirements of this specification and the specification sheets, the latter shall govern. 3.2 Qualification Transformers furnished under this specification shall be products that have been identified as qualified or approved. 3.3 Materials The materials used in the structure of the transformer shall comply with the relevant material standards, which will enable the transformers to meet the performance requirements of this specification. Materials used for manufacturing transformers shall be non-flammable and non-explosive materials. Corrosive materials used in the manufacturing process shall be removed or neutralized to ensure that no corrosion will occur due to the use of such materials. Insofar as practicable, materials used in the construction of transformers shall be noncorrosive. When it comes to electrical properties, only natural color materials without dyes shall be used.   3.4 Design and construction 3.4.1 Screws and nuts The threads of the screws and riveting nuts for installation and terminal shall meet those specified in common thread series standards. The maximum torque during assembly shall be as follows: Screw size Torque (N·m) M 2.5 0.3 M 3 0.5 M 4 0.6 M 5 0.8 M 6 0.8 M 8 0.8 Nuts shall run down to within two threads of mounting surface. 3.4.2 Terminal Terminals shall meet the requirements of 3.4.2.1, 3.4.2.2, 3.4.2.3 and 3.4.2.4, respectively, as applicable. If other types of terminals are used, these terminals shall meet relevant requirements (see 3.1). 3.4.2.1 Hard wire terminal For the uninsulated wire terminals of Type A, B or C (see Figure 1), the length shall be not less than 40 mm and the diameter shall be not less than 0.5 mm. 3.4.2.2 Pin-type terminal Pin-type terminals of Type D or E (see Figure 1) used in conjunction with electron tube socket shall meet the requirements of J7-1 standard 7-pin tube base or J9-1 standard 9-pin tube base specified in GB 787. Pins for Type L and M terminals shall be in accordance with relevant requirements (see 3.1). 3.4.2.3 Solder terminal The solder terminals may be of any shape and are easy to weld. The height of the solder terminal shall be considered as the maximum distance from the terminal mounting surface to the highest point, including the additional height obtained if semi-flexible terminals are straightened. (It is not intended that the "hook" in the hook-type terminal be straightened from its normal hooked position.) The type of terminal and the maximum size of wire, which the terminal will accept externally, shall be as specified (see 3.1). 3.4.2.4 Screw terminal When specified (see 3.1, external screw terminals shall be supplied with two nuts, two flat washers, and one lockwasher. For cased transformers, the height of the terminal assembly shall be the distance from the free end of the screw to the terminal mounting surface. The type of terminal, size of screw thread, and the exposed length of threads shall be as specified (see 3.1). 3.4.3 Mounting studs When specified (see 3.1), external mounting studs shall be provided with a flat washer and locknut, or with a flat washer, lockwasher, and a nut. 3.4.4 Internal wire leads Internal wire leads shall provide adequate electrical connection and mechanical strength. 3.4.5 Paint If the specified surface is painted (see 3.1), the paint color shall be light and semi-glossy. The manufacturer shall not paint the mounting surface. 3.4.6 Shell material Unless otherwise specified (see 3.1), the shell may be made of metal material or non-metal material. 3.4.7 Magnetic core If required (see 3.1), the magnetic core shall be connected to the shell and grounded, and the magnetic core shall be able to be connected in electrical terms. 3.4.8 Potting, filling, or encapsulating material The amount and coverage of potting, filling, or encapsulating material used shall be essentially the same for all units of a specific design. Potting, filling, or encapsulating material shall not flow from the shell of the transformer during any of the applicable tests. 3.5 Solderability When tested as specified in 4.6.2, transformers shall meet the applicable criteria for terminal evaluation in the test method. 3.6 Resistance to solvents When transformers are test as specified in 4.6.3, there shall be no evidence of mechanical damage, and the markings shall remain legible. Paint coating or surface coating shall not show signs of softening, peeling or other deterioration. 3.7 Aging According to the requirements, if specified (see 3.1), the transformers are tested as specified in 4.6.4, there shall be no evidence of physical and mechanical damage, and the specified electrical test requirements shall be met. 3.8 Resistance to soldering heat When transformers are tested as specified in 4.6.5, there shall be no softening of insulation, or loosening of the winding or terminals. 3.9 Terminal strength When transformers are tested as specified in 4.6.6 to 4.6.6.3, there shall be no evidence of loosening, rupturing, or other mechanical damage of the terminal. Bends shall not be considered as damage unless terminal surface cracking is evident. Except for flexible leads, there shall be no rotation of the terminals. 3.10 Seal When transformers are test as specified in 4.6.7, there shall be no evidence of liquid leakage or bubble overflow. 3.11 Dielectric withstanding voltage When transformers are tested as specified in 4.6.8, there shall be no arcing, flashover, breakdown on insulation, or other evidence of damage. Leakage current shall not exceed that specified in the specification sheets. 3.12 Induced voltage When transformers are tested as specified in 4.6.9, there shall be no continuous arcing or breakdown on insulation, or any sudden change of input current. 3.13 Winding continuity When transformers are tested as specified in 4.6.10, all windings shall be electrically continuous. 3.14 Insulation resistance When transformers are tested as specified in 4.6.11, the minimum insulation resistance shall meet those specified in relevant specification sheets and be not less than one of the following values: a. 10,000MΩ b. 1,000MΩ c. 100MΩ 3.15 Electrical characteristics (including waveform parameters) When transformers are tested as specified in 4.6.12, the applicable electrical characteristics (including waveform parameters as defined according to 6.6) shall be as specified (see 3.1). 3.16 Temperature rise When transformers are tested as specified in 4.6.13, the temperature rise of any winding above the specified maximum ambient temperature (see 3.1) shall not exceed the value specified (see 3.1), and there shall be no evidence of physical damage. 3.17 Life When transformers are tested as specified in 4.6.14, there shall be no evidence of physical or electrical damage as indicated by an open circuit (a break in the continuity of any electrical circuit within the transformer tested) or short circuit occurring within the transformer (such as shorted turns or faulty insulation between layers, between turns, between windings, between winding and shell or core, or between windings and shield). In addition, transformers shall meet the following requirements: a. Insulation resistance——Shall be as specified in 3.14. b. Dielectric withstanding voltage (at atmospheric pressure)——Shall be as specified in 3.11. c. Induced voltage——Shall be as specified in 3.12. The electrical characteristics shall remain within the tolerance or limits specified (see 3.1).   3.18 Salt spray (If required, see 3.1) When transformers are tested as specified in 4.6.15, there shall be no evidence of corrosion as exhibited by any visible degradation of the surfaces that can be attributed to flaking, pitting, blistering or otherwise loosened protective coating or metal surface. 3.19 Vibration When transformers are tested as specified in 4.6.16, there shall be no leakage of filling material and no evidence of other physical damage such as cracks, bursting, or bulging of the shell. 3.20 Shock When transformers are tested as specified in 4.6.17, there shall be no leakage of filling material and no evidence of other physical damage such as cracks, bursting, or bulging of the shell or corrosion affecting the mechanical or electrical operation. 3.21 Temperature shock When transformers are tested as specified in 4.6.18, there shall be no leakage of filling material; and no evidence of other physical damage such as cracks, bursting, or bulging of the shell or corrosion affecting the mechanical or electrical operation. 3.22 Water immersion When transformers are tested as specified in 4.6.19, there shall be no leakage of filling material and no evidence of other physical damage such as cracks, bursting, or bulging of the shell or corrosion affecting the mechanical or electrical operation. 3.23 Moisture resistance When transformers are tested as specified in 4.6.20, there shall be no leakage of filling material; and no evidence of other physical damage such as cracks, bursting, or bulging of the shell or corrosion affecting the mechanical or electrical operation. 3.24 Overload When the transformers are tested as specified in 4.6.21, there shall be no leakage of filling material, no evidence of other physical damage such as cracks, bursting, or bulging of the case.   3.25 Visual and mechanical examination (post test) When the transformers are examined as specified in 4.6.1.1.1, not more than 10 percent of the surface shall have peeling, flaking, chipping, cracking, crazing, or other impairment of the protective coating. There shall be no leakage of the filling material, no evidence of other physical damage, such as cracks, bursting, or bulging of the shell or corrosion affecting the mechanical or electrical operation of the transformers. 3.26 Flammability When the transformers are tested as specified in 4.6.22, there shall be no evidence of violent burning which results in an explosive-type fire, and the coating material used on the transformers shall be self-extinguishing. A transformer shall not be considered to have failed, in the event that it is consumed by the applied flame, unless dripping of flaming material or an explosive-type flame has occurred. A transformer shall be considered to have failed only if an explosion of dripping of flaming material occurs, an explosive-type flame is produced, or if visible burning continues beyond the allowable duration of 3 minutes after removal of the applied flame. Material will be considered self-extinguishing if the following conditions are met: a. The duration of visible flame does not exceed 3 minutes after removal of the applied flame. b. There is no explosion, nor any violent burning which results in an explosive-type flame. c. There is no dripping of flaming material from the transformer under test. 3.27 Fungus (if required, see 3.1) All external materials shall be nonnutrient to fungus growth or shall be suitably treated to retard fungus growth. The manufacturer shall certify that all external materials are fungus resistant (see 4.6.23) or shall perform the test specified in 4.6.23. There shall be no evidence of fungus growth on the external surfaces. 3.28 Marking Each transformer shall be clearly marked, and its contents shall at least include product model or mark; manufacture date or production batch number. The marking may be applied to more than one side of the shell if the required marking necessitates more space than is available on the one side. Where the surface areas are insufficient for all of the required information, as many as possible of the markings shall be applied using the order of priority as listed above. Markings shall remain legible after all tests. Any markings of a classified nature shall not be included. Unless otherwise specified (see 3.1), terminals shall be identified by appropriate numbers. Where space does not permit numbering, terminals shall be identified by color coding in accordance with Table 4. Table 4 Terminal color code Black 0 Brown 1 Red 2 Orange 3 Yellow 4 Green 5 Blue 6 Violet 7 Gray 8 White 9 3.29 Workmanship The transformers shall be processed in such a manner as to be uniform in quality and shall meet the requirements of 3.3, 3.4, and 3.28, as applicable, and shall be free of defects that will affect life or appearance. 4 Requirements for quality assurance 4.1 Responsibility for inspection Unless otherwise specified in the contract or order, the manufacturer shall be responsible for completing all inspection items specified in this specification. Unless otherwise specified in the contract or order, the manufacturer may use its own or any other facilities suitable for completing the inspections specified in this specification, except those not be allowed for use by the competent department concerned. If necessary, the ordering party or superior competent department has the right to examine any of the inspection items described in the specification. 4.1.1 Responsibility for qualification All products must meet all requirements given in clauses 3 and 5 of the specification. The inspections specified in this specification shall be an integral part of the entire inspection system or quality program of the manufacturer. If the contract includes inspection requirements not specified in this specification, the manufacturer shall also ensure that the products submitted for acceptance meet the contract requirements. It is neither allowed to submit products that are known to be defective in quality conformance sampling, nor to require the ordering party to receive defective products.   4.1.2 Test equipment and inspection facilities Test and measuring equipment and inspection facilities of sufficient accuracy, quality and quantity to permit performance of the required inspection shall be established and maintained by the manufacturer. At the same time, a calibration system to control accuracy of the measuring and test equipment shall be established and maintained. 4.2 Classification of inspections The inspections included in this specification shall be classified as follows: a. Qualification inspection (see 4.4); b. Conformance inspection (see 4.5). 4.3 Inspection conditions Unless otherwise specified herein, all inspections shall be performed under the standard atmospheric conditions specified in clause 4 of GJB 360.1. 4.3.1 Test frequency When a nominal test frequency is specified herein, the frequency used shall be within ±2 percent of the nominal value. 4.3.2 Test voltage During the dielectric withstanding voltage test, the peak value of the applied test voltage shall not exceed 5% of the peak value of the standard sine wave voltage. 4.4 Qualification inspection Qualification inspection shall be performed at a laboratory acceptable to the competent department concerned (see 6.2) on sample produced with equipment and procedures normally used in production. 4.4.1 Qualification of transformers based on complete testing 4.4.1.1 Sample size The number of sample of transformers to be submitted for inspection shall be as specified in Annex A.   4.4.1.2 Inspection procedures The samples shall be subjected to qualification inspection in accordance with the test items and order shown in Table 5, as well as the provisions in Annex A of this specification. Table 5 Qualification inspection Examination or test Grade Requirement paragraph Method paragraph 4 5 6 7 8 Group I (4 samples) Solderability 2) × × × × × 3.5 4.6.2 Resistance to solvents (4 samples) 1) × × × × × 3.6 4.6.3 Group II (all samples) Aging (when specified) × × × × × 3.7 4.6.4 Visual and mechanical examination (external) × × × × × 3.1 and 3.3 3.4~3.4.2.3 3.4.5~3.4.7 3.28~3.29 4.6.1.1 Resistance to soldering heat 2) × × × × × 3.8 4.6.5 Terminal strength × × × × × 3.9 4.6.6 Seal × × × × 3.10 4.6.7 Dielectric withstanding voltage (at atmospheric pressure) × × × × × 3.11 4.6.8.1 Dielectric withstanding voltage (at reduced barometric pressure) (When applicable) × × 3.11 4.6.8.2 Induced voltage × × × × × 3.12 4.6.9 Winding continuity × × × × × 3.13 4.6.10 Insulation resistance × × 3.14(a) 4.6.11 Insulation resistance × × 3.14(b) 4.6.11 Insulation resistance × 3.14(c) 4.6.11 Electrical characteristics (including waveform parameters) × × × × × 3.15 4.6.12 Temperature rise (2 samples) × × × × × 3.16 4.6.13 Group III (2 samples) Life × × × × × 3.17 4.6.14 Induced voltage × × × × × 3.12 4.6.9 Winding continuity × × × × × 3.13 4.6.10 Insulation resistance × × 3.14(a) 4.6.11 Insulation resistance × × × 3.14(b) 4.6.11 Insulation resistance × 3.14(c) 4.6.11 Dielectric withstanding voltage (at reduced voltage) × × × × × 3.11 4.6.8.4 Electrical characteristics (including waveform parameters) × × × × × 3.15 4.6.12 Visual and mechanical examination (external) × × × × × 3.1 and 3.3 3.4~3.4.2.3 3.4.4~3.4.7 3.28~3.29 4.6.1.1 Group 4 (6 samples) Salt spray (when required) × × × × 3.18 4.6.15 Vibration (lower frequency) × × × 3.19 4.6.16.1 Vibration (hight frequency) × × 3.19 4.6.16.2 Shock × × × × × 3.20 4.6.17 Winding continuity × × × × × 3.13 4.6.10 Induced voltage × × × × × 3.12 4.6.9 Dielectric withstanding voltage (at reduced voltage) × × × × × 3.11 4.6.8.4 Temperature shock × × × × × 3.21 4.6.18 Winding continuity × × × × × 3.13 4.6.10 Immersion × × × × 3.22 4.6.19 Moisture resistance × × × × × 3.23 4.6.20 Induced voltage × × 3.12 4.6.9 Winding continuity × × 3.13 4.6.10 Insulation resistance × × 3.14(a) 4.6.11 Dielectric withstanding voltage (at reduced voltage) × × 3.11 4.6.8.4 Overload × × × 3.24 4.6.21 Induced voltage × × × 3.12 4.6.9 Winding continuity × × × 3.13 4.6.10 Insulation resistance × × × 3.14(b) 4.6.11 Insulation resistance × 3.14(c) 4.6.11 Dielectric withstanding voltage (at reduced voltage) × × 3.11 4.6.8.4 Visual and mechanical examination (external) (post test) × × × × × 3.25 4.6.1.1.1 Electrical characteristics (including waveform parameters) × × × × 3.15 4.6.12 Flammability (2 samples) × × × 3.26 4.6.22 Visual and mechanical examination (internal) (3 samples) × × × × × 3.3, 3.4.4, 4.6.1.2 3.4.7, 3.4.8 3.29 Group V Fungus 3) × × × × × 3.27 4.6.23 Notes: 1) Printed circuit type transformers only, or when specified (see 3.1). 2) Solderable type terminals only: If the soldering iron method (4.6.2.2) of the solderability test is performed, then the resistance to soldering heat test (4.6.5.2) need not be performed. 3) Test shall not be performed if the manufacturer provides certification that all external materials are fungus resistant. 4) "×” indicates that the test item shall be carried out.

1 Scope 1.1 Subject content 1.2 Application scope 1.3 Classification 2 Normative references 3 Requirements 3.1 Specification sheets 3.2 Qualification 3.3 Materials 3.4 Design and construction 3.5 Solderability 3.6 Resistance to solvents 3.7 Aging 3.8 Resistance to soldering heat 3.9 Terminal strength 3.10 Seal 3.11 Dielectric withstanding voltage 3.12 Induced voltage 3.13 Winding continuity 3.14 Insulation resistance 3.15 Electrical characteristics (including waveform parameters) 3.16 Temperature rise 3.17 Life 3.18 Salt spray 3.19 Vibration 3.20 Shock 3.21 Temperature shock 3.22 Water immersion 3.23 Moisture resistance 3.24 Overload 3.25 Visual and mechanical examination (post test) 3.26 Flammability 3.27 Fungus (if required, see 3.1) 3.28 Marking 3.29 Workmanship 4 Requirements for quality assurance 4.1 Responsibility for inspection 4.2 Classification of inspections 4.3 Inspection conditions 4.4 Qualification inspection 4.5 Quality conformance inspection 4.6 Methods of inspection 5 Delivery preparation 5.1 Packaging 5.2 Marking 5.3 Transport 5.4 Storage 6 Instructions 6.1 Ordering document information 6.2 Qualification (see 3.2) 6.3 Temperature and life 6.4 Instructions for aviation application 6.5 Increase in environmental temperature during overload test 6.6 Definitions of waveform parameters Annex A (Supplement) Procedures for qualification inspection