1、MILITARY SPECIFICATION TRANSFORMERS, VARIABLE, POWER GENERAL SPECIFICATION FOR 1.1 Scope. This specification covers general requirements for tapped and iuously variable transformers which are either manually operated or motor driven. Included are variable transformers for aircraft light dimming cont
2、rols (see 6.1). 1.2 Classification. Transformers covered by this specification shall be of the following classifications (see 3.1 and 6.2.1). Class I - Transformers exceeding 2 pounds in weight; Class II - Transformers weighing 2 pounds or less. 2. APPLICABLE DOCUMENTS 2.1 The following documents of
3、 the issue in effect on the date of invitation for bids or request for proposal, form a part of the specification to the extent specified L-P-513 NN-P-71 QQ- S- 5 7 1 QQ-S- 781 PPP-B-566 PPP-B-585 PPP-B-601 PPP-B-621 PPP-B-636 PPP-B-676 PPP-T-60 PPP-T- 76 Plastic Sheet, Laminated, Thermosetting, Pap
4、er-Base, Pallets, Materials Handling, Wood, Double Faced, Solder, Tin Alloy: Tin-Lead Alloy; and Lead Alloy. Strapping, Steel, Flat and Seals. Boxes, Folding, Paperboard. Boxes , Wood , Wirebound. Boxes , Wood, Cleated-Plywood. Boxes, Wood, Nailed and Lock-Corner. Boxes, Shipping, Fiberboard. Boxes,
5、 Setup. Tape, Packaging, Waterproof. Tape, Pressure-Sensitive Adhesive, Paper, (For Carton Phenolic-Resin. Stringer Construction. Sealing). MILITARY MIL-1-10 - Insulating Compound, Electrical, Ceramic, Class L. MIL-M- 14 - Molding Plastics and Molded PlasticParts, Thermosetting. MIL-W- 76 - Wire and
6、 Cable, Hookup, Electrical, Insulated. MIL-P-116 - Preservation-Packaging, Method of. MIL- W- 5 8 3 - Wire, Magnet, Electrical. MIL-P-997 - Plastic Material , Laminated, Thermosetting, Electrical MIL-S-3950 - Switches Toggle, Environmentaily Sealed, MIL-S-8805 - Switches and Switch semblies, Sensiti
7、ve,/ and Push MIL-F-14256 - Flux, Soldering, Liquid (Resin Base). MIL-P-15037 - Plastic Sheet, Laminated, Thermosetting, Glass-Cloth, Insulation) General Specification For. (Snap Action), General Specification for. Sheets, Glass Cloth, Silicone Resin. Melamine-Resin. Provided by IHSNot for ResaleNo
8、reproduction or networking permitted without license from IHS-,-,- Plastic-Material, Laminated Thermosetting, Sheets, - Enamel, Equipment, Light-Gray (Formula No. 111). - Wire, Electrical, Insulated, High Temperature. - Boxes: Water Resistant Paperboard, Folding, Set-up, and - Calibration System Req
9、uirements. - Transformer, Variable, Power, 400 Hz. Nylon Fabric Base, Phenolic-Resin. Metal-Stayed. MIL-STD-129 - Marking for Shipment and Storage. MIL-STD-147 - Palletized Unit Loads on 40“ x 48“ Pallets. MIL-STD-202 - Test Methods for Electronic and Electrical Component MIL-STD-462 - Electromagnet
10、ic Interference Characteristics, Measure- MIL-STD-810 - Environmental Test Methods. MIL-STD-831 - Test Reports, Preparation of. MIL-STD- 1285 - Marking of Electrical and Electronic Parts. - Shaft, Control Knob. Parts. ments of. (Copies of specifications, standards, drawings, and publications require
11、d by suppliers in connection with specific procurement functions should be obtained from the procuring activity or as directed by the contracting officer.) 2.2 Other publications. The following document forms a part of this specification to the extent specified herein. Unless otherwise indicated, th
12、e issue in effect on date of invitation for bids or request for proposal shall apply. NATIONAL BUREAU OF STANDARDS Handbook H28 - Screw-Thread Standards for Federal Services. Applicatiox for copies should be addressed to the Superintendent of Documents, - Government Printing Office, Washington, D.C.
13、, 20402.) 3. REQUIREMENTS 3.1 Specification sheets. The individual part requirements shall be as specified herein and in accordance with the applicable specification sheets or drawings. event of any conflict between this specification and the specification sheet or drawing, the latter shall govern.
14、In the 3.2 First article inspection. Transformers furnished under this specification shall be products which have been tested and have passed the first article inspection specified in 4.5. 3.3 Materials. The materials shall be as specified herein; however, when a definite material is not specified,
15、a material shall be used which will enable the transformers to meet the performance requirements of this specification. or approval of any constituent material shall not be construed as a guaranty of the acceptance of the finished product. Acceptance 2 Provided by IHSNot for ResaleNo reproduction or
16、 networking permitted without license from IHS-,-,-MIL- T- 8 37 2 1 3.3.1 Substitution of materials. If the supplier desires to substitute another material for a specified material or fabrtcated part, he shall submit a statement to the Government describing the proposed substitution, together with e
17、vidence to substantiate his claim that such substitute is suitable. At the discretion of the Government, test samples may be required to prove the suitability of the proposed substitute. obtained in writing from the Government. Before substitutions are made, approval for each substitution shall be 3
18、.3.2 Flammable materials. Materials used in constructing these transformers shall be : (a) For class I - Nonflammable and nonexplosive, insofar as practicable. When this is not practicable, all materials shall be self- extinguishing (see 6.4.4). (b) For class II - Nonflammable and nonexplosive. 3.3.
19、3 Corrosive materials. Corrosive materials used in any of the manufacturing processes shall be removed or neutralized so that no corrosion will result from such use. Insofar as practicable, materials used in the construction of transformers shall be noncorrosive. 3.3.4 Insulating materials. The insu
20、lating materials used shall not support combustion, emit explosive gases or give off toxic to arcs (such as those caused by a short circuit). fillers will not be permitted in parts that may be subjected to arcing or surface creepage. or noxious gases when subjected Plastic materials with cellulose 3
21、.3.4.1 Laminated phenolic. When electrical characteristics are involved, only natural uncolored materials shall be used. Laminated phenolic materials shall conform (a) For class I - MIL-P-997, L-P-513, MIL-P-15037, and MIL-P-15047. (b) For class II - MIL-P-997 and MIL-P-15037. 3.3.4.2 Molded phenoli
22、c or melamine. Molded phenolic or melamine materials shall conform to MIL-M- 14 or equivalent. 3.3.4.3 Ceramic (external use). Ceramic materials shall conform to MIL-1-10. 3.3.5 Wire. 3.3.5.1 Magnet wire. Magnet wire shall conform to the types and sizes specified in MIL-W-583. magnet wire are used.
23、Government approval shall be required when other types and sizes of 3.3.5.2 Insulated wire. When insulated wire is used as wire terminals, the wire shall be of the types and sizes covered in MIL-W-76 or MIL-W-16878. shall be required when other types and sizes of insulated wire are used as terminals
24、. 3.3.5.3 Leads, (class II only). The leads to external terminals shall be Government approval stranded wire, unless otherwise specified (see 3.1 and 6.2.1). 3.3.6 Solder and soldering flux. Solder, when used, shall be in accordance with QQ-S-571. Soldering flux shall be in accordance with MIL-F-142
25、56. 3.3.7 Screws, nuts, and washers. All mounting and terminal screws, nuts, and washers shall be of corrosion-resistant material or shall be protected against corrosion. 3 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-T-83721 5 7777906 0080354
26、 3 MIL-T- 8372 1 3.4 Design and construction. 3.4.1 Mounting screws and mounting inserts. Screw threads shall be class 2A or 2B, as applicable (see 3.1 and 6.2.1), in accordance with Handbook H28. External screw threads, class 2 fit, after receiving a finish, shall be capable of accepting a nut of c
27、lass 28 fit. Internal screw threads, class 2 fit, after receiving a finish, shall be capable of accepting a screw of class 2A fit. Maximum installation torque shall be in accordance with the following: Screw size Torque (pounds - inches) .112-40 UNC - - - - - - - - 3 .138-32 UNC - - - - - - - - 5 .1
28、64-32 UNC - - - - - - - - 6 8 .1go-32 UNC - - - - - - - - .250-20 UNC - - - - - - - - 8 -312-18 UNC - - - - - - - - 8 Nuts shall run down to within two threads of mounting surface. visible on the terminal stud after all hardware and attached circuitry is placed on the Two threads shall be 3.4.2 Term
29、inals. 3.4.2.1 Solder terminals. Solder terminals may be of any shape, and shall be capable of being readily soldered. as the maximum distance from the terminal mounting surface to the highest point, including the additional height obtained if semiflexible terminals are straightened. of terminal and
30、 the maximum size of round wire which the terminal will accept externally shall be as specified (see 3.1 and 6.2.1). The height of the solder terminal shall be considered The type 3.4.2.2 Quick-connect (push-on) terminals. When applicable, quick-connect terminals shall be of the material and physica
31、l dimensions specified (see 3.1 and 6.2.1). 3.4.2.3 Stud-type terminals. When specified (see 3.1 and 6.2.1), external stud terminals shall be supplied with two nuts, two flat washers, and one lockwasher. The height of the terminal assembly shall be the distance from the free end of the stud to the t
32、erminal mounting surface. The type of terminal, size of screw thread, and the exposed length +1/16 inch shall be as specified (e.g., stud, .164-32 UNC-2AX .375) (see 3.1 and 6.2.1). Terminal studs on class II transformers shall be separated by insulation barriers that are greater than the height of
33、the terminal studs. Studs shall be firmly mounted to header and electrical contact surface shall be higher than the header surface. 3.4.3 Mounting studs (when specified) (see 3.1 and 6.2.1). External mounting studs shall be provided with a flat washer and locknut, or with a flat washer, lockwasher,
34、3.4.4 Paint color. When a paint finish is specified (see 3.1 and 6.2.1), the color of the paint for class I transformers shall be light gray, semigloss, formula No. 111, as specified in MIL-E-15C90. Class II transformers shall be painted lusterless black No. 37038 per FED-STD-595, unless otherwise s
35、pecified (see 3.1 and 6.2.1). Unless otherwise specified (see 3.1 and 6.2.1), the manufacturer shall omit paint from the mounting area surface. 3.4.5 Operating shaft. All operating shafts shall be corrosion-resistant metal or have a corrosion-resistant coating or sleeve covering a metal inner shaft.
36、 3.4.5.1 Shaft length. The lengths of standard operating shafts shall be as specified (see 3.1 and 6.2.1). 4 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MI L-T- 83721 3.4.6 Enclosure (when specified)(see 3.1 and 6.2.1). Transformers shall have su
37、itable enclosures for protection against electrical shock and mechanical damage. 3.4.7 Mounting conversion (when specified, see 3.1 and 6.2.1). Transformers shall be easily converted from surface mounting to back-of-panel mounting by removing the knob and sliding shaft through unit so it projects fr
38、om center of mounting plate. shall be capable of being mounted on either end of the shaft. The knob 3.4.8 Index pin (class II only). Transformers shall be designed for mounting on a panel. A nonturn index pin shall be provided as specified (see 3.1 and 6.2.1). 3.4.9 Internal wire leads. Internal wir
39、e leads shall be attached to the coils and other internal components and terminals or case by soldering, welding, brazing, or other method (e.g., lead-sweating or nylon-coated wires) in such a manner as to provide adequate electrical connection and mechanical strength. to provide the electrical conn
40、ection, wire leads shall be anchored mechanically. Where soft solder is used 3.4.10 Core and coil mounting. Cores and coils shall be rigidly secured to prevent The coils shall be protected any permanent change in the relative position of the parts. against injury from the core laminations or the for
41、m the coil is wound on. of securing the core and coil to the devices for mounting the transformers in the equipment (studs, lugs, inserts, brackets, etc.) shall not depend on soft solder alone for mechanical strength nor shall the transmission of the mechanical load of the core to the mounting devic
42、es depend on soft solder. The means 3.4.11 Potting, filling, or encapsxlating 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 ca
43、se of the transformer or inductor during any of the applicable tests. 3.4.12 Stops. Stops shall be used to limit the mechanical travel of the brush assembly and may be a part of but shall not complete any electrical circuit. shall the mechanical stop contact the brush carbon. In no case 3.4.13 Commu
44、tator. The commutator surface shall be evenly wound, free from any foreign matter, and have a smooth surface. 3.4.14 Voltage control. will provide the range of output voltages from the minimum voltage position, to its maximum voltage as specified (see 3.1 and 6.2.1). Where tap switching is employed,
45、 a minimum of 10 taps shall be provided. The transformer shall incorporate a voltage control that 3.4.15 Dimensions. The dimensions of the transformer shall be as speicfied (see 3.1 and 6.2.1). 3.4.16 Weight. The weight of the transformer shall be as specified (see 3.1 and 6.2.1). 3.4.17 Control kno
46、b shaft. The control knob shaft shall conform to MS33742 for the specified nominal size (see 3.1 and 6.2.1). 3.4.18 Meters, fuses, power cords (when specified, see 3.1 and 6.2.1). Meters, fuses, and power cords shall be as specified (see 3.1 and 6.2.1). Military standard items shall be used when app
47、licable. 3.4.18.1 Cased units. Cased units supplied with power cords shall be supplied with three prong plugs; one prong shall be connected to a wire grounded to the case. 3.4.19 Switch (when specified, see 3.1 and 6.2.1). Switches shall conform to . MIL-S-8805. Toggle switches shall conform to MIL-
48、S-3950. 5 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-1 on the commutator over the entire range of mechanical travel. Smooth electrical control of the output voltage and continuous contact between the brush and its terminal shall be maintained ov
49、er the entire range of shaft rotation. The entire rotating assembly shall be insulated from the operating shaft. The brush assembly shall be designed SO that a slight misalinement will not affect the reliability of the brush contact with the commutator. There shall be no contact between the brush holder and the commutator when the carbon is completely worn. holder shall be 0.012 inch. The minimum clearance between commutator and brush 3.5 Resistance to solvents. When transformers are te
