NPFC - MIL-T-27
TRANSFORMERS AND INDUCTORS (AUDIO, POWER, AND HIGH-POWER PULSE), GENERAL SPECIFICATION FOR
| Organization: | NPFC |
| Publication Date: | 4 April 1985 |
| Status: | inactive |
| Page Count: | 67 |
scope:
This specification covers the general requirements for audio, power, and high-power pulse transformers and inductors for use in electronic and communication equipment. This specification covers transformers and inductors weighing 300 pounds or less or having root-mean-square (rms) test-voltage ratings Of 50,000 volts or less, and also high-power pulse transformers where the peak pulse power is greater than 5 watts. Transformer and inductor assemblies incorporating any other active or passive components do not come within the scope of this specification.
The type designation shall be in the following form, and as specified (see 6.1.2).
Transformers and inductors are identified by the two-letter symbol "TF".
The grade is identified by a single digit denoting metal encased, encapsulated, or open-type construction, and the ability of the transformers or inductors to withstand the environmental tests of table I.
Grade 4 units are sealed, metal encased with either separately fabricated headers or terminals or both. This grade does not include units 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.
Grade 5 units are encapsulated, including molded or embedded constructions, and units with a metal shell, open at one or both ends and filled with encapsulant material.
Grade 6 units are open type and are generally intended for subsequent potting, molding, or embedment in an assembly with or without component parts.
Beneficial comments (recommendations, additions, deletions) and any pertinent data which may be of use in improving this document should be addressed to: US Army Electronics Research and Development Command, ATTN: DELET-R-S, Fort Monmouth, NJ 07703, by using the self-addressed Standardization Document Improvement Proposal (DD Form 1426) appearing at the end of this document or by letter. TABLE I. Grade.
Grade 4 Grade 5 Grade 6
Test metal encap- open
encased sulated type
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The class is identified by a single letter in accordance with table II, and denotes the maximum operating temperature (temperature rise (see 4.8.12) plus maximum ambient temperature (see 6.14.3.1 and 6.14.3.3)). TABLE II. Class.
Symbol Maximum operating temperature
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The family is identified by a two-digit symbol in accordance with table III. TABLE III. Family.
03 - Power transformer 04 - Power inductor 20 - Audio inductor 21 - Audio transformer 36 - Pulse transformer 37 - Charging inductor 40 - Saturable transformer 41 - Saturable inductor
The envelope and mounting dimensions are identified by a two-letter symbol in accordance with figure 1.
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