MIL-STD-202H.pdf - 第280页

MI L - S TD - 202 - 30 9 M E TH O D 30 9 VOL T AG E C O EF F I C I EN T O F R ESI ST AN C E D E T ER M I N A T I O N PR O C E DURE 1. SCOPE 1. 1 P urpose . C ertain t y pes of r es i s t or s ex hi bi t a v ar i at i on …

MIL-STD-202-309

CONTENTS

PARAGRAPH PAGE

FOREWORD…………………………………………………………. ii

1. SCOPE 1

1.1 Purpose………………………………………….……..…………. 1

1.2 Precautions………………………………….……..…….………. 1

2. APPLICABLE DOCUMENTS 1

3. DEFINTIONS 1

4. GENERAL REQUIREMENTS 1

4.1 Procedure…………..…….………………………..….….…..….. 1

5. DETAILED REQUIREMENTS 2

5.1 Summary…………………………………………..…..…………. 2

6. NOTES 2

6.1 Supersession data………………………………………………. 2

iii

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MIL-STD-202-309

METHOD 309

VOLTAGE COEFFICIENT OF RESISTANCE DETERMINATION PROCEDURE

1. SCOPE

1.1 Purpose. Certain types of resistors exhibit a variation of resistance with changes in voltage across the resistor.

This is a measurable characteristic; a test to determine the magnitude of such a characteristic is the Voltage

Coefficient of Resistance Determination Procedure.

1.2 Precautions. Adherence to 4.1, applying voltage intermittently for not more than the total of 0.5 seconds in any

5 second interval is emphasized as an important consideration of this method. Failure to comply would result in a

voltage coefficient of vast variations. A resistance measuring device capable of withstanding high voltage

applications should be used. Certain types of resistors exhibit a variation of resistance with changes in potential

difference, this effect being separate and distinct from the change in resistance due to heating effect whether from

applied voltage or ambient conditions.

2. APPLICABLE DOCUMENTS

This section not applicable to this standard.

3. DEFINTIONS

This section not applicable to this standard.

4. GENERAL REQUIREMENTS

4.1. Procedure. The voltage coefficient is applicable only to resistors of 1,000 ohms and over. Unless otherwise

specified in the individual specification, all measurements and tests shall be made at a temperature of 25°C ±5°C.

Adjust the resistance measuring device to apply 0.1 X rated continuous working voltage to the resistor. Measure the

resistance by applying this voltage intermittently for not more than the total of 0.5 second in any 5 second interval.

Readjust the resistance measuring device to apply 1.0 X rated continuous working voltage to the resistor and repeat

the above intermittent measuring procedure. Compute the Voltage Coefficient (VC) as follows:

9.0

100)( −

Where:

R = Resistance at rated continuous working voltage.

r = Resistance at 0.1 rated continuous working voltage.

E = Rated continuous working voltage.

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MIL-STD-202-309

5. DETAILED REQUIREMENTS

5.1. SUMMARY. The following detail is to be specified in the individual specification:

The continuous working voltage (see 4.1).

6. NOTES

(This section contains information of a general or explanatory nature that may be helpful, but is not mandatory.)

6.1 Supersession data. The main body and 38 parts of this revision of MIL-STD-202 replace superseded MIL-STD-

202.

Custodians: Preparing activity:

Army - CR DLA – CC

Navy - EC

Air Force - 85 (Project 59GP-2015-039)

DLA - CC

Review activities:

Army - AR, AT, AV, CR4, MI, SM, TE

Navy - AS, OS, SH

Air Force - 19, 99

NSA - NS

NOTE: The activities listed above were interested in this document as of the date of this document. Since

organizations and responsibilities can change, you should verify the currency of the information above using the

ASSIST Online database at https://assist.dla.mil/

北测（上海）电子科技有限公司

联系方式：xuyj@beice-sh.com 13917165676