ECA 229-A-1965 Fixed Wire-Wound Precision Resistors.pdf

1、- EIA 229-A 65 m 3234600 0063420 7 m -% r *- 3 O 4 USA S C83.32-1968 Approved July 24, 1968 USA STANDARDS INSTITUTE oc iA Fixed, Wire -Wound, 4 Y Precision Resistors cy N 8 EIA STANDARD R S- 2 2 9mA (Revision of RS-229) May 1965 Engineering Department ELECTRONIC INDUSTRIES ASSOCIATION 7 - EIA 229-A

2、b5 m 3234b00 00b3421 9 m NOTICE EIA engineering standards are designed to serve the public interest through eliminating mis- understandings between manufacturers and purchasers, facilitating interchangeability and improve- ment of products, and assisting the purchaser in selecting and obtaining with

3、 minimum delay the proper product for his particular need. Existence of such standards shall not in any respect preclude any member or non-member of EIA from manufacturing or selling products not conforming to such standards. Recommended standards adopted by EIA are without any regard to whether or

4、not their adop- tion may in any way involve patents on articles, materials, or processes. By such action, EIA does not assume any liability to any patent owner, nor does it assume any obligation whatever to parties adopting the recommended standards. Published by ELECTRONIC INDUSTRIES ASSOCIATION En

5、gineering Department 2001 Eye Street, N.W., Washington, D. C. 20006 8 Electronic Industries Association 1966 All the first four digits represent significant figures and the last digit, the number of zeros to follow. When the value of resistance is less than 1,000 ohms, or when fractional values of a

6、n ohm are required, the letter “R” is substituted for one of the significant digits to represent the decimal point. When the letter “R” is used, succeed- ing figures become significant figures. TABLE VI1 Designation 1R000 to 9R999 incl. IOROO to 99R99 incl. 100RO to 999R9 incl. 10000 to99990 incl. 1

7、0001 to99991 incl. 10002 to99992 incl. 10003 to99993 incl. Resistance Value (Ohms) 1.000 to 9.999 incl. 10.00to 99.99 incl. 100.0 to 999.9 incl. 1,000 to 9,999 incl. 10,000 to 99,990 incl. 100,0001 to 999,900 incl. 1,000,000 to 9,999,000 incl. EIA 229-A 65 W 3234600 0063425 b W RS-22 9-A Page 4 4. S

8、TANDARD TEST CONDITIONS AND METHODS 4.1 Standard Teat Conditions Unless otherwise specified, the atmospheric conditions at which tests are to be made, or referred to, are as follows: l . Temperature .25“C f 5C Barometric Pressure . .28“ to 32“ Hg Relative Humidity . .6% Max. Tests which require cont

9、inuous supervision for periods exceeding 8 hours, may be made so that each cycle falls within the normal 8 hour day. Succeeding cycles may then follow, day by day. All resistance tolerances and resistance change requirements shall have an additional +0.01e allowed to compensate for measuring errors.

10、 I 4.2 Test Requirements The resistor samples shall be divided into three groups. TOTAL SAMPLE LOT I I I .“I GROUP.1 , 171 GROUP 2 I 6 SAMPLES 6 SAMPLES 6 SAMPLES TEMP. COEF. LOAD LIFE. .TERM. STRENGTH TEMP. CYCLING VIBRATION MOISTURE CYCLING DI ELECTRIC a I SOLDERABILITY SALT,WATER DIELECTRIC. Figu

11、re 3 Test shall be made in the order shown on Figure 3. 4.2.1 Visual and Mechanical Inspection Resistors shall be inspected to verify that their physical dimensions, construction, and mark- ing are in accordance with the applicable figure and requirements, and the workmanship is satisfactory. 4.2.2

12、All resistors submitted for test shdJ be within f 0.5% accuracy. 4 EIA 229-A b5 M 3234b00 00b342b 8 RS-229-A Page 5 4.2.3 Recommended values for standard tests. (a) For a specific resistance value required by customer (b) For general type approval Group 1 Style Critical Resistance Value Characterist

13、ic C CRB-52 CRB-53 CRB-54 CRB-55 CRB-56 CRB-62 CRB-63 720K 270K 330K 225K 125K 20K 9K (c) Group 2 and 3 Maximum value for which approval is required. 4.2.4 Resistance (a) Resistors shall have their resistance within the specified resistance tolerance. 4.2.5 Short Time Overload (a) After a measuremen

14、t of resistance, the resistor shall be subjected to a d.c. test potential equivalent to that calculated for twice the rated (100%) wattage, but not to exceed twice the maximum rated voltage for 10 minutes under the following conditions : In free space, predicated on horizontal mounting with no objec

15、t closer than 3 inches to the protective coating except the mounting base, which shall not be closer than 2 inches below the resistors. In still air, with no circulation other than that created by the heat of the resistors being operated. After the resistor has returned to room temperature but, no s

16、ooner than thirty (30) minutes after removal of the test potential, the resistance shall again be measured. (b) As a result of the test specified above there shall be no arcing, burning, charring, or oblit- eration of the marking ; the change in resistance shall not exceed the resistance tolerance s

17、pecified in the type designation or O.l%, whichever is smaller. 4.2.6 Temperature Cycling (a) Mounting, temperature conditions, and measurements. Resistors shall be mounted in such a manner that there is at least 1” of free air space around each resistor, and in such position with respect to the air

18、 stream that the mounting offers substantially no obstruc- tion to the flow of air across and around the resistor. The rate of temperature change within the climate chamber shall be not less than 2C per minute. The temperature shall be maintained at each of the extreme temperatures by means of circu

19、lating air. The air temperature shall be measured by a suitable method and as near the center of the group of resistors as possible. (b) Procedure. Resistors shall be subjected to the temperature cycle shown in table below for a total of five cycles performed continuously. The resistors ,may be tran

20、sferred from one chamber to another, in which case they shall be kept at room temperature for not less than 10 minutes and not more than 15 minutes between exposure to the extreme temperatures. Measurements of resistance shall be made before cycling and not less than 1 hour, but within 24 hours afte

21、r the iast cycle. EIA 229-A 65 m 3234600 0063427 T m Temperature Cycle Sequence Temperatuw (OC) The (Minutes) Startat 25 +5 Reduce to -65 +O, -3 30 Return to 25 +5 10 to 15 145 +3, -0 Return to 25 +5 30 10 to 15 (e) Temperature cycling. Resistors shall withstand the test specified above without mech

22、an- ical damage. The change in resistance shall be not more than 0.2%. 4.2.7 Salt Water Immersion Cycling (a) Conditioning. Resistors shall be conditioned for 1 hour with rated direct-current voltage applied, in an oven maintained at a temperature of 85C (185F). At the end of the conditioning period

23、, the resistance shall be measured while the resistors are in the oven. (b) Salt-Water bath. The salt-water baths specified herein shall contain common table salt. The baths shall be of sufficient volume to maintain relatively constant temperature for the duration of the tests. (e) First days cyclin

24、g. Resistors shall be placed in a dry oven maintained at a temperature of 85C -t- 2C. Rated de voltage shall be applied for 1 hour. Immediately after removal of this potential, the resistance shall be measured while the resistors are in the oven. Upon completion of these measurements, the rated de v

25、oltage shall again be applied for 1 hour with the resistors in the oven maintained at 85“ -t- 2C. Within 5 seconds after removal of this potential, resistors shall be taken from the oven and immersed for a period of 1 hour in a saturated salt-water bath maintained at 85“ + 2C. Within 5 seconds after

26、 removal from this bath, resistors shall be immersed for a period of 1 hour in another saturated salt-water bath maintained at O“ + 2, - 0C. Resistors shall then be thor- oughly and quickIy washed in tap water and al1 surfaces wiped or air-blasted clean and dry. The resistors shall again be placed i

27、n the oven maintained at a temqerature of 85“ + 2C and operated at rated de potential for 1 hour. After removal of this potential and resistors have stabilized at 85“ f 2“C, the resistance shall be measured while the resistors are in the oven. (d) Conditioning between daily cycles. After each days f

28、inal cycle, resistors shall be left overnight in the oven maintained at 85“ -t- 2“C, with no voltage appIied. In no case shall this conditioning period exceed 24 hours. (e) Subsequent cycling. Rated de voltage shall be applied for 1 hour to the resistors while they are in the oven maintained at 85“

29、to zk 2C. Within 5 seconds after removal of this potential, resistors shall be taken from the oven and immersed for a period of 1 hour in a saturated salt-water bath maintained at 85“ -t- 2OC. Within 5 seconds after removal from this bath, resistors shall be immersed for a period of 1 hour in anothe

30、r saturated salt-water bath maintained at O“ + 2, - 0C. Resistors shall then be thoroughly and quickly washed in tap water and all surfaces wiped or air-blasted clean and dry. The resistors shall again be placed in an oven maintained at a temperature of 85“ one group shall be subjected to load and t

31、he other group to polarization. (e) Load. During steps 1 and 4, rated (100%) wattage or maximum rated voltage, whichever is smaller, shall .be applied for the first 2 hours of each step. (f) Polarization. During steps 1 to 6 inclusive, a 100-volt d.c. potential shall be applied to the three remainin

32、g units with positive connected to the resistance element, and negative connected to the mounting plate. (8) Subcycle. During step 7, at least 1 hour but not more than 4 hours after step 7 begins, the resistors shall be removed from the humidity chamber in order to perform step “a, after which the r

33、esistors shall be returned to the humidity chamber and kept there until the next cycle begins. (h) Number of cycles. Resistors shall be subjected to 10 continuous cycles, each cycle as shown on Figure 1 of latest issue EIA Standard RS-186. (j) Final measurements. Upon completion of step 6 of the fin

34、al cycle, the resistors shall be held at the high humidity condition at 25 f 2C for a period of 11/2 to 31/2 hours, after which the resistance shall again be measured as specified in step c. NOTE : Final insulation resistance measurements to be made at room temperature outside the box within 10 minu

35、tes after removal, (k) As a result of the resistors being tested as specified above, resistors shall show no evidence of breaking, cracking, spalling, or loosening of terminals or mounting hardware. The initial insulation resistance shall not be less than 500 megohms. The final insulation resist- an

36、ce shall be not less than 100 megohms. The d.c. resistance shall not change more than 1.0% between the initial and final measurements, 4.2.9 Dielectric Strength (a) Resistors shall be tested in accordance with latest issue EIA Standard RS-186, Method 4, Dielectric Test. (b) Mounting. Resistors shall

37、 be mounted on a conductive material which will conform to the resistor surface so that at least 90% of the outer periphery is contacted, (c) Procedure. An a.c. potential of 500 volts shall be applied for 1 minute between the resistor terminals, connected together, and the conductive material. (d) A

38、s a result of the test specified above, there shall be no flash over, evidence of breakdown of insulation, or change in resistance in excess of 0.05%. 4.2.10 Terminal Strength (a) Axial wire lead terminal resistors. Resistors shall be firmly clamped and a pull of 5 pounds shall be applied to each te

39、rminal, one at a time, in a direction along the horizontal axis of the resistor. After the pull has been removed, all terminals shall be bent through 90“ at a point %jf from the body of the resistor, with the radius of curvature at the bend approxi- EIA 227-A b5 m 3234b00 0063427 3 m mately 1/32“. T

40、he terminals shall be clamped at a point s/c4 f from the bend on the side between the bend and the remaining portion of the lead away from the body. The body of the resistor shall then be rotated about the original axis of the bent terminal through 360“ in alternating directions for five such 360“ r

41、otations at the rate of approxi- mately 5 seconds per rotation. After this test, the resistors shall be examined for evidence of damage and tested for continuity. (b) Wire-lead terminals. Wire-lead terminals shall not break when twisted or pulled as speci- fied above. (c) The terminals shall be secu

42、rely fastened to the form so as to resist the pull and twist specified without damage. The resistance element shall be securely connected mechani- cally and electrically to the terminals in such a manner that the normal movement of the terminals shall not result in strain, wear, or damage to the ele

43、ment, coating, or enclosure. 4.2.11 Vibration (a) After the measurement of resistance the resistor shall be subjected to vibration accord- ing to Method 204 of Mil-STD-202, Test Condition D. The resistors shall be rigidly mounted on appropriate jig fixtures with their bodies re- strained from moveme

44、nt and their leads supported at a distance %“ from the resistor body. These fixtures shall be constructed in a manner to insure that the points of the resistor-mounting support will remain in static condition with reference to the vibration table. During vibration each resistor shall be monitored to

45、 determine electrical discontinuity by a method that shall at least be sensitive enough to monitor or register, automatically, any electrical discontinuity of 0.1 millisecond or greater duration. Test leads used during this test shall be no larger than AWG size 22 stranded wire. The resistors shall

46、be vibrated in each of three mutually perpendicular planes ; the initial plane shall pass through the resistor axis and terminals, and the other two planes shall be mutually perpendicular. (b) Upon completion of the vibration test, units shall be tested for resistance. The resistance shall not chang

47、e more than 0.1% and there shall be no mechanical damage. 4.2.12 Temperature Coeflcient of Resistance (a) The resistors shall be maintained for 30 to 45 minutes within 3“ at each of the following ambient temperatures: *25O, 145“, *25“, and -55“ consecutively. At the end of each period, the resistanc

48、e shall be measured again, at the temperature maintained during the period. The temperature coefficient of resistance, referred to a reference temperature of 25C shall then be computed as follows : AR X 100 TC = R X At Where : TC = Temperature coefficient in percent per degrees C. R = Resistance at

49、reference temperature. A R = Change in resistance at test temperature from resistance at reference temperature. A t = Difference between test and reference temperature in degrees. *This temperature shall be considered the reference temperature for the succeeding extreme temperature. (b) As a result of the test specified above, the temperature coefficient of resistance of the resistors, referred to an ambient temperature of 25“C, shall not exceed the applicable value specified in paragraph 2.4. EIA 229-A b5 3234b00 0063430 T i s- RS-229-A Page 9 O 4.2.13 Load Life (a