ECA 172-B-1975 Fixed Composition Resistors ( BEST AVAILABLE COPY )《固定合成电阻》.pdf
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1、CQ I ,. I fn a: cc iiJ ANSI C83.48-1974 Approved November 15, 1974 AMERICAN NATIONAL STANDARDS INSTITUTE EIA STANDARD Fixed Composition Resistors RS172-B (Revision of RS172A) MARCH 1975 Engineering Deportment ELECTRONIC INDUSTRIES ASSOCIATION NOTICE EIA engineering standards are designed to serve th
2、e J?.Ublic interest through eliminting mis understandings between manufacturers and purchasers, facllitating interchangeability and improve ment of products, and assisting the purchaser in selecting and obtaining with minimum delay the proper product for his particular need. Existence. of such stand
3、ards shall not in any respect pre clude any member or non-member of EIA from manu“facturing or selling products not conforming to such standards, nor shall the existence of such standards preclude their voluntary use by those otber than EIA members whether the standard is to be used either domestica
4、lly or internationally. ecommended standards are adopted by EIA without regard to whether or not their adoption may 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 adopt
5、ing the recommended standards. Published by ELECTRONIC INDUSTRIES ASSOCIATION Engineering Department 2001 Eye Street, N.W., Washington, D. C. 20006 0 Electronic Industries Association 1975 All rights reserved Printed In U.S.A. FIXED COMPOSITION RESISTORS (From EIA Standard RS-172 and Standards Propo
6、sal No. 1164, formulated under the cognizance of EIA Working Group P-1.1 on Fixed Components) 1. SCOPE 1,1 This standard covers insulated, fixed resistors having a composition resistance element and !lapable of full load operation at an ambient temperature of 70C. This standar describes minimuUl lim
7、its of performance commonly -ubserved in commercially available produody of the resistor does not extend beyond the extremeties of the block. The resistor leads shall he so positioned that the distance between the resistor leads and the V-hlock shall be not less than the radius of the resistor minus
8、 the radius of the lead wire. 3.2.5.2 Procedure- The rms voltage at commercial line frequency not exceeding 100Hz specified in Table VII shall be applied to the resistors for 5 seconds between the resistor terminals connected together and the V -block at atmospheric pressure. TABLE VII DIELECTRIC WI
9、THSTANDING VOLTAGE Resistor Wattage RMS Volts 1/8 300 1/4 500 1/2 700 1 1000 2 1000 RS-172-B Page10 3.2.6 Short Time Overload (see 2.8)- Following a measurement of resistance, a potential of 2.S :X the rated continuous working voltage (see 2.3) shall be applied for S seconds. In no case shall the vo
10、ltage exceed the applicable value listed in Table VIIi. Resistance shall be measured 30 minutes after removal of the test potential. -CAUTION: Test potential shall he established by use of a dummy load to avoid excess stress on the test specimens. TABLE VUI MAXIMUM OVERLOAD VOLTAGE Power Rating Maxi
11、mum Voltage Watts (de or peak ac) Volts 1/8 200 1/4 400 1/2 700 1 1000 2 1000 3:2.7 Low Temperature Operation (see 2.9)- Following the resistance measurement, resistors shall be placed in a cold chamber maintained at a temperature of -65C + 0C -SC; After 1 hour of stabilization at this temperature,
12、full rated working voltage, as specified in 2.3, shall he applied for 4S minutes. Resistors may-he loaded individually or in parallel. 1S +S -0 minutes after the removal of voltage, the specimens shall be removed from the chamber and maintained at a temperature of 2SC SC for a period of 24 hours, af
13、ter which resistance measurements shall again he made. 3. 2. 8 Temperature Cycling (see 2.1 0) 3.2.8.1 Mounting- Resistors shall he_ mounted by their terminals so that there shall be at least 1“ of free airspace around each resistor, and with the mounting in such a position with respect to the air s
14、tream that it offers substantially no obstruction to the flow of air across and around the resistors. 3.2.8.2 Procedure- Resistors shall be subjected to the temperature cycle shown in RS-172-B Page 11 Table IX for a total of 5 cycles performed continuously. The air temperature shall he mered by a su
15、itable means and as near the center of the group of resistors as possible. If a thermometer is used, it shall be mounted parallel to the axis of the resistor. The temperature shall be maintained at each of the extreme temperatures by means of circulat ing air. The hot and cold chamber shall be of su
16、ch capacity that the air at the resistors will reach the temperature specified in Table IX within 2 minutes after the resistors have been transferred to the appropriate chamber. Resistors shall not he subjected to circulat ing air for the 10 to 15 minute periods at room temperature (25 5C). Measurem
17、ents of resistance shall he made before the first cycle and within 24 hours after the fifth cycle. . TABLE IX TEMPERATURE CYCLE Sequenc Temperature Time oc Minutes Start at +25 S 10 to IS Reduce to -55 +0. -3 30 Return to +25 5 10 to IS Raise to +85, +3, -0 30 Return to +25 5 10 to 15 3.2.9 Humidity
18、 (see 2.11),- Following measurement of resistance in a dry atmosphere of 25C .5C, resistors shall he placed in an atmosphere of 40C 2C and 90% to 100% . relative humidity for 240 8 hours. Resistors shall he removed at the end of this period, air dried for 1 hour 15 minutes, and final resistance meas
19、ured. 3.2.10 Load Life (see 2.12) 3.2.10.1 Test Conditions- This test shall he conducted at an ambient temperature of 70C 5C. Resistors shall be mounted and soldered or clipped to terminals. The effective length of each lead shall be 1 “ 3/16 ! Resistors shall he so arranged that the temperature of
20、any one resistor will not appreciably influence the temperature of any other resistor. There shall he no circulation of air directly over the resistors other than that caused by the heat of the resistors. The voltage used shall he the rated continuous working voltage specified in 2.3. Adequate preca
21、utions shall be taken to maintain con stant voltage on resistors under test. RS-172-B Pagcd.2 3.2.11 Terminal Strength (see 2.13) 3.2.11.1 Measurements- Resistance shan be meill!ured-before the testing specified in 3.2.11.2 and after the testing specified in 3.2.11.3. 3.2.11.2 Direct Load- Resistors
22、 shall be held by one terminal and the load shall be gradually applied in the direction of the longitudinal axis of the re:istor until the applied load reaches 5 pounds for all styles except RRC05. Applied load shall be 2 pounds for style RRCOS. The applied load shall be maintained for S seconds. 3.
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