1、-z. i; - - / EIA 322 b5 m 3234600 0065555 7 m USAS cy cy Cu) m 4 I 9 Y Wire- Wound Power-Type Rheostats C8 3.1 3-1 9 6 8 Approved July 24, 1968 USA STANDARDS INSTITUTE RS-322 (Revision of TR-133) October 1965 Engineering Department ELECTRONIC INDUSTRIES ASSOCIATION r EIA 322 65 m 3234600 0065556 9 m
2、 # 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 minimum delay the pro
3、per 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 not their adop- tion m
4、ay 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 obiigation whatever to parties adopting the recommended standards. Published by ELECTRON IC INDUSTRIES ASSOCIATION Engineering Department
5、2001 Eye treet, N.W., Washington, D. C. 20006 Q Electronic Industria STYLE RRP 06 r 0.688 2 0.063 7 MOUNTING SURFACE -1 -+0.875? 0.031 DIA ,125 DIA HOLE STA N DAR D BUSH I N G 0.125 +0.001 DIA DESIGN AND POSITION OF TERMINALS OPTIONAL I , LIUSHING $-32 UNEF-2A NUMBER, POSITION, AND DIMENSIONS OF SLO
6、TS OPTIONAL 0.125 +0.001 DIA UNTING SURFACE ( . ) k+-0.500 20.047 ANGLE OF MECHANICAL ROTATION 290 TO 305 -1 “%?Y OF 0.78 I i 0.063 ANY TERMINAL MAX X 45 SLOTTED SHAFT 0.031 4 0.005 0.047 2 0.005 ALL DIMENSIONS IN INCHES SEE TABLE IV FOR SHAFT LENGTHS EIA 322 65 M 3234600 0065558 2 Style RS-322 Page
7、 2 Angle of Rotation Mechanical 1 A 1 B I C I D 2. RHEOSTATS, UNENCLOSED, 25 WATTS TO 150 WATTS INCLUSIVE; STYLES RRP 10, RRP 15, RRP 20, RRP 25, AND RRP 30 RRP 10 RRP 16 RRP 20 RRP 25 TO FIT IN 0.188 TER M I NA LS O PT I ON AL 275“to 305“ 1.68 1.42 1.88 1.41 295“ to 310“ 2.00 2.50 1.44 295“ to 310“
8、 1.82 2.56 1.78 295“ to315“ 3.19 2.19 2.69 1.78 0.500 k0.015 LOCKING BUSHING RRP 30 290“ to315“ ,NUMBER, POSITION,AND DIMENSIONS OF SLOTS OPT ION AL 4.06 2.44 3.00 2.03 L0.250 DIA I-! -2-32 UNEF-2A MOUNTING SUR FACE FLATTED SHAFT 7 0.216 k0.005 MAX X 45O 32 Y 4 L0.047i0.005 0.063 + 0.015 SHAFT ALL D
9、IMENSIONS IN INCHES SEE TABLE IV FOR SHAFT LENGTHS E 0.080 0.138 0.167 0.167 0.167 Watts 100 - EIA 322 65 m 3234600 00b5559 4 m RS-322 Page 3 StyJe CD MAX- Angle of Rotation Mechanical I A 1 B I C 1 D I E Watts 1 RRP 55 3. RHEOSTATS, UNENCLOSED, OVER 150 WATTS; STYLES RRP 35, RRP 40, RRP 50, AND RRP
10、 55 330“ to 340“ 12.31 6.75 3.69 3.03 3.00 f 1/32 1,000 MOUNTING SURFACE f 0.375 DIA ! I-20 UNC-26 4 O. I67 1 MAX 4 LTO OUTER EXTREM I TY OF ANY LDESIGN AND POSITION OF TERMINALS OPTIONAL TERMANAL 0.344 f. 0.005 # FLATTED SHAFT ALL DIMENSIONS IN INCHES = STYLE RRP 06 J ON $R AND TO FIT IN 0.125 DIA
11、HOLE -32 THD STANDARD BUSHING 4 ANGLE OF MECHANICAL ROTATION 295 TO 305 LOCKING BUSHING NUMBER, POSITION, AND DIMENSIONS OF SLOTS OPTIONAL 0.125t 0.001 DIA 1 -0.515 MAX 0.032 X 0.085 I SLOTS S LOTTE D q/-+-$ MAX X 45 SHAFT 7 bqo.o?m5 0.047 k 0.005 ALL DIMENSIONS IN INCHES SEE TABLE IV FOR SHAFT LENG
12、THS +O -2 EIA 322 65 m 3234600 00b55bL 2 m RS-322 Page 5 2. RHEOSTATS, ENCLOSED, 10 WATTS; STYLE RRP 07 -1.047i 0.047 DIA DESIGN AND POSITION OF TERM INALS OPTIONAL 0.125 DIA HOLE DIMENSIONS 0.250i0.015 LTO FIT IN LOCKING BUSHING NUMBER, POSITION, AND DIMENSIONS OF SLOTS MOUNTING SURFACE SLOTTED SHA
13、FT A k L0.031 f0.005 0.047 ? 0.005 ALL DIMENSIONS IN INCHES SEE TABLE IV FOR SHAFT LENGTHS ANGLE OF MECHANICAL ROTATION 290 TO 305O EIA 322 65 W 3234600 O065562 4 W Style I RS-322 Page 6 Angle of Rotation Mechanical 1 A 1 Watts1 3. RHEOSTATS, ENCLOSED, 18 AND 25 WATTS; STYLES RRP 11 AND RRP 16 MOUNT
14、1 NG H-0.500?r0.015 II f SURFACE NDARD BUSHING -#8-32 UNC-2A Xi MACHINE SCREW REGULAR SPRING OR INTERNAL- TOOTH LOCK WASH ER 1. DESIGN AND POSITION OF TERMINALS OPITIONAL 0.500 f0.015 o - LOCKING BUSHING NUM BER, POS IT ION, AND DIMENSIONS OF SLOTS OPTIONAL 1 Lt-32 UNEF-2A MOUNTING SURFACE -A MAX DI
15、A _I TO FIT IN 0.188 DIA HOLE I r 0.2 I6 ? 0.005 I MAX X 45* SLOTTED 0.047 iz I . 2 . . . 21/2 I * 6 . . . 1% . Standard Bushing In. -t 3/G4 % 743 1% 2% . . 2 . . I. Shaft Lacking Bushing- In. movement of the contact arm shall not result in a resistance change greater than 10 percent; the total resi
16、stance shall not change in excess of 2 percent, and there shall be no evidence of mechanical damage. S. Acceleration (Applicable only to Styles RRPO5, RRPOG and RRPO7) Mount units as for shock test. The rheostats should withstand a constant acceleration of 50 Gs for a period of 5 seconds in each of
17、the positions. There shall be no open circuit or intermittent contact, movement of the contact arm shall not result in a resistance change greater than 10 percent; the total resistance shall not change in excess of 2 percent, and there shall be no evidence of mechanical damage. T. Vibration, Low Fre
18、quency (Applicable to Styles RRPO5 thru RRP3O only.) Units should be mounted with the contact arm set at approximately 50% of the effective rotation. Locking-bushing type resistors shall have the locking nut tightened with a torque not greater than 8 1b.-in. The units shall be subjected to a simple
19、harmonic motion having an amplitude of 0.03 inch, (0.06 inch maximum total excursion), the frequency being varied uniformly between the approxi- mate limits of 10 and 55 cycles per second (cps.) . The entire frequency range, from 10 to 56 cps. and return to 10 cps., shall be traversed in ap- proxima
20、tely one minute. This motion shall be applied for a period of two hours in each of three mutually perpendicular directions (total of six hours). There shall be no evidence of intermittent contacts or electrical discontinuity. The total resistance shall not change in excess of 5%. The contact arm sha
21、ll not move more than 2“, nor shall there be a change in resistance between the contact-arm terminai and either end terminal in excess of 5%. There shall be no evidence of mechanical damage. U. Vibration, High Frequency (Applicable only to Styles RRP05, RRPOG, and RRP07.) Mount as for low frequency
22、vibration test. The specimens shall be subjected to a simple harmonic motion having an amplitude of either 0.06 inch double amplitude (maximum total excursion) or 15 G, whichever is less, the frequency being varied logarithmically, between the approximate limits of 10 and 2000 cps. The entire freque
23、ncy range, from 10 to 2000 cps. and return to 10 cps. shall be traversed in 20 minutes. This cycle shall be performed 12 times in each of three mutually per- pendicular directions, (total of 36 times), so that the motion shall be applied for a total period of approximately 12 hours. There shall be n
24、o open circuit or intermittent contact, movement of the contact arm shall not result in a resistance change greater than 10 percent; the total resistance shall not change in excess of 2 percent, and there shall be no evidence of mechanical damage. 0 SECTION VI - APPLICATION NOTES AND DEFINITIONS A.
25、Application and Engineering Data 1. Standard Derating It is customary to use rheostats at not more than 75% of their nominal wattage when mounted on a standard steel panel (see SECTION V., Paragraph L) in still air and reason- ably free space at an ambient temperature of 85OC. Y - EIA 322 65 m 32346
26、00 0065572 7 m RS-322 Page 16 2. Additional Derating When rheostats are mounted in restricted enclosures which limit ventilation, or when mounted on a non-metallic panel, the input wattage should be reduced still further so that the maximum operating temperature will not be exceeded. In the absence
27、of specific measurements of Oper- ating temperature, a reduction in input power to 50% of the nominal rated wattage is cus- tomarily followed in good engineering practice. 3. Of-Position Care should be exercised in specifying an “off” position on rheostats when they are required to break direct-curr
28、ent circuits having potentials high enough to cause arcing. 4. Rhe0stat.e Should not be used at potentials above ground greater than 500 volts (250 volts for rheostat styles RRPO5, RRPOG, and RRPO7) unless supplementary insulation is provided. B. Definitions and Test Conditions 1. Still Air Still ai
29、r is surrounding air with no circulation other than that created by the heat of the rheostat being operated. 2. HotSpot The hot spot is the point or elemental area of maximum temperature adjacent to the exposed surface of the resistance winding. 3. Thermal Stability Thermal stability has been reache
30、d when no further change in temperature is observed be- tween two successive measurements taken at five minute intervals, other conditions remaining constant. 4. Nonturn Device A nonturn device is a projection on the rheostat assembly to prevent its rotation with respect to the surface on which it i
31、s mounted. 5. Total Mechanical Rotation The total mechanical rotation of the operating knob of a rheostat is the total angular dis- placement between fixed stop points. 6. Eaective Rotation The effective rotation is the angular displacement of the operating end of the shaft which is effective in pro
32、ducing useful change of resistance. 7. Left Terminal The left terminal of a rheostat is that terminal to which the contact is adjacent when the operating end of the shaft of the rheostat is turned as far as possible in a counterclockwise direction when viewed from the operating end with terminals do
33、wn. - - - - IA 322 65 m 3234600 0065573 9 m RS-322 Page 17 8. Right Terminal The right terminal of a rheostat is that terminal to which the contact is adjacent when the operating knob of the rheostat is turned as far as possible in a clockwise direction when facing the operating end of the shaft wit
34、h terminals down. 9. Percent of Standard Total Mechanical Rotation The percent of standard total mechanical rotation is determined from the angular position of the contact member measured from the fixed stop at the left terminal. 10. The total resistance of a rheostat with an off position is the res
35、istance between its active terminals when the movable contact is at the end of the total resistance. Total Resistance of a Rheostat with an O# Position 11. Total Resistance of a Rheostat without an O# Position The total resistance of a rheostat without an off position is the resistance between the e
36、nd terminals when the movable contact is against the stop at the end of the total resistance. 12. Center Resistance The center resistance of a linear wound rheostat is the resistance between the center ter- minal and the desired end terminal of the rheostat when the movable contact is located at 60%
37、 of the effective rotation. 13. Linear Resistor A linear resistor is one having a nominally constant rate of change of resistance with angu- lar rotation. 14. Minimum Current Minimum current is the current passing through a rheostat when the entire resistance ele- ment is in use. 15. Maximum Current
38、 Maximum current is the current passing through a rheostat when the rheostat is at a minimum resistance setting. 16. Methods and Precautiom The bridge method shall be used for the measurement of resistance. 17. Nominal Maximum Current-Rating The nominal maximum current rating shall be determined in
39、the case of linear wound rheo- stats, by dividing the nominal wattage rating by the resistance value of the unit and taking the square root of the quotient. C. Compliance with Teste and Specifications 1. The sample scheme or percentage of any shipment which shall be subjected to tests outlined in th
40、e specification is a matter for determination between the Vendor and Purchaser. 2. The following tests are recommended for application as incoming material inspection tests on a 100% basis: a. Resistance. b. Conformance with mechanical dimensione. c. Dielectric Strength. 3. The following supplementary test is recommended for quality control : a a. Torque.
