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1、Standard AEROSPACE EQUIPMENT VOLTAGE and FREQUENCY RATINGS Authorized licensed use limited to: IEEE Xplore. Downloaded on December 25,2010 at 10:15:16 UTC from IEEE Xplore. Restrictions apply. PREFACE It has been widely recognized that there is a distinct need ior preferred voltage and irequency rat
2、ings for aerospace electric apparatus, which will be generally acceptable to manufacturers and users, to serve as a basis for voltage and frequency standards for aerospace systems and equipment. Many difficulties and niuch confusion will be elimi- nated by adopting suitable standard voltage and fre-
3、 quency ratings for all aerospace electric equipment. These standard voltages and frequencies should then be made a part of specifications and nameplates marked accordingly. :pparatus should be designed for satis- factory operation over the voltage and frequency ranges giren in the tables, but with
4、performance not necessarily the same as guaranteed at rated voltage and irequency. Performance data and acceptance tests should he on the basis of standard voltages and fre- quencies. It is recognized that special applications may require operation over other voltage and frequency ranges than those
5、shown as standard. Standardization of voltage ratings for aerospace elec- tric accessories is especially difficult because of the close margins for application of aerospace equipment. Ihe nominal designations used to identify various sys- tems have in the past been the subject of controversy, but co
6、iiimon usage in the aircraft industry and the riiilitarj- aviation services supports the 14- and 28-volt designations for systems using 6- and I?-cell lead-plate storage batteries. Vith present large electric systems, the battery has become .I relatively small part of the total source ca- pacity. it
7、11 the widespread use of plug-in power facilities at airline terminals and military bases, opera- tion iron1 battery power seldom occurs. .Ithough the battery may rcpresent only a small portion oi the available system capacity, its limitations determine the direct-current voltages which must be used
8、. Direct-current system voltage must be high cnough to maintain the battery in a charged condition, but not high enough to cause excessive battery heating. Twenty-eight volt systems are usually operated at be- tween 27 and 28.5 volts at the point of regulation, and this accounts for the choice of 28
9、 as the noniinal direct- current system voltage. Voltage is adjusted by setting the regulators of the generators, or the alternating- current to direct-current conversion equipment, and the particular value chosen is at least partially dependent on operating conditions. Direct-current generators mus
10、t be capable of 30 volts output over the specified speed range to allow for voltage drops totaling 1% volts minimum (including the voltage drop in the par- alleling resistors, when used) between each generator and its regulated point. To obtain minimum weight, system wiring is de- liberately loaded
11、heavily and allowance niust be made for voltage drop between the regulated point and the electric accessories. Best weight economy dictates the use of more heavily loaded cable for intermittent loads than for continuous loads. Rated direct-current volt- age has been selected as 27 volts for continuo
12、us-duty devices and as 26 volts for intermittent-duty devices. Accessories such as engine-starter motors must be capable of operation when the battery is the sole source of power. They must also operate after one or more generators have been paralleled with the battery, and in most cases they must b
13、e suitable for operation from 30-volt starter trucks. Starters, in particular, require very heavy currents and are designed to operate at voltages of the order of 12 volts at the terminals when drawing power from a 24-volt battery. It does not ap- pear possible to set up standard voltages for starte
14、rs and items operated during starting, as restrictive values would involve weight penalties vhich would be unacceptable to the users. The steady-state voltage extrenie limits (all toler- ances additive in the same direction siiiiultsneously) of the present state of the art of generation system manu-
15、 facture is considered excessive. These limits necessi- tate undesirable design penalties (weight, complexity, cost) in power utilization equipment. Electric genera- 3 Authorized licensed use limited to: IEEE Xplore. Downloaded on December 25,2010 at 10:15:16 UTC from IEEE Xplore. Restrictions apply
16、. tion equipment manufacturers should make every rea- sonable effort to improve the state of the art so that the steady-state alternating-current voltage extremes of any phase will be within 2 3 percent of nominal at the point of regulation. This includes voltage change due to regulator adjustment e
17、rror (field level), en- vironnient, speed range, no-load to full-load range, load unbalance between any two phases up to 30 percent of average total load, all at power factors from 1 to 0.75 lag. Designers and detail specification writers need to consider also the following generation system charac-
18、 teristics (reference MIL-STD-704) not defined in I E E E 127: (a) overvoltage versus time protection limits (b) undervoltage versus time protection limits (c) under-frequency-voltage limits (d) low-frequency and high-frequency voltage transients (primarily due to load and control switching). The ba
19、sic purpose of I E E E 127 is to serve as a guide to show preferred (steady-state) frequency and voltage ratings for primary power systems. A careful study, including the pertinent factors noted above, was accom- plished by the Flight Vehicle Systems Integration Sub- committee. The attached tabulati
20、on gives recom- mended standard frequencies and voltages for all types of aerospace electric apparatus for which standards ap- pear practical. The original draft of this revision to A I E E 700 was prepared by the following panel members under an assignment given by A I E E Flight Vehicle Electric S
21、ystem Subcommittee Chairman, T. B. Owen: B. F. Varney, Chairman P. Duyan P. Frankel W. R. Marker S. W. Silverman R. E ( . Walter J. P. Dallas The I E E E Standards Committee takes this occasion to draw attention to the value of suggestions based upon experience gained in the application of the Stand
22、- ards to general practice. Any suggestions looking toward improvement in the Standards will be wel- comed for the guidance of the committee in prepara- tion of future editions, and should be communicated to the Secretary of the I E E E Standards Committee, Box A, Lenox Hill Station, New York 21, Ne
23、w York. A A 4 Authorized licensed use limited to: IEEE Xplore. Downloaded on December 25,2010 at 10:15:16 UTC from IEEE Xplore. Restrictions apply. AEROSPACE EQUIPMENT STEADY-STATE VOLTAGE RATINGS (Direct Current) Soniinal System Designation (volts) 14 Generators Rated -oltages . 15 tor rated voltag
24、e). +O to -15% I-oltage .Adjustment Range (Based on genera- *Continuous Duty Devices Rated Voltages . Voltage Range . *Intermittent Duty Dex-ices Rated Voltages . ;oltage Range . *Battery-Operated Devices (Devices which must operate xvith or without the generator supplying power). Rated Voltages . i
25、oltage Range . *Dielectric Tests (RMS -olts for 1 minute at 60 cycles or 120 percent of value shown for 5 sec- onds) Factory Test Volts *Field Test or Retest before and after use (CLEAN (75% of Factory Test Volts). and DRY only) 13 2 10% 12.5 * 10% 11.5 225% 1500 1125 28 30 t o to -15% 27 -tlO% 26 2
26、10% 23 *25% 1500 1125 120 125 Oto- 5% 115 5 10% 115* 210% 1500 1125 .4pparatus is to uiiction satisfactorily over tile voltage ranges given. but with periot-tate not necessarily in accordance with guarantees at rated voltage. *For operation from a voltane-reaulated sptem. If operation i5 required fr
27、om battery alone, use values for “battery operated devices”. It is assumed that most Ilj-volt wirinx will he applied on the basis of thermal rating. and prorislons for wider toler- Devices such as starters, et cetcra, and items operated during starting, must operate under conditions of much wider *I
28、n accordance with recommendations of AIEE No. 803 (now IEEE No. 135) Proposed Test Code for Aircraft f f ances for voltage regulation on intermittent loads has not been made. +*I voltage ranges. These devices are not covered by these Standards. Equipment Electrical Insulation, dated July 1957. 5 Aut
29、horized licensed use limited to: IEEE Xplore. Downloaded on December 25,2010 at 10:15:16 UTC from IEEE Xplore. Restrictions apply. AEROSPACE EQUIPMENT STEADY-STATE FREQUENCY RATINGS (Alternating Current) Sominal System Frequency (cycles per second). . 400 2000 3200 Type I -Standard 25% 25% 25% Type
30、11 -Optimum . 21% 2 1 % 21% Type 111-Precision 20.01% 20.01% 20.01 70 Type I-Broad . 225% 225% *25% Type I Standard Frequency is in accordance with Y IL-STD-704. Military Standard. Electrir Power, Aircraft. Characteristics and Utilization of. dated 6 October 1959. Optimum Frequency represents curren
31、t state of the art capability. Precision Frequency represents close tolerance power for systems with high accuracy requirements which cannot be met using power with wider frequency tolerances. Broad Frequency represents an alternating-current generating system with broad fre- quency tolerances such
32、as results from direct, or simple. coupling of an alternating- current generator to a prime mover which is not regulated for frequency control. Type I1 Type I11 Type IV lrnless otherwise stipulated, Type I Standard Frequency is assumed to be applicable. AEROSPACE EQUIPMENT STEADY-STATE VOLTAGE RATIN
33、GS (Alternating Current) Sominal Sptem Designation (volts). . 115 1 15/200 Generators Rated Voltages . 120 120/208 Adjustment Range . 115 2 5% 115/2OO 2 5% Continuous Duty Devices Rated Voltages . 115 1 15/200 Voltage Range . 5% 5% Intermittent Duty Devices Rated Voltages . 115 1 15/200 Voltage Rang
34、e . +5 to -10% +5 to -10% Emergency Duty Devices Rated Voltages . 115 11 j/ZOO Voltage Range . +5 to-lj% +5 to-Ijj% *Dielectric Tests (RMS Volts for 1 minute at 60 cycles or 120 percent of value shown for 5 sec- onds) Factory Test Volts 1500 1500 *Field Test or Retest before and after use (CLEAN and
35、 DRY only) (75% of Factory Test Volts). 1125 1125 230/400 .Apparatus is to function satisfactorily over the voltage and frequency ranges given (simultaneously). but with performance not necessarily in accordance with guarantees at rated voltage. I n accordance with recommendations of AIEE So. 803 (n
36、ow IEEE So. 135) Proposed Test Code for Aircraft Equip- ment Electrical Insulation, dated July 1957. 6 240/4 16 230/400 2 5% 230/400 25% 230/400 +5 to -10% 230/400 + j to-lj% 1800 1260 Authorized licensed use limited to: IEEE Xplore. Downloaded on December 25,2010 at 10:15:16 UTC from IEEE Xplore. Restrictions apply.