602:, to a predetermined distortion level, variable per manufacturer or per product line. Driving an amplifier to 1% distortion levels will yield a higher rating than driving it to 0.01% distortion levels. Similarly, testing an amplifier at a single mid-range frequency, or testing just one channel of a two-channel amplifier, will yield a higher rating than if it is tested throughout its intended frequency range with both channels working. Manufacturers can use these methods to market amplifiers whose published maximum power output includes some amount of clipping in order to show higher numbers.
82:
549:, which is a multiplier that, when applied to the rated output power, gives the power level a motor can sustain for shorter periods of time. The service factor is typically in the 1.15-1.4 range, with the figure being lower for higher-power motors. For every hour of operation at the service-factor-adjusted power rating, a motor loses two to three hours of life at nominal power, i.e. its
576:
temperatures and deterioration of insulation, may be considered an acceptable trade-off in emergency situations. The power rating of switching devices varies depending on the circuit voltage as well as the current. In certain aerospace or military applications, a device may carry a much higher rating than would be accepted in devices intended to operate for long service life.
492:), there may even be two power ratings, a maximum (peak) power rating and an average power rating. For such devices, the peak power rating usually specifies the low frequency or pulse energy, while the average power rating limits high-frequency operation. Average power calculation rating depends on some assumptions about how the device is going to be used. For example, the
429:
sum of output power and losses. In some types of equipment, it is possible to measure or calculate losses directly. This allows efficiency to be calculated with greater precision than the quotient of input power over output power, where relatively small measurement uncertainty will greatly affect the resulting calculated efficiency.
428:
Equipment is generally rated by the power it will deliver, for example, at the shaft of an electric or hydraulic motor. The power input to the equipment will be greater owing to the less than 100% efficiency of the device. Efficiency of a device is often defined as the ratio of output power to the
627:
The nominal power of a photovoltaic module is determined by measuring current and voltage while varying resistance under defined illumination. The conditions are specified in standards such as IEC 61215, IEC 61646 and UL 1703; specifically, the light intensity is 1000 W/m, with a spectrum
575:
Power ratings for electrical apparatus and transmission lines are a function of the duration of the proposed load and the ambient temperature; a transmission line or transformer, for example, can carry significantly more load in cold weather than in hot weather. Momentary overloads, causing high
62:
Power rating limits are usually set as a guideline by the manufacturers, protecting the equipment, and simplifying the design of larger systems, by providing a level of operation under which the equipment will not be damaged while allowing for a certain safety margin.
511:) is defined as the maximum output (MW) that an electric power generating station is capable of producing continuously under normal conditions over a year. Under ideal conditions, the actual output could be higher than the MCR.
613:(EIA) rating system, however, determines amplifier power by measuring a single channel at 1,000 Hz, with a 1% distortion level—1% clipping. Using the EIA method rates an amplifier 10 to 20% higher than the FTC method.
166:
devices, particularly speakers, it is to prevent mechanical damage. When heat is the limiting factor, the power rating is easily calculated. First, the amount of heat that can be safely dissipated by the device,
449:, the power rating almost always refers to the maximum power flow through the device, not dissipation within it. The usual reason for the limit is heat, and the maximum heat dissipation is calculated as above.
415:
572:, irreparable damage can occur very quickly. Exceeding the power rating of most devices for a very short period of time is not harmful, although doing so regularly can sometimes cause cumulative damage.
526:) which is 85% of the 90% of MCR. The 90% MCR is usually the contractual output for which the propeller is designed. Thus, the usual output at which ships are operated is around 75% to 77% of MCR.
609:(FTC) established an amplifier rating system in which the device is tested with both channels driven throughout its advertised frequency range, at no more than its published distortion level. The
568:
Exceeding the power rating of a device by more than the margin of safety set by the manufacturer usually does damage to the device by causing its operating temperature to exceed safe levels. In
496:
rating method for loudspeakers uses a shaped noise signal that simulates music and allows peak excursion of 6 dB, so an EIA rating of 50 Watts corresponds to 200 Watts peak rating.
211:
59:
may refer to electrical or mechanical power. A power rating can also involve average and maximum power, which may vary depending on the kind of equipment and its application.
312:
950:
251:
204:
282:
632: 1.5) and temperature of the cells at 25 °C. The power is measured while varying the resistive load on the module between open and closed circuit.
981:
538:
are rated for continuous power (which does not have a time constraint), takeoff and hover power rating (defined as half to one-hour operation), maximum
562:
1033:
1006:
934:
907:
846:
812:
782:
746:
719:
692:
1057:
324:
610:
493:
129:
862:
476:. As the power rating depends on the method of cooling, different ratings may be specified for air cooling, water cooling, etc.
1083:
957:
107:
640:
539:
103:
92:
879:
Danish proposal to a design CO2 index for new ships to the UN’s
International Maritime Organization (IMO) from the
111:
96:
635:
The maximum power measured is the nominal power of the module in Watts. Colloquially, this is also written as "W
656:
606:
1088:
838:
684:
44:
40:
553:
is reduced to less than half for continued operation at this level. The service factor is defined in the
254:
643:. The nominal power divided by the light power that falls on the module (area x 1000 W/m) is the
210:, the ambient temperature or temperature range in which the device will be operated, and the method of
55:
input allowed to flow through particular equipment. According to the particular discipline, the term
899:
31:
924:
542:
power (which can be sustained for two-three minutes), and emergency (half a minute) power rating.
287:
315:
217:
170:
1029:
1002:
996:
975:
930:
903:
893:
842:
832:
808:
802:
778:
742:
715:
709:
688:
678:
534:
In some fields of engineering, even a more complex set of power ratings is used. For example,
446:
163:
1023:
768:
736:
1054:
599:
260:
1061:
595:
558:
469:
438:
52:
866:
598:
power ratings are typically established by driving the device under test to the onset of
17:
468:, although for devices intended for use in large power systems, both may be given in a
465:
143:
628:
similar to sunlight hitting the Earth's surface at latitude 35° N in the summer (
1077:
569:
485:
420:
If all power in a device is dissipated as heat, then this is also the power rating.
550:
489:
639:"; this format is colloquial as it is outside the standard by adding suffixes to
590:
461:
442:
207:
155:
151:
81:
535:
457:
318:
between the device and ambient, then the maximum heat dissipation is given by
27:
Highest power input allowed to flow through electrical or mechanical equipment
774:
622:
515:
473:
154:, the power rating given is usually the maximum power that can be safely
147:
545:
For electrical motors, a similar kind of information is conveyed by the
629:
472:. Cables are usually rated by giving their maximum voltage and their
206:, must be calculated. This is related to the maximum safe operating
561:
standard, and is generally used in the United States. There is no
410:{\displaystyle P_{D,max}={\frac {T_{D,max}-T_{A}}{\theta _{DA}}}}
880:
554:
453:
159:
75:
711:
Plant
Engineers and Managers Guide to Energy Conservation
677:
Anthony G. Atkins; Tony Atkins; Marcel
Escudier (2013).
659:, the regulatory analog for VHF, UHF and FM broadcasting
445:, or transport it from one location to another, such as
926:
Mechanical
Engineering Reference Manual for the PE Exam
770:
Introduction to
Electrical Power and Power Electronics
158:
by the equipment. The usual reason for this limit is
327:
290:
263:
220:
173:
441:between different forms of electric power, such as
409:
306:
276:
245:
198:
741:. Morgan & Claypool Publishers. p. 74.
796:
794:
146:or converts it into mechanical power, such as
8:
995:Hamid A. Toliyat; Gerald B. Kliman (2004).
826:
824:
762:
760:
758:
110:. Unsourced material may be challenged and
1049:
1047:
1045:
30:For the rating system used in sports, see
1055:"How to Compare Amplifier Power Ratings."
396:
385:
360:
353:
332:
326:
295:
289:
268:
262:
225:
219:
178:
172:
130:Learn how and when to remove this message
804:The Electronics Handbook, Second Edition
714:. The Fairmont Press, Inc. p. 320.
669:
142:In equipment that primarily dissipates
980:: CS1 maint: archived copy as title (
973:
680:A Dictionary of Mechanical Engineering
892:John M. Seddon; Simon Newman (2011).
7:
108:adding citations to reliable sources
452:Power ratings are usually given in
929:. www.ppi2pass.com. pp. 72–.
25:
923:Michael R. Lindeburg, PE (2013).
831:Gary Davis; Ralph Johnes (1989).
611:Electronic Industries Association
565:standard for the service factor.
1067:. Retrieveded on March 18, 2010.
1028:. Cengage Learning. p. 81.
834:The Sound Reinforcement Handbook
284:is the ambient temperature, and
80:
807:. CRC Press. pp. 314–315.
801:Jerry C. Whitaker, ed. (2005).
518:, ships usually operate at the
484:For AC-operated devices (e.g.
1:
895:Basic Helicopter Aerodynamics
307:{\displaystyle \theta _{DA}}
51:of equipment is the highest
998:Handbook of Electric Motors
1105:
1025:Motor Control Fundamentals
1001:. CRC Press. p. 181.
735:William J. Eccles (2008).
620:
588:
437:In devices that primarily
433:Power converting equipment
29:
1053:Quilter, Patrick (2004).
881:Danish Maritime Authority
520:nominal continuous rating
505:Maximum continuous rating
500:Maximum continuous rating
246:{\displaystyle T_{D,max}}
199:{\displaystyle P_{D,max}}
18:Maximum Continuous Rating
767:Mukund R. Patel (2012).
657:Effective radiated power
607:Federal Trade Commission
839:Hal Leonard Corporation
708:Albert Thumann (2010).
685:Oxford University Press
411:
308:
278:
247:
200:
162:, although in certain
45:mechanical engineering
41:electrical engineering
1084:Electrical parameters
900:John Wiley & Sons
412:
309:
279:
277:{\displaystyle T_{A}}
255:operating temperature
248:
201:
72:Dissipative equipment
1022:Steve Senty (2012).
617:Photovoltaic modules
424:Mechanical equipment
325:
288:
261:
253:is the maximum safe
218:
171:
104:improve this section
32:Sports rating system
480:Average vs. maximum
1060:2010-01-11 at the
777:. pp. 54–55.
641:standardized units
605:For instance, the
536:helicopter engines
447:transmission lines
407:
316:thermal resistance
304:
274:
243:
196:
1035:978-1-133-70917-6
1008:978-0-8247-4105-1
936:978-1-59126-414-9
909:978-1-119-97272-3
848:978-1-61774-545-4
814:978-1-4200-3666-4
784:978-1-4665-5660-7
748:978-1-59829-798-0
721:978-0-88173-657-1
694:978-0-19-958743-8
530:Other definitions
405:
164:electromechanical
140:
139:
132:
16:(Redirected from
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1039:
1019:
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992:
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956:. Archived from
955:
947:
941:
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914:
913:
898:(3rd ed.).
889:
883:
877:
871:
870:
865:. Archived from
859:
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852:
837:(2nd ed.).
828:
819:
818:
798:
789:
788:
764:
753:
752:
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585:Audio amplifiers
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84:
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1062:Wayback Machine
1052:
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993:
989:
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966:
964:
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951:"Archived copy"
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937:
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910:
902:. p. 231.
891:
890:
886:
878:
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841:. p. 232.
830:
829:
822:
815:
800:
799:
792:
785:
766:
765:
756:
749:
738:Pragmatic Power
734:
733:
729:
722:
707:
706:
702:
695:
687:. p. 269.
676:
675:
671:
666:
653:
638:
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596:Audio amplifier
593:
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582:
532:
502:
482:
470:per-unit system
435:
426:
392:
381:
356:
355:
328:
323:
322:
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286:
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264:
259:
258:
257:of the device,
221:
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125:
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85:
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67:Equipment types
35:
28:
23:
22:
15:
12:
11:
5:
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1091:
1089:Electric power
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1065:Sound and Song
1041:
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987:
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872:
869:on 2013-09-03.
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621:Main article:
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589:Main article:
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583:
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578:
570:semiconductors
547:service factor
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466:apparent power
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144:electric power
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14:
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10:
9:
6:
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1004:
1000:
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991:
988:
983:
977:
963:on 2014-02-22
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529:
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486:coaxial cable
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314:is the total
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89:This section
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71:
66:
64:
60:
58:
54:
50:
46:
42:
37:
33:
19:
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1024:
1017:
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990:
965:. Retrieved
958:the original
945:
925:
918:
894:
887:
875:
867:the original
857:
833:
803:
769:
737:
730:
710:
703:
679:
672:
644:
634:
626:
604:
594:
574:
567:
551:service life
546:
544:
533:
523:
519:
513:
508:
504:
503:
490:loudspeakers
483:
462:volt-amperes
451:
443:transformers
436:
427:
419:
141:
126:
117:
102:Please help
90:
61:
56:
49:power rating
48:
38:
36:
591:Audio power
540:contingency
208:temperature
1078:Categories
967:2014-02-11
664:References
645:efficiency
458:real power
156:dissipated
120:March 2020
775:CRC Press
623:Watt peak
394:θ
379:−
293:θ
148:resistors
91:does not
1058:Archived
976:cite web
651:See also
600:clipping
580:Examples
516:shipping
474:ampacity
152:speakers
630:airmass
514:Within
439:convert
212:cooling
112:removed
97:sources
1032:
1005:
933:
906:
863:"IESO"
845:
811:
781:
745:
718:
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557:/NEMA
214:. If
150:, and
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961:(PDF)
954:(PDF)
454:watts
57:power
53:power
1030:ISBN
1003:ISBN
982:link
931:ISBN
904:ISBN
843:ISBN
809:ISBN
779:ISBN
743:ISBN
716:ISBN
689:ISBN
559:MG 1
555:ANSI
464:for
460:and
456:for
160:heat
95:any
93:cite
43:and
563:IEC
524:NCR
509:MCR
494:EIA
106:by
39:In
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Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
