1、NEMA Standards PublicationNational Electrical Manufacturers AssociationNEMA LSD 8-2014Power QualityImplications ofSelf-ballasted Lamps inResidences 2014 National Electrical Manufacturers Association A NEMA Lighting Systems Division Document LSD 8-2014 Power Quality Implications of Self-ballasted Lam
2、ps in Residences Prepared by: NEMA Lamp and Ballast sections National Electrical Manufacturers Association 1300 North 17th Street, Suite 900 Rosslyn, Virginia 22209 Approved: December 11, 2014 Published: June 26, 2015 www.nema.org The requirements or guidelines presented in this document, a NEMA Lig
3、hting Systems Division white paper, are considered technically sound at the time they are approved for publication. They are not a substitute for a product sellers or users own judgment with respect to the particular product discussed, and NEMA does not undertake to guarantee the performance of any
4、individual manufacturers products by virtue of this document or guide. Thus, NEMA expressly disclaims any responsibility for damages arising from the use, application, or reliance by others on the information contained in these white papers, standards, or guidelines. The opinions expressed in this s
5、tatement represent the consensus views of the member companies of the Lighting Systems Division of the National Electrical Manufacturers Association. The members of the Lighting Systems Division manufacture traditional technology lamps and ballasts, light-emitting diodes (LEDs and OLEDs), LED lamps
6、and modules, LED drivers and power supplies, luminaires, lighting controls, and management systems. NEMA LSD 8-2014 2014 National Electrical Manufacturers Association 2 Contents Overview . 3 1 Scope 4 2 Benefits of Self-ballasted Lamps 4 3 Power Quality Aspects of Self-ballasted Lamps 4 3.1 Backgrou
7、nd . 4 3.2 A Perspective 5 3.3 Residential Self-ballasted Lamp Application and Use 5 3.4 Power Factor . 5 3.5 Harmonic Currents and THD . 6 3.6 Supporting Data 7 3.7 Models vs Data Monitoring in the Field . 11 4 Conclusions . 12 5 Postscript: Self-ballasted Lamps in Light Commercial Applications 12
8、Figures Figure 1 CFL Power Factor Implications . 6 Figure 2 Mixed/Aggregate Loads at Branch Circuit 8 Figure 3 Mixed/Aggregate Loads at Branch Circuit 8 Figure 4 Current Waveform, Single LPF Self-ballasted Lamp Load . 9 Figure 5 Current Waveform, Aggregate LPF Self-ballasted Lamp Load 9 Figure 6 Com
9、bined Current Waveform . 10 Figure 7 Sum of Harmonic Currents vs Harmonic Order for CFLs . 10 Tables Table 1 THD from Mixed Loads . 7 Table 2 Typical Lighting Load Characteristics: Aggregate Field Effect Implications and Typical System Mitigation 11 NEMA LSD 8-2014 2014 National Electrical Manufactu
10、rers Association 3 OVERVIEW The presence of high-reliability, low-cost electronic products continues to grow in the market. From a power systems perspective, these products can represent non-linear loads. They include entertainment devices, such as televisions, DVD players, and audio equipment; info
11、rmation technology devices, such as PCs, printers, and fax machines; variable speed motor drives for heating, ventilation, and air conditioning (HVAC); white goods appliances; food preparation and cooking products, such as microwaves and cooktops; and lighting products, which include electronic ball
12、asts, self-ballasted compact fluorescent lamps (CFLs), light-emitting diode (LED) lamps, and other power conversion devices that operate a variety of lamps. This proliferation is a direct result of the availability of low-cost switch mode devices and control circuitry, and the benefits such technolo
13、gy can bring to end users, including: a) lower operating costs b) energy cost savings c) short economic paybacks, often under two years d) more features, improved performance e) size and weight reduction f) improved form factors g) reduction of fossil fuel generation of electricity, causing less pol
14、lution From a utilites perspective, the proliferation of such products results in an increased growth of non-linear loads. Products with non-linear loads are not new, but we have entered a period where growth continues in all major end-use segments: residential, commercial, and industrial. This grow
15、th has led to an increased concern by some utilities about the effects on power quality from such loads. Some utilities are more concerned than others, but it is fair to say that utilities which are focused on such issues are expending more effort to instrument their service areas so they can monito
16、r THD(V) in an attempt to correlate end user and system disturbances with the increase of such loads within their service areas. At the highest levels, utilities are concerned with distortion to the voltage waveform they supply to their customers, but they are also concerned with the effects of non-
17、linear loads on their distribution infrastructure, which can include capital equipment and added heating losses within the systems. Some are concerned with disturbances that might occur in customers premises, since thosecustomers might attempt to fix blame for local interaction problems on the power
18、 quality as supplied by the utility. This white paper does not go into detail on the fundamentals of the above issues. There are many papers that address this subject from a utility perspective. This white paper seeks to put into perspective the subject of self-ballasted lamps and explain why the ef
19、fects presented by these lamps, from a power quality perspective, are not as severe as has sometimes been postulated. NEMA LSD 8-2014 2014 National Electrical Manufacturers Association 4 1 Scope This white paper provides information about self-ballasted lamps and the implications these lamps present
20、 from a power quality perspective. It focuses on the use of self-ballasted lamps in residences and on residential power quality. Self-ballasted lamps have dedicated ballasts that are part of the lamp itself, which allows the lamp to be used in some sockets that originally were meant for incandescent
21、 lamps. The ballast intercepts the electrical current before it enters the bulb itself, and it cannot be removed from the base. Some CFLs and some LED lamps are examples of self-ballasted lamps. Utilities are often internally conflicted on the issue of residential power quality. Engineering departme
22、nts tend to be conservative, since they are entrusted with the reliability of the system. Accordingly, they also tend to be risk averse regarding power quality issues, even when the loads are small and experience indicates that problems have yet to occur with products, such as nonpower factor (PF) c
23、orrected self-ballasted lamps (also called normal power factor, but the terms low power factor and nonpower factor corrected will be used interchangeably in this document). This white paper presents information from work started in the late 1990s using CFLs in aggregate and with other loads to try t
24、o better understand why non-power factor corrected CFL usage posed no problems during introduction of self-ballasted lamps into the residential marketplace. It is hoped that this paper also will help to justify why utilities should not hesitate to support and endorse the use of self-ballasted lamps,
25、 even nonpower factor corrected versions. 2 Benefits of Self-ballasted Lamps A brief review of self-ballasted lamp benefits is helpful to set the stage. Self-ballasted lamps use approximately 15-25% of the power that would be consumed by traditional incandescent lamps with an equivalent light output
26、. End users and energy advocacy groups realize the savings this can represent in energy costs and the preservation of natural resources. Such performance provides benefits for utilities that are often looking for ways to reduce connected load or for strategies that can help slow the increase in over
27、all demand. Thus, the sometimes-conflicted utility dilemma. One department might want to promote low-cost, nonPF corrected self-ballasted lamps, while another cautions against the possible detrimental effects to system power quality. Since the technology used is fluorescent or LED, which has a much
28、longer life than incandescent technology, self-ballasted lamps easily achieve rated lifetimes that are 13 times longer in use. This feature alone often convinces the end user to try self-ballasted lamps in high-usage applications, despite their higher initial cost. Since nonPF corrected self-ballast
29、ed lamps draw approximately 25% or less current than their incandescent counterparts, self-ballasted loads reduce current losses that occur throughout the distribution infrastructure, both on the utility side and within the users premesis. 3 Power Quality Aspects of Self-ballasted Lamps 3.1 Backgrou
30、nd This section provides a review of the power quality aspects of nonPF corrected self-ballasted lamps. (This white paper concentrates on this category, since it is these self-ballasted lamps that are lowest in cost and represent the best opportunity for consumer acceptance.) Energy efficiency and e
31、nergy savings related to power usage leads to a reduction of up to 25% savings compared with the equivalent incandescent lamp. That leads to reduced I2R distribution losses through the electrical infrastructure. Power factor is lower than for an incandescent lamp: typically 0.5 for low- or nonpower
32、factor corrected types. Some power factor corrected models have a power factor that ranges from 0.8 through greater than 0.9. Total harmonic distortion (THD) and harmonic currents are greater than an incandescent lamp; THD(f) for current is typically 150%. Harmonic currents are on the order of 15 mA
33、 per watt. Low-distortion self-ballasted lamps have THDs less than 32%, but costs for such systems drive up the price, increase size, and reduce product performance to some degree. NEMA LSD 8-2014 2014 National Electrical Manufacturers Association 5 3.2 A Perspective Given the above, it is difficult
34、 to understand why utilities think there is a power factor problem with self-ballasted lamps. Todays self-ballasted lamps are more reliable, lower cost, smaller, more attractive, and offer higher performance than ever before. Overall, they have an excellent history in residential and commercial inst
35、allations. Manufacturers are aware of no power quality problems from such products, either within installations or at the distribution level. These self-ballasted lamps, however, are often included in todays general debate on power quality and sometimes are not endorsed by utilties for incentive pro
36、grams. This concern is not justified, since there are simply no documented problems attributed to the distributed load from self-ballasted lamps, even in areas of the country where energy rates are high and there is reasonable product demand. 3.3 Residential Self-ballasted Lamp Application and Use P
37、ower system engineers are generally familiar with loads that replace equivalent loads even when technology is upgraded. A more efficient horsepower motor drive still drives a horsepower motor. Self-ballasted lamp usage is different. Manufacturers did not design these lamps to use the same energy as
38、the incandescent lamps they replace. Most self-ballasted lamps are designed and used to replace an incandescent lamp at approximately the same light level, since it is the light level a consumer seeks. Unlike most other non-linear loads, end users (local environment) and utilities (point of common c
39、oupling PCC and back into the distribution system): a) see much lower power consumption per lamp replaced (25% of incandescent wattage); b) see much lower RMS current draw per lamp replaced, even for low or nonPF corrected products; c) benefit from reduced I2R losses; d) see only a small increase in
40、 harmonic currents (mA/watt). 3.4 Power Factor Sections 3.4 and 3.5 explain the two most common elements of power quality: PF and harmonic currents (THD) for self-ballasted lamps. It can be shown that even a low-PF self-ballasted lamp draws much less total RMS current than does the incandescent lamp
41、 it replaced. This means that if we consider only PF, a low-PF self-ballasted lamp actually has better power quality, from an RMS current demand perspective, than the original incandescent lamp with its 1.0 PF! This is shown dramatically in Figure 1. Note that the CFL PF could degrade all the way to
42、 0.3 and still draw less RMS current than the original 100 W incandescent lamp it replaced. NEMA LSD 8-2014 2014 National Electrical Manufacturers Association 6 Figure 1 CFL Power Factor Implications PF would be an issue only if self-ballasted lamp manufacturers produced lamps with the same equivale
43、nt wattage level as the incandescent lamps they replaced. This, however, would provide no user benefit and would not be accepted. Low PF is not an issue for residential self-ballasted lamps. 3.5 Harmonic Currents and THD Residential self-ballasted lamps pose no threat to the utility system or the lo
44、cal premises environment. At the time this white paper was published, NEMA data showed market share for self-ballasted lamps to be approximately 35%. More information is available at www.nema.org. The rated wattage of CFLs on the market today is typically 13-23W. The average power level of LED self-
45、ballasted devices is approximately 8-15W, with a corresponding reduction in harmonic current. LED lamps that produce light output similar to CFLs consume less power at a higher power factor. Therefore, the correponding harmonic currents are significantly lower than CFLs. The worst-case third harmoni
46、c current associated with such a self-ballasted lamp is approximately 200 milliamps. There is no conclusive evidence that such harmonic currents circulating within a local residential branch circuit are problematic. Other consumer products have circulated similar currents for decades. There is no co
47、nclusive evidence that even aggregate self-ballasted lamps produce aggregate harmonic currents that have caused problems with local low-voltage utility transformers serving multiple residences, or that such harmonic currents result in unacceptable voltage distortion on either the primary or secondar
48、y side of the residential service transformer, or that such self-ballasted lamp harmonic currents from residences cause unacceptable THD(V) levels at locations upstream from the residence. NEMA LSD 8-2014 2014 National Electrical Manufacturers Association 7 3.6 Supporting Data Data taken on a typica
49、l commercial branch circuit and at the load center in a typical residence show that the addition of other types of loads commonly found in residences dramatically swamps out or dilutes any possible component of harmonic current provided by the lower-power self-ballasted lamps. See figures 2, 3, and 4 for typical results. While specific results will vary with local line impedances and internal residential circuit impedances, overall effects are indicative of what typically happensand help to explain why such products have not caused problems. (Note, too, that
