5E-i APPENDIX 5E. E LECTRO M AGNETIC I NTERFERENCE

TABLE OF CO NTENTS

5E.1 OVERVIEW

........................................................................................................................ 1 5E.2 DESCRIPTION

................................ ................................ .................................................... 1 5E.3 EMI

- SENSITIVE APPLICATIO NS

................................................................................... 1 5E.4 REGULATIONS

................................ ................................ .................................................. 2 5E.5 REDUCTION AND MITIGA TION

.................................................................................... 3 5E.6 CONCLUSION

.................................................................................................................... 4

LIST OF TABLES

Table 5E.1 Conducted EMI Requirements for Fluo rescent Lamp Ballasts .....................................35E

- 1 APPENDIX 5E. E LECTRO M AGNETIC I NTERFERENCE

5E.1 OVERVIEW

In this appendix, DOE presents research regarding electromagnetic interference, or EMI, generated by electronic ballasts and possible methods to reduce th ese emissions

. DOE also identifies specific applications that may be sensitive to the electromagnetic interference emitted by electronic ballasts

.

5E.2 DESCRIPTION

EMI can be defined as unwanted effects in an electrical system due to electromagnetic radiation and electromagnetic conduction from an external source . Electromagnetic radiation and electromagnetic conduction are differentiated by the way an electromagnetic field propagates. Conducted EMI is often the result of physical contact of the conductors , whereas radiated EMI is the result of electromagnetic induction from the external source to the affected electrical system. An EMI problem consists of a source, a coupling path, and an affected device.

The source of EMI in a fluorescent lamp

- and

- ballast system consists mainly of switchingcomponents (transistors) in the ballast and the fluorescent lamp and lead wires. In highfrequency electronic ballasts, switching components create rapidly changing electric fields which

can result in the generation of harmonic wa ves

. These harmonic waves cause noise and voltage spikes, which can interfere with the function of other circuits on the line. Commercial electronic ballasts use switching components in the resonant inverter and power factor correction stages, while residential ballasts possess fewer switching components because they typically do not have a power factor correction stage. Low -frequency magnetic ballasts do not have switching components, dramatically reducing EMI generation. The second major source of EMI is the fluorescent lamp and ballast leads. The lamp and lead wires create a loop which in the presence of a rapidly switching AC waveform creates an antenna for radiated EMI. This phenomenon is more pronounced with electronic ballasts compared to magnetic bal lasts.

Once the electric field is created, it must travel to the affected device to create interference. This can occur via conduction through the ballast into the building wiring or common ground connections to another device. EMI can also radiate via ant ennas or parasitic capacitances and inductances between conductors. EMI does not have to follow a strictly conducted or radiated path. For example, the radiated EMI generated by the lamp and lead wires can induce unwanted currents in the ballast itself which can then propagate through the building wiring to external devices. Finally, when EMI come s into contact with conductive material in the external device

, it can induce currents that lead to device malfunction.

5E.3 EMI

- SENSITIVE APPLICATIO NS

DOE conducted re search and interviews with fluorescent lamp ballast and fixture manufacturers to identify several applications as potentially sensitive to electromagnetic interference . These applications include, but are not limited to : medical operating room telemetry

or life support systems; airport control systems; electronic test equipment; radio communication5E

- 2 devices; radio recording studios; correctional facilities; clean rooms; research laboratories; facilities with low signal to noise ratios; and aircraft hangers o r other buildings with predominantly metal construction. These applications require ballasts that generate no or low levels of EMI.

5E.4 REGULATIONS

To understand the specifications that ballast consumers require for different applications, DOE researched exist ing regulations for EMI. DOE identified current standards for general applications such as commercial buildings, residential buildings, naval vessels, and other spaces.

T he Federal Communications Commission (FCC) (47 CFR part 18) has standards which “regu late industrial, scientific, and medical equipment (ISM) that emits electromagnetic energy on frequencies within the radio frequency spectrum in order to prevent harmful interference to authorized radio communication services”. There are separate standards for consumer (residential) and non-consumer equipment and also for both radiated and conducted emis sions. However, d evices that operate at frequencies less than 1.705 megahertz ( MHz ), such as fluorescent lamp ballasts, are not required to report measureme nts of radiated emissions that exist at frequencies greater than 30 MHz. Because FCC regulations for the field strength of radiated emissions only exist for frequencies above 30 MHz, these standards do not apply to fluorescent lamp ballasts

DOE also iden tified requirements for electromagnetic interference in Department of Defense MIL

- STD -461F a . The standards in section CE102 apply to conducted emissions from power leads between 10 kHz and 10 MHz while the standards in section RE102 apply to radiated emiss ions between 10kHz and 18GHz. These standards establish “interface and associated verification requirements for the control of the EMI emission and susceptibility characteristics of electronic, electrical, and electromechanical equipment and subsystems des igned or procured for use by activities and agencies of the Department of Defense (DoD).” Table 5E .1 shows the existing FCC and military standards for conducted electromagnetic interference. The frequency column indicates the frequency of the electromagnetic interference rather than the frequency at which the ballast operates.

The conducted EMI limits in MIL

- STD -461F are given in units of decibel-microvolt (dB μV ). Decibel

- microvolt is converted to μV using the following formula:

Where A 0 is the reference limit of 1 μV , L dB is the limit in dB μV , and A 1 is the corresponding limit in μV . DOE converted the MIL- STD -461F limits for comparison to the FCC standards.

a Department of Defense MIL

- STD

- 461F is available at http://www.cvel.clemson.edu/pdf/MIL

- STD

- 461F.pdf . Last accessed April 4 , 2011.5E

- 3 Table 5E.1 Conducted EMI Requirements for Fluorescent Lamp Ballasts

Frequency (MHz) FCC Title 47 Part 18 conducted EMI, Maximum RF line voltage measured with a 50 uH/50 ohm LISN ( μV ) Limit Level using CE 102 Test Procedure from Military Standard 461F, conducted emissions for all applications ( μ V ) Non

- consumer equipment: 0.45 to 1.6 1,000 1,000 1.6 to 30 3,000 1,000* Consumer equipment: 0.45 to 2.51 250 1,000 2.51 to 3.0 3,000 1,000 3.0 to 30 250 1,000* *Applies up to 10 MHz

T he first rev i ew of energy conservation standards for fl uoresc ent lamp ballasts was
comp leted in September 2000 (2000 Ballast Rule, 65 FR 56740). In that rulemaking , DOE considered “t he possibility of interference with certain equipment, such as medical monitoring equipment, caused by the high frequency of electronic ballasts .” The 2000 Ballast Rule therefore did not regulate T8 ballasts because of concerns that manufacturers would not be able to produce an electronic ballast that did not interfere with other equipment. It specifically stated that by not regulating T8 ballasts, magnetic T8 products could continue to be used in EMI- sensitive applications. 65 FR 56740, 56743 (September 19, 2000).

5E.5 REDUCTION AND MITIGA TION

EMI from magnetic ballasts ( which operate at line frequency ) has considerably lower intensity than EMI from electronic ballasts because EMI intensity is directly proportional to operating frequency. Furthermore, magnetic ballasts do not use switching components to increase the operating frequency of the lamp. Switching is a major contributor to EMI in electronic ballasts. Magnetic ballasts are frequently specified for EMI -sensitive applications, but are not likely to be able to meet efficiency levels proposed in this NOPR. DOE identified several

means of reducing or mitigating EMI that could potentially b e used in electronic fluorescent ballasts.

External EMI filters can be installed on the line side of an electronic ballast to limit unwanted conducted EMI from entering the building wiring . Additionally , a fixture can be designed with a grid lens or ground ing cage to cover the lamp chamber in order to increase the impedance to a specific frequency and to bring radiated EMI to ground. Although ballasts do not have to meet FCC standards for radiated EMI, this type of EMI still presents a practical issue and fixture manufacturers must account for it. Because high frequency EMI has a very short wavelength, it can escape fixtures through very small openings, making high quality fixture design important.

Measures can also be taken to limit the vulnerability of the sensitive external device to EMI. Shielding made of conductive material can mitigate the effects of EMI on susceptible equipment. The intensity of EMI decreases as it radiates outward from the source, so the risk to susceptible equipment decreases if it i s placed farther from the EMI source. However, distance is5E

- 4 not always sufficient, and it is not always possible to design a layout that maintains a safe distance between fluorescent ballasts and EMI -sensitive equipment.

5E.6 CONCLUSION

DOE learned from manufacturer interviews that magnetic ballasts are typically recommended for situations in which EMI has been or is expected to be a concern. Manufacturers indicated uncertainty over the effectiveness of these measures for each individual application. DOE was also unable to determine whether EMI related issues with electronic ballasts could be eliminated with the methods described above. Manufacturers suggested that an exemption for T8 magnetic ballasts would not constitute a risk for magnetic ballast substitution in current electronic ballast applications because magnetic ballasts are generally heavier, more expensive, and use more energy than electronic ballast alternatives. Customers generally prefer magnetic ballasts only in situations where EMI is a particular concern.

Based on its analysis of EMI -sensitive ballast applications, DOE proposes that T8 magnetic ballasts designed and labeled for use in EMI -sensitive environments only and shipped by the manufacturer in packages containing not more than 10 ballasts be exempt from the standards established in the NOPR. Because of the diversity in magnetic T8 ballast applications, DOE has designed the exemption similar to the previous fluorescent lamp ballast exemptions for replacement ballasts. DOE believes the exempt ion is necessary because in some environments, EMI can pose a serious safety concern that is best mitigated with magnetic ballast technology. DOE does not believe magnetic ballasts would likely be used as substitutes in current electronic ballast applicati ons due to their higher cost and weight.