1、NEMA Standards PublicationNational Electrical Manufacturers AssociationNEMA LSD 74-2016Considerations of Field LED Driver Replacement 2016 National Electrical Manufacturers Association A NEMA Lighting Systems Division Document LSD 74-2016 Considerations of Field LED Driver Replacement Prepared by: N
2、EMA Ballast and Driver Section National Electrical Manufacturers Association 1300 North 17thStreet, Suite 900 Rosslyn, Virginia 22209 Approved: March 17, 2016 Published: www.nema.org The requirements or guidelines presented in this document, a NEMA Lighting Systems Division white paper, are consider
3、ed technically sound at the time they are approved for publication. They are not a substitute for a product sellers or users judgment with respect to the particular product discussed, and NEMA does not undertake to guarantee the performance of any individual manufacturers products by this document o
4、r 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 statement represent the consensus views of the member companies
5、 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 and modules, LED drivers and power supplies, luminaires, light
6、ing controls and management systems. NEMA LSD 74-2016 Page 2 2016 National Electrical Manufacturers Association CONTENTS 1 Scope 4 2 References . 4 3 Definitions and Output Characteristics 4 3.1 Constant Voltage or Constant Current 4 3.2 Class 1 or Class 2 . 4 3.3 Programmability or “Tuning” 4 4 Con
7、trol Characteristics 5 5 Input Characteristics 5 6 Electromagnetic Interference Characteristics . 5 7 Programmability or Tunability Aspects 5 8 Tuning Techniques . 6 8.1 Importance of Tuning 6 8.2 Additional Related Tuning Issues 6 9 Field Replacement of Drivers. 6 9.1 Using same manufacturer replac
8、ement driver 6 9.2 Using a different manufacturer replacement driver . 6 10 Summary 7 11 Conclusion . 7 NEMA LSD 74-2016 Page 3 2016 National Electrical Manufacturers Association Introduction Because LED lighting continues to grow in the market, the need to replace failed drivers presents a unique s
9、et of requirements. Unlike fluorescent ballasts, drivers are not similarly interchangeable. Drivers vary in output characteristics and electrical safety ratings. With respect to output characteristics, a driver can be constant voltage, constant current, or other types of output. The output can also
10、vary in terms of safety rating, such as Class 1 or Class 2 outputs. The driver in question could also be programmable or tuned, and set to some output characteristic less than the maximum rating of the driver. The tuning or programming could have been done by the original equipment manufacturer (OEM
11、), driver manufacturer; the fixture manufacturer on a lot or batch basis; or by the installer in the field, especially in retrofit applications. The driver can be a dimming driver with Digital Addressable Lighting Interface (DALI), phase, 0-10VDC, wireless or other types of control. This paper makes
12、 the reader aware of driver characteristics and describes the steps necessary to ensure the correct replacement driver is obtained. This paper is written for individuals who are tasked with the field repair of LED fixtures, including contractors and building maintenance personnel. NEMA LSD 74-2016 P
13、age 4 2016 National Electrical Manufacturers Association 1 Scope The scope of this paper is a discussion of issues related to the field replacement of drivers in LED lighting fixtures. This paper explains that several aspects must be considered to ensure the replacement driver will function in the s
14、ame way as the original driver. The paper also discusses applicable safety standards related to driver replacement. 2 References NEMA LSD 73-2015 Energy Savings with Fluorescent and LED Dimming ANSI C82.15 LED Driver Robustness NFPA 70 National Electrical Code3 Definitions and Output Characteristics
15、 3.1 Constant Voltage or Constant Current The driver is designed to output a constant voltage level (such as 24V) at any current from the minimum rating up to the maximum rating of the driver, and is designed to output a constant output current (such as 700 mA) over a range of compliance voltages. T
16、he compliance voltage is typically a range, such as 16-54V, depending on the application. 3.2 Class 1 or Class 2 Drivers are rated by safety agencies as suitable for Output Power Circuit, Class 1 or Class 2. These ratings are found in the National Electrical Code, and describe the proper operating a
17、nd safety characteristics. To maintain system integrity, if a Class 1 driver exists in the field, it must be replaced with a Class 1 driver. Similarly, if a Class 2 driver exists in the field it must be replaced with a Class 2 driver. Class 1 drivers have output voltages similar to fluorescent balla
18、sts, as they are also Class 1 devices, so there is some risk of shock or arcing. Class 1 drivers have higher output voltages and output power limits than Class 2 drivers. Class 2 drivers are considered inherently safe, and are required in some fixtures that use polymeric materials that are suitable
19、for Class 2 systems only. Certain fixtures such as decorative types may have exposed wiring that must have the voltage limited to minimize risk of shock. 3.3 Programmability or “Tuning” To utilize economy of scale in the manufacture of drivers, drivers may be designed with a maximum rating based on
20、electrical components used, and then specifically programmed or tuned to set the maximum output characteristic (typically current) that is required by a specific LED load. This tuning or programming capability allows the fixture manufacturer to define light levels on the production line to meet the
21、needs of specific applications. Tuning capability is used to match the OEM light level. Tuning can be implemented digitally although the use of a programmer module connected to the driver or by an external programming resistor that is used to set an upper or lower current limit. The OEM may do the t
22、uning in the factory or by the installer in the field, dependent on the manufacturer. NEMA LSD 74-2016 Page 5 2016 National Electrical Manufacturers Association 4 Control Characteristics Dimming In order for the end user to manage the lighting levels, dimming drivers are used. There are three main c
23、ontrol schemes for dimming drivers. These include the DALI digital system, a phase control that uses a wall box or similar line voltage phase-control dimmer (See SSL 7A), and 0-10VDC low-voltage control. These control schemes are implemented in a manner similar to fluorescent ballasts and are mentio
24、ned here to ensure they are taken into consideration during a driver replacement. Phase-dimming systems, if not explicitly marked, can look similar to a fixed-output system, as there are no separate control leads. 0-10VDC and DALI systems will always have a set of low voltage control leads. Refer to
25、 NEMA LSD 73-2015 Energy Savings with Fluorescent and LED Dimming for additional information regarding dimming control schemes. 5 Input Characteristics Most drivers today are universal 120-277V, 50-60Hz. However, this is not always the situation. Some drivers are fixed or single voltage, and the rep
26、lacement driver must function properly on the supplied mains voltage. 6 Electromagnetic Interference (EMI) Characteristics The final aspect to consider is the EMI generated by the driver. If the driver is used in a residential application, the driver is typically rated Class B for consumer applicati
27、ons. Class B drivers have lower levels of EMI than drivers rated Class A that are intended for commercial and industrial applications. A Class A, non-consumer rated driver in a residential application could cause interference in AM radios and television reception. 7 Programmability or Tunability Asp
28、ects The ability to tune a driver is the ability for an OEM manufacturer to set the output current range in a constant current driver. Why tune a driver? Tuning allows the user to: a) design the proper lumen package for a space, b) correctly match the driver to the light source or LED module, and c)
29、 ensure compliance with applicable energy use regulations. LED modules are distinctly different and vary greatly (not standard, like fluorescent lamps) with reference to physical layout of chips, lumen output, and efficacy. All of these items are factors in determining the appropriate drive current
30、for the LED module. Once the drive current of the design is determined, it is “tuned” or “set” at the factory by the driver manufacturer or the fixture OEM. NEMA LSD 74-2016 Page 6 2016 National Electrical Manufacturers Association 8 Tuning Techniques Digital programming is the most prevalent tuning
31、 technique used by major manufacturers. Manufacturers may have a different tuning technique, in which case the user may not be able to apply one manufacturers technique to another. Another method uses a resistor (sometimes contained in the light module) to set the current limit. 8.1 Importance of Tu
32、ning Of all the characteristics mentioned above, some are readily determined, but the programming or tuning is the most difficult to determine and replicate. It is very important to get this aspect correct. Issues may result from setting the current too high or too low. If the current is too low, th
33、e driver is often returned to the place of purchase because the fixture appears dimmer than the surrounding fixtures. If the current is set too high, the fixture may be brighter than the surrounding fixtures. Too high of a current may also lead to short life of the light module, and will also void t
34、he original configuration that was approved by the safety agency. In addition, some jobs are approved because of energy savings incentives. The proposed savings may not be achieved with the higher level energy levels. 8.2 Additional Related Tuning Issues 8.2.1 An industry standard for driver tuning
35、does not exist. 8.2.2 Driver-tuning processes are primarily designed for use on the OEM line, not in the field. If tuning is done in the field, specialized tools and processes are needed, due to general incompatibility of the tuning methods and processes that vary with the OEMs. 8.2.3 Field tunabili
36、ty is not desiredthe ability for a customer to increase the lumen output and change efficiency after-the-fact would void any ability for rebates, ASHRAE, and Title 24 code requirements. 8.2.4 Readily providing information and programmer devices may allow the end user to inappropriately tune a replac
37、ement driver for greater light. Information and programmer devices should only be available from the OEM to qualified contractors or maintenance personnel. 9 Field Replacement of Drivers 9.1 Using the Same Manufacturer Replacement Driver Determine the model number and tune levelmost manufacturers pr
38、int the tune level on the driver label. With these two pieces of information a user can order a properly tuned driver for field replacement from the OEM fixture manufacturer or the OEM driver manufacturer. 9.2 Using a Different Manufacturer Replacement Driver a) Determine the rated current for the m
39、odule array by consulting the OEM fixture or light module manufacturer. These OEMs may also have a list of suitable replacements and characteristics. b) It is important to note that the tune values typically do not transfer between manufacturers. NEMA LSD 74-2016 Page 7 2016 National Electrical Manu
40、facturers Association c) In some cases, the user may need to examine the light engine for the type of LEDs used if this information is not included in the nomenclature. Round versus square LED package could mean different LED manufacturers as well as different drive currents. A photograph would be u
41、seful to document the exact LED shape. d) The programming parameters may “live” in the driver, but they are determined by the requirements of the light engine, so the fixture label or installation instructions should contain something about driver replacement and characteristics of the system. In al
42、l cases, taking a photograph of the label and the light engine is recommended. This will contain information that is useful to the OEM. The additional information may not be readily apparent, but a photograph should capture all the information necessary to ensure a correct replacement. 10 Summary In
43、 summary, ensure the following items are considered in replacement of a driver: a) Class 1 vs. Class 2 UL rating b) Input voltage c) Current tune level d) Temperature rating e) Dimming interface 11 Conclusion In conclusion, there are many factors that affect the system operation. Particular care must be taken to get the correct replacement driver for the application.
