1、UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM ULUNDERWRITERS LABORATORIES INC. CERTIFICATION REQUIREMENT DECISIONThis Certification Requirement Decision is prepared and published by Underwriters Laboratories Inc.(UL). It is normative for the a
2、pplicable UL Product Certification Program(s); however, it is currently notpart of the UL Standard(s) referenced below.Product Category (CCN): QIIO, QIKHStandard Number: UL 1741Standard Title: Standard for Inverters, Converters, Controllers and InterconnectionSystem Equipment for Use With Distribute
3、d Energy ResourcesEdition Date: April 20, 2010Edition Number: 2Section / Paragraph Reference: Sec. 101 to 107Subject: Clarification for PV Input Circuit Combiners and PV Combiner BoxesThis Certification Requirement Decision (CRD) supercedes prior CRD issued June10, 2011.DECISION:The requirements bel
4、ow, (include new definitions and Sections 101 107) are to be used for theevaluation of PV combiner boxes and other PV equipment that include a means to combine multiple PVinput source circuits.This document includes revisions to the original CRD issued on April 20, 2010.DefinitionsPV Circuit Combine
5、r - A product that connects the outputs of multiple photovoltaic source circuits into acombined output circuit or circuits. These devices are commonly referred to as a PV combiner box or PVstring combiners. These products will be referred to as “combiner unit(s)” to minimize text.Add the following S
6、ections to UL1741.101. PV Circuit Combiners and PV Combiner BoxesGeneral A combiners rated input current is the continuous operating current for which each individualcombiner input circuit is rated and that value correlates to the definition of maximum current as defined inarticle 690.8(A)(2) of the
7、 NEC. A combiners rated output current is the continuous operating current thatcan be carried by a combiners output circuit, and that value correlates to the definition of maximumcurrent as defined in article 690.8(A)(2) of the NEC.101.1 The requirements in Sections 101 107 supplement and, in some c
8、ases, amend the requirementsin Sections467.101.2 Products that combine multiple PV input circuits shall comply with the requirements in section 101 107.101.3 Overcurrent protection within a PV circuit combiner unit shall have a voltage rating not less than therating of the combiner unit.101.4 A PV c
9、ombiner shall be rated for and be suitable to accommodate at least the minimum wire sizeand Overcurrent Protective Device, (OCPD) ratings as defined by NFPA 70 Sections. 310.15, 690.8 A) 1)and 690.8 B) 1).UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSI
10、ON FROM UL101.5 Combiner units rated for use in non-isolated or ungrounded arrays shall include OCPDs in both thepositive and negative input conductors and shall be identified for the purpose per 104.3.101.6 Combiner units that include electronic PV system protection functionality including but not
11、limitedto; ground fault monitoring, PV array isolation measurements, Arc fault monitoring, voltage control forvirtual grounding systems, interruption, isolation or disconnection functionality shall be evaluated per theother applicable portions of UL 1741 and UL 1741 CRDs.102 Temperature Test102.1 Th
12、e Temperature test shall be run as follows.a) The Temperature Test described in Section 43 is to be performed with input and outputcircuits loaded as described in sections 102.2 through 102.5.b) The test current in each of the multiple input circuits shall be adjusted and monitoredindependently to p
13、roduce the maximum heating of the combiner unit.c) The combiner unit shall be mounted as specified in the manufacturers instruction. If multipleorientations are allowed the unit shall be tested in the orientation that is most likely to increaseoperation temperature.d) For purposes of the temperature
14、 test only, tests shall be performed under one of thefollowing conditions;1) With OCPDs rated for 125% of the input rating (or the next larger standard size if125% of the input rating falls between standard size increments),2) With OCPDs designed for use at 100% rated equal to the input rating, or3)
15、 With a dummy fuse used in place of fuse based OCPD in accordance with thefollowing considerations :i) Dummy fuses shall be un-plated copper strips or rods and shall conform tothe dimensions of the fuse type intended to be installed in the product asdescribed in the appropriate Standard covering the
16、 equipment.ii) Polymeric materials in close proximity, contact with, or used for directsupport of the electrical contacts of the fuseholder shall not exceed their RTIrating minus 20C (36F).iii) Wire insulation to the fuseholder shall not exceed the temperature ratingminus 20C (36F)102.2 The total ou
17、tput current during the test shall be at least equal to 100% of the combiner rated outputcurrent.102.3 During the test the individual combiner input currents at each input circuit shall be adjusted to within2% of the Rated input current. When the individual combiner inputs are mounted vertically, th
18、euppermost input circuit(s) located physically at the top of the combiner unit, shall be adjustedindependently to not less than 100% of its input rating, and operating temperatures shall be measured onSTANDARD NUMBER: UL 1741 -2-UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTR
19、IBUTION WITHOUT PERMISSION FROM ULthe connected components in that circuit. For other orientations (e.g. horizontally mounted, etc.), theinput circuits shall be loaded as noted above and temperatures taken on a worst case individual inputcircuit with neighboring input circuits loaded as well.102.4 F
20、or combiner units where the output rating is less than the sum of the input ratings (the mathematicproduct of the number of input circuits, multiplied by the units maximum input circuit rated current, exceedthe combiner units output rating), the unit shall be temperature tested in accordance with 10
21、2.4.1.102.4.1 When required by 102.4, and for combiner units rated for vertical mounting, the uppermost inputcircuit(s) located physically at the top of the combiner unit shall be adjusted independently to 100% ofRated input current. If the unit allows for multiple columns of OCPD input devices then
22、 all of the inputcircuits in the two uppermost rows located physically at the top of the unit shall be run at 100%.Successive input circuits below the top row shall be loaded to within 2% of the input rating for that circuitand such that the overall combiner unit test circuit is loaded to 100% of it
23、s output rating. At minimum, thetop two rows of combiner input circuit components shall be monitored for temperatures. If necessary toprevent overloading of the output circuit, an input circuit located physically at the bottom of the combinerunit is be loaded to a lower value to achieve the 100% out
24、put rating.102.4.2 When required by 102.4, and for combiner units rated for mounting orientations other thanvertical, the input circuits shall be loaded as noted in 102.4.1 and temperatures taken on a worst caseindividual input circuit with adjacent input circuits loaded as well.102.5 The test sampl
25、e shall be wired using the smallest gauge wire specified by the units instructions forthe maximum current rating of the combiner unit. If the installation instructions specify multiple currentratings, wire temperature ratings and wire size combinations, the measured component and wiretemperatures sh
26、all not exceed their ratings under the various combinations.103 Ratings103.1 A PV circuit combiner shall include the following ratings:Rated output current - (dc)Rated input current - (dc)Maximum Overcurrent Protection rating. The term “Overcurrent Protection” may be replaced with “Fuse”or “Circuit
27、Breaker”.Maximum system voltage (dc)Maximum Number of input circuitsMaximum Ambient (C)Enclosure Ratings104 Markings104.1 A PV input combiner unit shall be marked in accordance with the applicable portions of Section 63.Exception - The ratings in section 103 shall be marked on the product to replace
28、 the marking required inparagraph 63.2 c)104.2 Rated current for each input position should be marked on the unit (unless all inputs are identical).STANDARD NUMBER: UL 1741 -3-UL COPYRIGHTED MATERIAL NOT AUTHORIZED FOR FURTHER REPRODUCTION ORDISTRIBUTION WITHOUT PERMISSION FROM UL104.3 Units that co
29、mply with 101.5 may be marked, “Suitable for use in an Ungrounded or Non-isolatedArray,” or equivalent.105 Cautionary Markings105.1 A PV input combiner unit shall be marked in accordance with the applicable portions of Section 64.106 Equipment Information and Instructions106.1 A PV input combiner un
30、it shall include equipment information and instructions as defined in theapplicable portions of Section 65106.2 Installation instructions shall not specify or recommend ampacity rating for PV source circuit OCPDsor wiring that conflict with NEC 690.8 and shall not recommend exceeding the PV module m
31、arkedmaximum fuse / OCPD rating.107 Important Safety Instructions107.1 A PV input combiner unit shall include instructions in accordance with the applicable portions ofSection 66.RATIONALE FOR DECISION:The published UL 1741 standard does not include specific requirements for products that include or
32、perform PV input circuit combiner features and functions. PV combiner boxes may be significantly differentthan other t power distribution applications. These combiner units need to operate safely under severalcontinuous severe PV operating conditions including: operation during high irradiance condi
33、tions andoperation in rated ambient that are often above 40C. This document provides clarification on how to applyUL 1741 to these product types.This revision to the original CRD provides more clarification to the test method addresses some conflictingtext and corrects some errors.Copyright 2013 Und
34、erwriters Laboratories Inc.UL, in performing its functions in accordance with its objectives, does not guarantee or warrant thecorrectness of Certification Requirement Decisions it may issue or that they will be recognized or adoptedby anyone. Certification Requirement Decisions are the opinion of U
35、nderwriters Laboratories Inc. inpractically applying the requirements of the standard. They do not represent formal interpretations of thestandard under American National Standards Institute (ANSI) processes. UL shall not be responsible toanyone for the use of or reliance upon Certification Requirem
36、ent Decisions by anyone. UL shall not incurany obligation or liability for damages, including consequential damages, arising out of or in connectionwith the use or reliance upon Certification Requirement Decisions. The electronic version of theCertification Requirement Decision is the current version and previously printed copies may be outdated.This document is published as a service to ULs certification customersSTANDARD NUMBER: UL 1741 -4-
