Design of a motor circuit as per standard ul 508 part iv and ul 508a chap. Ul 508a sb determining sccr three basic steps ul 508a supplement sb shortcircuit current ratings for industrial control panels shall be determined by the following evaluation procedure. Supplement sb, provides an analytical method to determine the short circuit current rating of an industrial control panel. Since 2006, manufacturers of custom control panels that have the ul listed. The process for ul 508a, supplement sb analyzes the sccr for power circuit components, determines if these ratings can be raised by currentlimiting devices in the feeder circuit, and compares the lowest component rating with the lowest interrupting rating of overcurrent devices to determine the assembly sccr. Jul 07, 2015 in 2005 ul 508a was changed to require control panel builders to include a short circuit current rating on the control panel assembly. Supplement sb, provides an analytical method to determine the shortcircuit current rating of an industrial control panel. Sccr rating marked on the component use assumed sccrs in table sb 4. The table below is extracted from the ul 508a supplement sb, table sb4. Determine the sccr of all individual power components by one of the following methods. Purchase ul standards online official ul standards sales.
Ul 508a, but is by no means an exhaustive guide, and does not cover all uses and applications associated with ul 508a regulations. Shortcircuit current rating application and codes training. The method stipulated in ul 508a, supplement sb, is also referenced in article 670, industrial machinery. Second, see if there are current limiting devices ahead of the control panel that will limit the actual amount of current available at the control panel during a short.
Article requires all industrial control panels to be marked with a short circuit current. Tested product combinations to meet nec article 409 and ul. The first half of the second day instructs existing industrial control panel customers on how to establish shortcircuit ratings for individual industrial control panels in accordance with the requirements outlined in the new standard for industrial control panels, ul 508a, 3rd edition, supplement sb. While that seems a reasonable request, and is certainly in the best interest of safety, in practice it can be difficult to comply with. Using currentlimiting fuses to increase short circuit. Underwriters laboratory implemented ul508a supplement sb to. Basic steps for calculating the sccr of a control panel. This document replaces what was supplement sa in the second edition of ul 508a, and subsequently appendix c in the third edition of ul 508a. The ul listing mark on an industrial control panel provides evidence of third party certification to the municipal inspection authority and to the purchaser of the panel.
Determining sccr for industrial control panels and. Supplement sb is the ul approved method for determining the sccr for industrial control panels based on the power circuit components within the. Control panel technical guide how to ensure troublefree approval of your ulcompliant control panels 8 2 ul standards and circuit design design of a motor circuit as per standard ul 508 part iv and ul 508a chap. This method is based upon the weakest link approach. Ul 508a online certifications directory outline of ul 508a slide 3 industrial control procedure ul508a descriptive procedure part 1 general use supplement sa specific component requirements part 2 specific use information you provide specific components not. Ansiul 508a, standard for industrial control panels, supplement sb, is an example of an approved method. Short circuit current ratings calculation and tools. Ul 508a, the standard for safety for industrial control panels is referenced overall in the article for evaluating control panels and its supplement sb is noted as being an approved method for establishing the short circuit current rating of the panel. For each, protection and control functions are stipulated. Reference manual shortcircuit current rating sccr of. Shortcircuit current rating markings are not required for industrial control panels containing only control circuit components. Ul 508a supplement sb is given as an example of an approved method. This document gives guidelines to panel builders on various issues including proper component selection, wiring. In the case of a motor feeder, a number of component combinations may be used to ensure the functions, however.
Evaluate panel per ul508a, supplement b required by 406 if jurisdiction does not adopt 2005 nec earlier. Nec article 409 and ul 508a shortcircuit current rating sccr of industrial control panels. Ul 508a supplement sb requires a 3step process to determine the sccr of an industrial control panel. This guide is not intended to be used in lieu of ul 508a or other regulatory standards. Requirements for industrial control panel safety, conductors. Supplement sb is the ul approved method for determining the sccr for industrial. Equipment sccr, industrial control panel devices and ul 508a supplement sb. Littelfuse using currentlimiting fuses to increase sccr pdf. This supplement is the only method specifically noted as being. Underwriters laboratory implemented ul508a supplement sb. Purcell systems manufactures ul 508a certified enclosures and cabinets to the ul 508a safety standard this manual contains notices you have to observe in order to ensure your personal safety, as well as to prevent damage to property. Ul 508a industrial control panels power distribution and. Utilize a method described by underwriters laboratories inc. How to determine shortcircuit current ratings iaei magazine.
The ul 508a supplement sb method does not require the panel to be listed. Requirements for industrial control panel safety, implications of ul. Underwriters laboratory implemented ul 508a supplement sb to. Ul 508a supplement sa specific component requirements. Shortcircuit current rating sccr a first, establish the short circuit current ratings of individual power circuit components as specified in sb4. Each copy is watermarked with the purchasers information. Control components branch and feeder circuits power transformer vs. The elevator control panel shall not be installed where the available shortcircuit current exceeds its shortcircuit current rating, as marked in accordance with 620. With the numerous possibilities for product combinations within a panel, this option will require a tremendous investment in testing and maintenance. Once you have all of the component ratings, either use an outside service or ul 508a supplement sb. Ul508a is a safety standard for industrial control panels adopted by underwriters. Equipment intended to be connected to a source of supply greater.
The nec proposes the method stipulated in ul 508a, supplement sb, as an example for shortan approved method. Identify the lowest component sccr andor component combination sccr rating with an overcurrent protective device ocpd. Ul 508a, supplement sb is an approved method to determine sccr for industrial control panels and industrial machinery control panels. This is typically somewhere between 240vac 600vac, 3 phase power. We design, assemble, and install ul certified panels and can bring existing control panels up to ul safety standards, as well as build panels from the ground up meeting the customer requirements, while following ul safety standards. Purchase previously tested combinations from a major supplier that can be tabulated in the panel builders procedure.
The process for ul 508a, supplement sb analyzes the sccr for power circuit components, determines if these ratings can be raised by currentlimiting devices in the feeder circuit, and compares the lowest component rating with the lowest interrupting rating of overcurrent devices. In 2005 ul 508a was changed to require control panel builders to include a short circuit current rating on the control panel assembly. Always consult all pertinent actual regulatory standards and local standard representatives to ensure full compliance. First, find out the lowest sccr of any component in the control panel. Ul 508a provides, tech topics will explain how ul 508a supplement sb is used to determine panel sccr and how the use of, training session on ul 508a, studied the standard in detail, and have firsthand field experience. A ul 508a certification is an industrial control panel directive, which electrical inspectors look for. Instruction sheets with sccr ratings ul tested combinations pdf. All components in power circuit must have ratings ratings of starters are typically based on hp rating supplement sb, table sb4. Ul 508a covers industrial control panels and industrial panel enclosures operating at 600 volts.
Latest facebook app for nokia s40 latest facebook app for n. Ul 508a supplement sb is the preferred option for nearly all industrial control panels. If your jurisdiction does not adopt the 2005 code, control panels certified to the ul 508a standard will require a sccr rating in april 2006. Ul 508a standard pdf download gaaphakerslingbeachs blog. Eaton is a major component supplier that is committed to providing this information to our customers. Join us for a 3hour training session on equipment shortcircuit current ratings sccrs and national electrical code nec requirements, understanding industrial control panels devices, and ul 508a supplement sb. Harmonization of iec and north american safety standards. Ul 508a industrial control panels power distribution and control. Once you have all of the component ratings, either use an outside service or ul508a supplement sb. Ul508a supplement sb4 is the approved method for determining short circuit. How to ensure troublefree approval of your ulcompliant. The power circuit supplies electricity to the workers that do the heavy lifting, powering large motors, for example. A brief history of ul 508a and tips for how control panel.
The second day instructs industrial control panel customers on how to establish shortcircuit ratings for individual industrial control panels in accordance with the requirements outlined in the new standard for industrial control panels, ul 508a, 3rd edition, supplement sb. Ul 508a20, supplement sb, is an example of an approved method. Requirements for industrial control panel safety, implications of ul 508a 2nd edition. Apr 06, 2018 equipment sccr, industrial control panel devices and ul 508a supplement sb. Schneider electric codes and standards 2017 nec changes. Ul 508a covers industrial control panels and industrial panel enclosures operating at 600. Ul 508a supplement sb ul508a is a safety standard for industrial control panels adopted by underwriters laboratory which is an approved method in determining sccr referenced by nec article 409. Overview of supplement sb from the ul 508a standard. Ansi ul 508a, standard for industrial control panels, supplement sb, is an example of an approved method.
At the municipal, county and state levels, electrical codes are being amended at an increasing rate to include the requirement for sccr labeling of industrial control panels per nec409. Ul now offers the ability to purchase a premium hard copy of any ul standard. Prior to the release of the latest edition of ul 508a, supplement sb dated december 20, 20, sccr applied only to the power circuit of a control panel. Ul508a is the ul standard for the construction of industrial control panels. Underwriters laboratory 508a overview of ul508a supplement sb ul 508a is a safety standard for industrial control panels adopted by underwriters laboratory, which is an approved method in determining sccr referenced by nec article 409. Nec article 409 references ul508a supplement sb as an approved method for determining. Ul 508a, supplement sb, provides an analytical method to determine the shortcircuit current rating of an industrial control panel.
Formerly supplement sa of ul 508a 1 listed components 1. Supplement sb describes how to assign the sccr to a panel based on the ratings of the individual power components and types of currentlimiting power devices used within the panel. Ul 508a online certifications directory outline of ul 508a slide 3 industrial control procedure ul508a descriptive procedure part 1 general use supplement sa. Test each panel construction and record the construction in a followup procedure. References in this document to sections or paragraphs in ul 508a are understood to be to the third edition of the standard with revisions dated july 3. It supersedes the previous version of this document. Please refer to the ul website to view the most uptodate table sb4. The ul 508a supplement sb method of assigning the sccr to an industrial control panel does not require the panel be listed. Ul 508a supplement sb ul 508a supplement sb describes three steps to determine the sccr of industrial control panels. Ul 508a, standard for industrial control panels, supplement sb, is an example of an approved method. Page ul enclosed sccr 1 air ul 508a ul 508a 1995 376. Ul 508a standard for industrial control panels standards.
307 288 612 1128 194 311 1183 456 820 945 966 8 299 497 554 266 1490 1110 1451 415 667 456 39 1100 361 688 1458 1371 127 1461 1377 47 696 600 1082