Information on UL (Underwriters Laboratories) Application areas for UL 508 and UL 508A UL 508 describes industrial control components and is For example, this standard contains information on: therefore the decisive standard for the assessment of Rittal Machine controllers SV components. Elevator controllers For example, this standard contains information on: Crane controllers Starters Equipment for heating, air-conditioning and ventilation Relays and contactors systems and describes, for example, in table SA 1.1 the Circuit-breakers devices which may be used in this standard and the Controllers requirements governing the standard and category number. UL 508A describes industrial control panels and is therefore the decisive standard for switchgear manufacturers. Both standards describe control systems for general indus- trial applications with a rated voltage of up to 600 V. The maximum permissible ambient temperature is 40 °C. Distinguishing between feeder and branch circuits Standard UL 508A makes a distinction between feeder cir- The term “branch & control circuits” refers to the part of the cuits and branch & control circuits. Generally speaking, the circuit located after the last overcurrent protective device. term “feeder circuits” refers to the part of the circuit located When using busbar systems, it is important to know whether at the supply end before the last overcurrent protective the application is in the feeder section or the branch sec- device (a device approved to UL 489). Increased require- tion, as the requirements governing the required creepage ments with regard to creepage distances and clearances distances and clearances are significantly higher for feeder apply to this part of the circuit. circuits. Important notes for the use of busbar systems to UL 508A 1. Creepage distances and clearances 2. Rated currents For untested busbar applications, UL 508A specifies a cur- One of the principal requirements in UL 508A is the amendment to the required creepage distances and rent carrying capacity of 1000 A/inch2 (1.5 A/mm2) in the absence of testing. This value may be higher if the product clearances for feeder circuits. The following distances are or application has undergone suitable testing. Rittal has con- required for applications >250 V: Between phases: ducted extensive testing in this respect in order to give users the maximum benefits when using the RiLine60 busbar sys- A Creepage distance 50.8 mm (2 inches) tem. The benefit of such testing is that SV busbar systems B Clearance 25.4 mm (1 inch) with higher rated currents may be used than permitted by Between phase and earthed, uninsulated metal parts: the default value. For example, a busbar with dimensions A Creepage distance 25.4 mm (1 inch) B Clearance 25.4 mm (1 inch) 30 x 10 mm can take 700 A instead of 465 A. Rittal RiLine60 complies with these requirements. 3. Terminals for factory or field wiring All busbar connection adaptors and component adaptors In accordance with the UL standards, connection terminals (OM adaptors with standard AWG connection cables may be approved for factory or field wiring. If a terminal is and circuit-breaker adaptors) have been designed in approved for factory wiring, it may only be used in switch- accordance with these requirements. However, users should gear assembly by suitably trained professionals. If connec- bear in mind a small number of differences from the IEC tion terminals are to be used in the field (e.g. on a construc- version: tion site), the component must be approved for field wiring. Special UL busbar supports for flat bars and Rittal PLS The terminals of the busbar connection adaptors and with increased creepage distances and clearances. component adaptors in the Rittal RiLine60 series have In order to guarantee the required distances between live therefore been tested for field wiring applications. parts and the earthed mounting plate, the use of a RiLine60 base tray is compulsory. Definition of creepage distances and clearances: D C A Creepage distance between active conductors/busbars B Clearance between active conductors/busbars C Creepage distance between active conductors/busbars A and earthed metal parts B D Clearance between active conductors/busbars and earthed metal parts Technical System Catalogue/Power distribution 2- 18
Technical System Catalogue RiLine60
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