Question - What is the simplest, least expensive, way to define an isolation transformer used in a UL508 (or similar standard) recognized product? The transformer is a custom design made by a magnetics vendor for use in our industrial products. The product is manufactured under a UL coordinated insulation system or recipe. Do I need the manufacture to obtain a UL construction file? I am concerned about managing our UL inspections since I can not prove the construction at our sight. What is the best way to handle the inspection issues? I run into this issue with some of our switch mode power supply isolation transformers. Typically these have a construction file. But I have been told that I don't always need to do this. I am confused!
Details - My latest application is a Current Transformer used in power distributions systems. A power main transformer steps down the supply current to 0-5 Amp and then the CT in my product steps this down again to mA range for measurement purposes. These CTs in my product become referenced safety barriers in the UL product file but do not normally have high voltages on the primary. My magnetics vendor says I do not need the construction file but I do not see how I can get a split inspection with UL inspecting the CT at the vendor, with out this. Is there another way? Guidance on this topic would be most appreciated. Thank you Chris Wells Senior Des Eng. [email protected] Cutler-Hammer 412 490 6862
