In load side power distribution industrial/commercial electrical sub-metering applications (feeder and branch circuits)we use IEC/EN/UL61010-1 3rd (plus 61010-2-030 for the current transformers (CT)) to evaluate our meter's safety design. In this application the instrument current transformer sensors typically sit on the power load cables of 120-347VL:N /208-600VL:L mains in panel boards and switch panels at the feeding breaker.
The CT goes over the power cable's insulating sheath but may be located near the point where the power cable is stripped and inserted into the breaker lug and so the value of the cable's sheath is not considered in this evaluation. The meter's input is the secondary of these CT circuits without any additional isolation; therefore the CT must provide all of the isolation. Safety design wise this ends up requiring "double/reinforced isolation for 600V and Over Voltage CAT III" (metering category CAT III) between the primary and secondary circuits of the CT. We have evaluated a group of CTs along with our submeter as a system however I would like to have some independence from this system approach with our CT vendors. In review with UL they said if we required the CTs to be validated to provide "double/reinforced isolation for 600V CATIII" then we should satisfy the requirements of our submeter. Many of the CT vendors in the USA use IEEE C57.13 to evaluate their CTs. This is not an European safety standard with the concept of isolation redundancy in it. Some of the designs may meet the physical requirements of providing "double/reinforced isolation for 600V CATIII" but need a standard to be reviewed/validated to. 61010 works for the submeter and the CTs as a system but what standard would be best to use to validate/control the CT production as a separate independent component? Chris Wells Eaton - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <emcp...@radiusnorth.net> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
